JP6282763B2 - Decoding device, encoding device, decoding method, and encoding method - Google Patents

Description

  Embodiments described herein relate generally to a decoding device, an encoding device, a decoding method, and an encoding method.

  An image including a luminance component and a color difference component is encoded after converting the resolution of the color difference component. At the time of decoding, the resolution of the color difference component is converted after decoding the encoded data. The resolution of the color difference component includes a color difference format such as 4: 4: 4 format, 4: 2: 2 format, and 4: 2: 0 format.

  By repeating the conversion of the resolution of the color difference component, image quality degradation occurs. For this reason, attempts have been made to suppress degradation of image quality. Specifically, it is disclosed that a filter that satisfies the condition for suppressing image quality deterioration is designed as a filter used for converting the resolution of the color difference component.

JP 2005-123913 A JP 2009-246929 A

  Conventionally, however, image quality degradation may occur depending on the resolution of the color difference component during reproduction.

  The problem to be solved by the present invention is to provide a decoding device, an encoding device, a decoding method, and an encoding method capable of suppressing image quality deterioration.

  The decryption apparatus according to the embodiment includes a reception unit, a decryption unit, and a conversion unit. The receiving unit reproduces the encoded data and the first color difference format indicating the resolution of the color difference component of the encoded data, which is generated according to a predetermined syntax, and the decoded image obtained by decoding the encoded data. Transmission information including a second color difference format indicating the resolution of the color difference component to be used and filter specifying information for specifying a filter used when converting the color difference format of the decoded image is received. The decoding unit generates the decoded image by decoding the encoded data included in the transmission information. The conversion unit performs color difference format conversion on the decoded image using a filter indicated by the filter specifying information. The first color difference format indicates the resolution of the color difference component of 4: 2: 2 format or 4: 4: 4 format and the second color difference format indicates the resolution of the color difference component of 4: 2: 0 format, or 1 color difference format indicates the resolution of the color difference component of 4: 4: 4 format, and the second color difference format indicates the resolution of the color difference component of 4: 2: 0 format or 4: 2: 2 format, and the filter specifying information includes: The conversion unit includes a horizontal downsampling filter and a vertical downsampling filter among a plurality of predetermined filters based on the filter coefficient, the first color difference format, and the second color difference format. Select the filter containing at least one and select the selected filter There the decoded image to chrominance format conversion.

The figure which shows the functional structure of an encoding apparatus. The figure which shows the functional structure of a conversion part. The figure which shows the functional structure of an encoding part. The figure which shows the functional structure of a production | generation part. The figure which shows an example of the syntax of color difference conversion information. The figure which shows an example of the data structure of definition information. The figure which shows an example of the syntax of color difference conversion information. The figure which shows an example of the syntax of color difference conversion information. The figure which shows an example of the data structure of definition information. The figure which shows an example of the data structure of definition information. The figure which shows an example of the syntax which expresses color difference conversion filter information. The figure which shows an example of the syntax of color difference conversion information. The figure which shows an example of the syntax which expresses color difference conversion filter information. The figure which shows an example of the data structure of definition information. The figure which shows an example of the syntax which expresses color difference conversion filter information. The figure which shows an example of the data structure of definition information. The figure which shows an example of the syntax which expresses color difference conversion filter information. The flowchart which shows the procedure of an encoding process. The figure which shows the functional structure of an encoding apparatus. The figure which shows the functional structure of a production | generation part. The figure which shows the functional structure of a conversion part. The figure which shows the functional structure of a production | generation part. The figure which shows the functional structure of an encoding apparatus. The figure which shows the functional structure of a decoding apparatus. The figure which shows the functional structure of a decoding part. The figure which shows the functional structure of a decoding part. The figure which shows the functional structure of a conversion part. The flowchart which shows the procedure of a decoding process. The figure which shows the functional structure of a decoding part. The figure which shows the functional structure of a conversion part. The figure which shows the hardware constitutions of an encoding apparatus and a decoding apparatus.

(Embodiment 1)
FIG. 1 is a schematic diagram illustrating a functional configuration of the encoding apparatus 10 according to the present embodiment.

  The encoding device 10 performs encoding after changing the resolution of the color difference component of the original image. The original image is an image including a luminance component and a color difference component. The resolution of the color difference component includes a color difference format such as 4: 4: 4 format, 4: 2: 2 format, and 4: 2: 0 format. In the present embodiment, an original image in any one of these color difference formats is input to the encoding device 10.

  In the present embodiment, as an example, a case where an original image in a color difference format of 4: 4: 4 format is input to the encoding device 10 is described, but the present invention is not limited to this mode.

  The encoding device 10 includes a conversion unit 12, an encoding unit 14, a generation unit 16, a NAL unit generation unit 18, and a transmission information generation unit 20.

  The conversion unit 12 converts the resolution of the color difference component of the original image by filtering the original image. The converter 12 outputs the original image obtained by converting the resolution of the color difference component as a color difference converted image. In the present embodiment, the conversion unit 12 will describe a case where the resolution of the color difference component is enlarged (upsampling) for the original image.

  FIG. 2 is a schematic diagram illustrating a functional configuration of the conversion unit 12.

  The conversion unit 12 includes one or more conversion units that convert the resolution of the color difference component for the original image input to the encoding device 10. Note that the conversion of the resolution of the color difference component by the conversion unit 12 may be referred to as color difference format conversion. In the present embodiment, the conversion unit 12 includes a conversion unit 12A, a conversion unit 12B, and an output adjustment unit 12C.

  The conversion unit 12A converts the 4: 4: 4 format original image into a 4: 2: 2 format image. Specifically, the conversion unit 12A performs a filtering process using a filter that thins out the chrominance components of the pixels constituting the original image of the 4: 4: 4 format by 1/2 in the horizontal direction. As a result, the conversion unit 12A performs downsampling by thinning the color difference components of the pixels constituting the 4: 4: 4 format original image by 1/2 in the horizontal direction, and converts the image to a 4: 2: 2 format image. . The converter 12A outputs the 4: 2: 2 format image to the converter 12B.

  The conversion unit 12B receives an image in 4: 2: 2 format from the conversion unit 12A. The conversion unit 12B converts the received 4: 2: 2 format image into a 4: 2: 0 format image. More specifically, the conversion unit 12B performs a filtering process using a filter that thins out the chrominance components of the pixels constituting the 4: 2: 2 format image by 1/2 in the vertical direction. As a result, the conversion unit 12B performs downsampling by thinning out the color difference components of the pixels constituting the 4: 2: 2 format image by 1/2 in the vertical direction, and converts the image to a 4: 2: 0 format image. The converter 12B outputs an image in 4: 2: 0 format to the output adjuster 12C.

  The output adjustment unit 12C has a range in which each pixel value constituting the 4: 2: 0 format image received from the conversion unit 12B is not less than the minimum value specified in the standard and not more than the maximum value specified in the standard. Clipping processing is performed so that Then, the image after clipping processing is output to the encoding unit 14 as a color difference converted image obtained by performing color difference conversion by the conversion unit 12. The color difference converted image is an original image after the resolution of the color difference component is converted by the conversion unit 12.

  Returning to FIG. 1, the conversion unit 12 outputs the color difference converted image to the encoding unit 14. Further, the conversion unit 12 outputs the color difference signal information to the generation unit 16.

  The color difference signal information includes filter information used in the filtering process by the conversion unit 12. In the present embodiment, the color difference signal information is the 4: 4: 4 format original image received by the conversion unit 12A, the filter information used for the filter processing by the conversion unit 12A, and the 4: 2 received by the conversion unit 12B. : 2 format image and filter information used for filter processing in the conversion unit 12B.

  Note that the filter information used for the filter processing in the conversion unit 12A is horizontal downsampling filter information in the present embodiment. In addition, the filter information used for the filter processing in the conversion unit 12B is vertical downsampling filter information in the present embodiment.

  The encoding unit 14 receives a color difference converted image from the conversion unit 12. The encoding unit 14 encodes the received color difference conversion image and generates encoded data. In the present embodiment, the encoding unit 14 divides one frame into slices composed of a plurality of pixel regions and performs encoding for each slice.

  FIG. 3 is a schematic diagram illustrating a functional configuration of the encoding unit 14.

  The encoding unit 14 includes a subtraction unit 14A, a transform / quantization unit 14B, an entropy encoding unit 14C, an inverse quantization / inverse transform unit 14D, an addition unit 14E, a frame memory 14F, a predicted image generation unit 14G, and a motion vector search. 14H is provided.

  The subtractor 14 </ b> A receives the color difference converted image from the converter 12. The subtracting unit 14A obtains a difference between the color difference converted image and the predicted image generated by the predicted image generating unit 14G, and generates an error image that is the difference.

  The transform / quantization unit 14B transforms the error image to generate transform coefficients, and quantizes the transform coefficients to generate quantized coefficients. Examples of the error image conversion method include orthogonal transform using DCT (Discrete Cosine Transform), wavelet transform, independent component analysis, and the like. The transform / quantization unit 14B transforms the error image using any one of these transform methods. Further, the transform / quantization unit 14B quantizes the transform coefficient using a preset quantization parameter.

  The transform / quantization unit 14B outputs the quantization coefficient to the entropy coding unit 14C and the inverse quantization / inverse transform unit 14D.

  The entropy encoding unit 14C receives the quantization coefficient from the transform / quantization unit 14B. The entropy encoding unit 14C receives motion vector information from a motion vector search unit 14H described later. The entropy encoding unit 14C entropy encodes the quantization coefficient and the motion vector information according to a predetermined syntax to generate encoded data. The syntax is a rule for setting encoded data.

  The entropy encoding unit 14C performs entropy encoding using, for example, Huffman encoding or arithmetic encoding.

  The entropy encoding unit 14C outputs the generated encoded data to the NAL unit generation unit 18.

  The inverse quantization / inverse transform unit 14D performs inverse transform after dequantizing the quantization coefficient, and generates an error image. That is, the inverse quantization / inverse transform unit 14D performs a process opposite to the process of the transform / quantization unit 14B on the quantization coefficient. Specifically, when the transform / quantization unit 14B performs wavelet transform and quantization, the inverse quantization / inverse transform unit 14D performs inverse quantization and inverse wavelet transform.

  The adding unit 14E receives an error image from the inverse quantization / inverse transform unit 14D and receives a predicted image from the predicted image generation unit 14G. Then, the adding unit 14E adds the error image and the predicted image to generate a decoded image. This decoded image is stored in the frame memory 14F.

  The frame memory 14F performs filtering on the decoded image and stores it as a reference image. The frame memory 14F outputs the reference image to the predicted image generation unit 14G and the motion vector search unit 14H.

  The motion vector search unit 14H generates motion vector information using the color difference converted image received from the conversion unit 12 and the reference image received from the frame memory 14F. The motion vector search unit 14H outputs the generated motion vector information to the predicted image generation unit 14G and the entropy encoding unit 14C.

  The predicted image generation unit 14G generates a predicted image using the reference image and motion vector information. Then, the predicted image generation unit 14G outputs the generated predicted image to the addition unit 14E and the subtraction unit 14A.

  Here, the reference image generated by the frame memory 14F is an image having the same color difference format as that of the color difference conversion image. That is, in the present embodiment, the reference image is the same 4: 2: 0 format image as the color difference converted image obtained by converting the resolution of the color difference component by the conversion unit 12. In the present embodiment, the frame memory 14F outputs the reference image in the 4: 2: 0 format to the generation unit 16.

  Returning to FIG. 1, the generation unit 16 receives color difference signal information from the conversion unit 12. Further, the generation unit 16 receives a reference image in the same color difference format (4: 2: 0 format) as that of the color difference conversion image from the encoding unit 14. The generation unit 16 generates color difference conversion information using the color difference signal information and the reference image of the color difference format of the color difference conversion image.

  The color difference conversion information includes a first color difference format and filter specific information used at the time of color difference format conversion of a decoded image obtained by decoding encoded data.

  In the present embodiment, as an example, a case will be described in which the color difference conversion format includes a first color difference format, a second color difference format, and specific information.

  The first color difference format indicates the resolution of the color difference component of the encoded data encoded by the encoding unit 14, that is, the color difference format. In other words, the first color difference format is the color difference format of the color difference converted image. In the present embodiment, the first color difference format is a 4: 2: 0 format. In the following description, the resolution of the color difference component may be simply referred to as a color difference format.

  The second color difference format is a color difference format at the time of reproduction of a decoded image obtained by decoding encoded data. “When playing back a decoded image” refers to a color difference format used when playing back a decoded image obtained by decoding encoded data, and is determined by the playback mode, playback equipment, and the like. In the present embodiment, the second color difference format is preset in the generation unit 16. The second color difference format may be received by the encoding device 10 together with the original image. The second color difference format may be received from an external device or the like via a communication unit (not shown).

  The identification information is information for identifying a filter used when converting the color difference format of the decoded image.

  In the present embodiment, as an example, a case will be described in which the specific information is information for specifying a filter used when converting a decoded image in the first color difference format into the second color difference format. In the present embodiment, a case will be described in which the specific information is filter information used for converting a decoded image in the first color difference format into the second color difference format. The filter information includes, for example, a filter coefficient.

  Note that the specific information may include reference information of the second color difference format. The reference information may be information such as a flag for specifying the second color difference format, or may be the second color difference format itself.

  FIG. 4 is a schematic diagram illustrating a functional configuration of the generation unit 16.

  The generation unit 16 receives color difference signal information from the conversion unit 12. Further, the generation unit 16 receives a reference image in the same color difference format (4: 2: 0 format) as that of the color difference conversion image from the encoding unit 14.

  As described above, in this embodiment, the color difference signal information includes the 4: 4: 4 format original image received by the conversion unit 12A, the filter information used for the filter processing by the conversion unit 12A, and the conversion unit 12B. The received 4: 2: 2 format image and the filter information used in the filtering process by the conversion unit 12B are included.

  The generation unit 16 includes a vertical filter information generation unit 16A, a conversion unit 16B, a horizontal filter information generation unit 16C, and a generation unit 16D.

  The vertical filter information generation unit 16A receives the 4: 2: 2 format image and the filter information (vertical downsampling filter information) used for the filter processing in the conversion unit 12B among the information included in the color difference signal information. Further, the vertical filter information generation unit 16A receives a reference image in the same color difference format (4: 2: 0 format) as the color difference conversion image from the encoding unit 14.

  The vertical filter information generation unit 16A is a 4: 2: 2 format image, vertical downsampling filter information used for filter processing by the conversion unit 12B, and a color difference format image converted by the conversion unit 12B. The filter information used to convert the 4: 2: 0 format image to the 4: 2: 2 format from the: 0 format reference image is designed.

  That is, the vertical filter information generation unit 16A designs filter information used to obtain an image in 4: 2: 2 format by performing vertical upsampling processing on a reference image in 4: 2: 0 format. . Then, the vertical filter information generation unit 16A outputs the vertical filter information that is the designed filter information to the conversion unit 16B and the generation unit 16D.

  In designing filter information, the following formulas (1) to (3) are used.

  Equations (1) to (3) are equations for calculating a filter that minimizes the root mean square of the difference between the color difference component of the image before filter processing and the color difference component of the image after filter processing, that is, a Wiener filter. .

In Formula (1), F shows a filter coefficient. In formula (1), (f _{1 to} f _n ) represents a filter coefficient. Note that n represents an integer of 1 or more.

In Expression (2), S represents the color difference component of the image after the filter processing. In formula (2), x represents the position of the pixel. In Formula (2) and Formula (3), S _F (x) represents the image signal after the filter processing. In formula (3), S _org represents the color difference component of the image before the filter processing.

  The conversion unit 16B receives a reference image in the same color difference format (4: 2: 0 format) as the color difference converted image from the encoding unit 14. Also, the conversion unit 16B receives vertical filter information from the vertical filter information generation unit 16A.

  The conversion unit 16B performs filter processing using the received vertical filter information, and converts the color difference format of the reference image in the same color difference format (4: 2: 0 format) as the color difference converted image into the 4: 2: 2 format. The conversion unit 16B outputs the 4: 2: 2 format image obtained by the conversion to the horizontal filter information generation unit 16C.

  The horizontal filter information generation unit 16C includes the 4: 4: 4 format original image received by the conversion unit 12A among the information included in the color difference signal information, and the filter information (horizontal downsampling used by the conversion unit 12A for filter processing). Filter information). In addition, the horizontal filter information generation unit 16C receives an image in 4: 2: 2 format from the conversion unit 16B.

  The horizontal filter information generation unit 16C converts the 4: 2: 2 format image from the 4: 4: 4 format original image, the horizontal downsampling filter information, and the 4: 2: 2 format image to 4: 4. : Design filter information used to convert to 4 format. For designing the filter information, the above formulas (1) to (3) are used.

  That is, the horizontal filter information generation unit 16C designs filter information used to obtain an original image in 4: 4: 4 format by performing horizontal upsampling processing on an image in 4: 2: 2 format. Then, the horizontal filter information generation unit 16C outputs the horizontal filter information that is the designed filter information to the generation unit 16D.

  The generation unit 16D generates color difference conversion information. Specifically, the generation unit 16D uses the color difference format (4: 2: 0 format) of the reference image received from the encoding unit 14 as the first color difference format of the encoded data encoded by the encoding unit 14. Further, the generation unit 16D reads the second color difference format at the time of reproduction of the decoded image obtained by decoding the encoded data from a memory (not shown). Further, the generation unit 16D uses the vertical filter information received from the vertical filter information generation unit 16A and the horizontal filter information received from the horizontal filter information generation unit 16C as the specific information. Then, the generation unit 16D generates color difference conversion information including the first color difference format, the second color difference format, and the specific information.

  The generation unit 16D generates color difference conversion information according to a predetermined setting rule (syntax).

  FIG. 5 is a diagram illustrating an example of syntax of color difference conversion information.

  Chrominance conversion information includes, as shown in FIG. 5, coded_format_idc, coded_data_bit_depth, target_format_idc, target_bit_depth, max_value, min_value, progressive_flag, implicit_vertical_flag, tap_length_vertical_minus1, ver_filter_coeff, implicit_horizontal_flag, interpolation_horizontal_idc, tap_length_horizontal_minus1, and Hor_filter_coeff.

  coded_format_idc indicates the first color difference format.

  For example, when the value of coded_format_idc is “0”, the first color difference format is a monochrome format in which only luminance is defined. When the value of coded_format_idc is “1”, the first color difference format is a 4: 2: 0 format. When the value of coded_format_idc is “2”, the first color difference format is a 4: 2: 2 format. When the value of coded_format_idc is “3”, the first color difference format is a 4: 4: 4 format.

  coded_data_bit_depth indicates the pixel bit length of the encoded data.

  target_format_idc indicates a second color difference format that is a color difference format at the time of reproduction of a decoded image obtained by decoding the encoded data. target_bit_depth indicates the pixel bit length during reproduction. max_value indicates the maximum value of the color difference component during reproduction. min_value indicates the minimum value of the color difference component during reproduction.

  progressive_flag is a flag indicating whether or not the encoded data is a progressive signal. For example, when the value of progressive_flag is “0”, the encoded data is not a progressive signal but an interlace signal. In this case, it indicates that the color difference conversion process needs to be performed in units of fields.

  implicate_vertical_flag, interpolation_vertical_idc, tap_length_vertical_minus1, ver_filter_coeff, implicate_horizontal_flag, interpolation_horizontal

  The implicit_vertical_flag is a flag indicating that vertical filter information defined in advance is used. interpolation_vertical_idc is identification information of filter information in the vertical direction defined in advance. tap_length_vertical_minus1 indicates the value of the tap length minus 1 of the filter coefficient in the vertical direction.

  ver_filter_coeff represents a filter coefficient in the horizontal direction. "implicit_horizontal_flag" is a flag indicating that predetermined horizontal filter information is used. Interpolation_horizontal_idc is identification information of the predefined filter information in the horizontal direction. tap_length_horizontal_minus1 indicates the value of the tap length minus 1 of the filter coefficient in the horizontal direction. hor_filter_coeff indicates a filter coefficient in the horizontal direction.

  For example, it is assumed that the value of coded_format_idc is “1”, that is, the first color difference format that is the format of the encoded data is the 4: 2: 0 format. Further, it is assumed that the value of target_format_idc is “1” or more, that is, the second color difference format that is the color difference format at the time of reproduction of the decoded image is 4: 2: 2 or 4: 4: 4 format. In this case, upsampling processing is required in the vertical direction. Therefore, in this case, the generation unit 16 generates vertical filter information (vertical upsampling filter information) as specific information.

  Further, it is assumed that the value of coded_format_idc is larger than “1”, that is, the first color difference format which is the format of the encoded data is the 4: 2: 2 format or the 4: 4: 4 format. Further, it is assumed that the value of target_format_idc is “1”, that is, the second color difference format that is the color difference format at the time of reproduction is the 4: 2: 0 format. In this case, the specific information is vertical filter information (vertical downsampling filter information).

  Further, it is assumed that the value of coded_format_idc is “1” or “2”, that is, the first color difference format is 4: 2: 0 format or 4: 2: 2 format. Further, it is assumed that the value of target_format_idc is “3”, that is, the second color difference format is a 4: 4: 4 format. In this case, the specific information is horizontal filter information (horizontal upsampling filter information).

  Further, it is assumed that the value of coded_format_idc is “3”, that is, the first color difference format is a 4: 4: 4 format. Further, it is assumed that the value of target_format_idc is “1” or “2”, that is, the second color difference format is 4: 2: 0 format or 4: 2: 2 format. In this case, the specific information is horizontal filter information (horizontal downsampling filter information).

  In FIG. 5, u (n) represents an n-bit non-negative binary expression. n is an integer of 1 or more. se (v) represents a signed 0th-order Exp-Golomb code.

  Note that the encoding device 10 generates a definition table that associates predefined vertical filter information and predefined horizontal filter information with identification information for identifying the filter information in advance. 16 is stored in a memory not shown.

  FIG. 6 is a schematic diagram illustrating an example of the data structure of the definition information.

  The definition information is a table in which Value, Tap length, and Filter coefficients are associated with each other.

  Value is identification information of filter information. Value corresponds to a value indicated by interpolation_vertical_idc or interpolation_horizontal_idc included in the color difference conversion information shown in FIG.

  Tap length indicates the tap length of the filter coefficient corresponding to the value of Value that is identification information of the filter information. Filter coefficient is a filter coefficient corresponding to the value of Value that is identification information of the filter information.

  The color difference conversion information may be in a form that does not include information obtained from the encoded data or standardized reproduction information.

  FIG. 7 is a diagram illustrating an example of syntax of color difference conversion information when information obtained from encoded data and standardized reproduction information is not included.

  Specifically, the color difference conversion information includes target_format_idc, progressive_flag, implicit_vertical_flag, tap_length_vertical_minus1, ver_filter_coeff, implicit_horizontal_flag, interpolation_horizontal_idc, tap_length_horizontal_minus1, and Hor_filter_coeff.

  That is, in the example shown in FIG. 7, the color difference conversion information does not include the first color difference format that is the color difference format of the encoded data and the pixel bit length. In the example shown in FIG. 7, the color difference conversion information does not include the pixel bit length at the time of reproduction and the maximum value and the minimum value of the color difference component at the time of reproduction.

  Note that, as described above, the color difference conversion information includes the first color difference format indicating the resolution of the color difference component of the encoded data and the filter specific information used when converting the color difference format of the decoded image obtained by decoding the encoded data. Any information may be used.

  FIG. 8 is a schematic diagram illustrating an example of syntax of color difference conversion information. FIG. 8 shows the case where the color difference conversion information includes the first color difference format, the pixel sample position of the color difference component of the encoded data, and the specific information.

  8, the color difference conversion information includes chroma_loc_info_present_flag, chroma_sample_loc_type_top_field, chroma_sample_loc_type_bottom_field_schem,

  chroma_loc_info_present_flag is a flag indicating whether or not there is a pixel position of the color difference signal and whether or not filter information relating to color difference conversion exists. For example, when the value of chroma_loc_info_present_flag is “1”, this flag indicates that there is filter information relating to the pixel position of the color difference signal and color difference conversion. Further, when the value of chroma_loc_info_present_flag is “0”, this flag indicates that there is no filter information regarding the pixel position of the color difference signal and color difference conversion.

  chroma_sample_loc_type_top_field indicates the pixel sample position (pixel position to be sampled) of the color difference component of the top field when the encoded data is encoded data encoded using interlace scanning. There are a total of six known combinations of pixel sample positions of the color difference component of the top field, in combination with the pixel sample position of the luminance component.

  chroma_sample_loc_type_bottom_field indicates the pixel sample position (pixel position of the sampling target) of the color difference component in the bottom field when the encoded data is encoded data encoded using interlace scanning. As in the case of the top field, there are a total of six known combinations of pixel sample positions for the color difference component in the bottom field depending on combinations with the pixel sample positions for the luminance component.

  chroma_filter_info_present_flag is a flag indicating whether or not filter information relating to color difference conversion exists. When the value of chroma_filter_info_present_flag is “1”, it indicates that there is filter information related to color difference conversion. When the value of chroma_filter_info_present_flag is “0”, it indicates that there is no filter information regarding color difference conversion.

  chroma_filter_info is identification information of the color difference conversion filter information. The color difference conversion filter information corresponding to the identification information of the color difference conversion filter information is preset in the color difference conversion filter definition information.

  FIG. 9 is a schematic diagram illustrating an example of the data structure of the color difference conversion filter definition information. The color difference conversion filter definition information is a table in which identification information of the color difference conversion filter information (corresponding to “Value” in FIG. 9) is associated with the color difference conversion filter information specified by the identification information.

  In the example illustrated in FIG. 9, the color difference conversion filter information includes Tap length, Filter coefficient, Divider, Phase shift, and Purpose.

  Tap length indicates the tap length of the filter coefficient. Filter coefficient is a filter coefficient. Divistor indicates the number of denominators when division is performed in the filter processing. Phase shift indicates the phase information of the filter. “Purpose” indicates the type of filter. Specifically, “Purpose” indicates a downsampling filter or an upsampling filter in the case of color difference format conversion.

  FIG. 10 is a schematic diagram illustrating another example of the data structure of the color difference conversion filter definition information. Similar to FIG. 9, the color difference conversion filter definition information shown in FIG. 10 includes color difference conversion filter information identification information (corresponding to “Value” in FIG. 10), color difference conversion filter information specified by the identification information, Is a table in which

  Also in the example illustrated in FIG. 10, the color difference conversion filter information includes Tap length, Filter coefficient, Divider, Phase shift, and Purpose as in FIG. 9.

  The color difference conversion filter definition information shown in FIG. 10 indicates that the color difference conversion filter information is generated according to a predetermined syntax when the value of “Value” as identification information is a specific value.

  FIG. 11 is a diagram illustrating an example of the syntax of the color difference conversion filter information. For example, when the value of “Value” that is identification information in the color difference conversion filter definition information shown in FIG. 10 is “1”, the color difference conversion filter information of the syntax shown in FIG. 11 is associated in advance.

  In this case, when the value of “Value” that is identification information in the color difference conversion filter definition information is “1”, the generation unit 16 generates the color difference conversion filter information according to the color difference conversion filter information of the syntax illustrated in FIG. .

  The color difference conversion filter information illustrated in FIG. 11 includes target_format_idc, num_of_filter_minus1, tap_length_minus1, and filter_coeff.

  target_format_idc is the same as described above. num_of_filter_minus1 indicates the value of the number of color difference conversion filters minus one. tap_length_minus1 indicates the value of the tap length minus 1 of the filter coefficient. filter_coeff indicates a filter coefficient.

  FIG. 12 is a schematic diagram illustrating another example of the syntax of the color difference conversion information. Note that FIG. 12 is different from the color difference conversion information shown in FIG. 8 in that chroma_filter_info is not included.

  In the example illustrated in FIG. 12, the color difference conversion information includes chroma_loc_info_present_flag, chroma_sample_loc_type_top_field, chroma_sample_loc_type_bottom_field_chroma_filter_scheme_filter_flag.

  chroma_filter_info_present_flag is a flag indicating whether or not filter information related to color difference conversion exists separately. When the value of chroma_filter_info_present_flag is “1”, it indicates that there is filter information related to color difference conversion. When the value of chroma_filter_info_present_flag is “0”, it indicates that there is no filter information regarding color difference conversion.

  FIG. 13 is a diagram illustrating an example of color difference conversion filter information that exists when the value of chroma_filter_info_present_flag in the color difference conversion information illustrated in FIG. 12 is “1”.

  13 includes num_of_filter_set_minus1, implicate_filter_set_flag, filter_set_idc, num_of_filter_minus1, _implicit_filter_flag, fil_us, thi_, fil_idc

  num_of_filter_set_minus1 indicates the number of filter sets minus one. The implicit_filter_set_flag is a flag indicating that information of a predetermined filter set is used. filter_set_idc is identification information of filter set information defined in advance. num_of_filter_minus1 indicates the value of the number of color difference conversion filters minus one. The implicit_filter_flag is a flag indicating that predetermined filter information is used. filter_idc is filter information identification information defined in advance. tap_length_minus1 indicates the value of the tap length minus 1 of the filter coefficient. filter_coeff indicates a filter coefficient.

  FIG. 14 is a schematic diagram illustrating an example of the data structure of the color difference conversion filter definition information, and is a diagram illustrating an example different from FIG. In the example illustrated in FIG. 14, the color difference conversion filter definition information is a table in which filter_set_idc, filter_idc, Tap length, Filter coefficients, Divider, Phase shift, and Purpose are associated with each other.

  filter_set_idc is identification information of filter set information. The value of the filter_set_idc corresponds to the filter_set_idc shown in FIG.

  filter_idc is identification information of filter information. The value of this filter_idc corresponds to the filter_idc shown in FIG.

  Tap length indicates the tap length of the filter coefficient as described above. Filter coefficient is a filter coefficient. Divistor indicates the number of denominators when division is performed in the filter processing. Phase shift indicates the phase information of the filter. “Purpose” indicates the purpose of the filter, and indicates downsampling and upsampling when converting the color difference format.

  FIG. 15 shows an example of color difference conversion filter information that exists when the value of chroma_filter_info_present_flag in the color difference conversion filter definition information is “1”.

  Chrominance conversion filter information shown in FIG. 15 includes target_format_idc, implicit_vertical_flag, vertical_filter_idc, tap_length_vertical_minus1, ver_filter_coeff, second_filter_flag, second_vertical_filter_idc, tap_length_second_vertical_minus1, second_ver_filter_coeff, implicit_horizontal_flag, horizontal_filter_idc, tap_length_horizontal_minus1, and Hor_filter_coeff.

  target_format_idc indicates the second color difference format, as in FIG. In the color difference conversion filter information shown in FIG. 15, the meaning for the value of target_format_idc is different from that in FIG. 5. Specifically, in the example illustrated in FIG. 15, when the value of target_format_idc is “0”, it indicates that the second color difference format is a monochrome format in which only luminance is defined. Further, when the value of target_format_idc is “1”, it indicates that the second color difference format is 4: 2: 0 format. Further, when the value of target_format_idc is “2”, it indicates that the second color difference format is 4: 2: 2 format. When the value of target_format_idc is “3”, it indicates that the second color difference format is a 4: 4: 4 format.

  Note that chroma_format_idc is included in the encoded data and indicates the first color difference format.

  The implicit_vertical_flag is a flag indicating that vertical filter information defined in advance is used. vertical_filter_idc is identification information of filter information in the vertical direction defined in advance. tap_length_vertical_minus1 indicates the value of the tap length minus 1 of the filter coefficient in the vertical direction.

  ver_filter_coeff indicates a filter coefficient in the vertical direction. Second_filter_flag is a flag defined when different filter sets are used in the vertical direction in the top field and bottom field in the case of a field signal. If the value of second_filter_flag is “1”, the second vertical filter is used. Filters can be defined.

  The second_vertical_filter_idc is identification information of second predefined filter information in the vertical direction. tap_length_second_vertical_minus1 indicates the value of the tap length minus 1 of the second vertical filter coefficient. second_ver_filter_coeff indicates a second vertical filter coefficient.

  "implicit_horizontal_flag" is a flag indicating that predetermined horizontal filter information is used.

  Horizontal_filter_idc is identification information of filter information in the horizontal direction defined in advance. tap_length_horizontal_minus1 indicates the value of the tap length minus 1 of the filter coefficient in the horizontal direction. hor_filter_coeff indicates a filter coefficient in the horizontal direction.

  For example, it is assumed that the value of chroma_format_idc is “1”, that is, the first color difference format that is the format of the encoded data is the 4: 2: 0 format. Further, it is assumed that the value of target_format_idc is “1” or more, that is, the second color difference format that is the color difference format at the time of reproduction of the decoded image is 4: 2: 2 or 4: 4: 4 format. In this case, upsampling processing is required in the vertical direction. Therefore, in this case, the generation unit 16 generates vertical filter information (vertical upsampling filter information) as specific information.

  Further, it is assumed that the value of chroma_format_idc is greater than “1”, that is, the first color difference format that is the format of the encoded data is the 4: 2: 2 format or the 4: 4: 4 format. Further, it is assumed that the value of target_format_idc is “1”, that is, the second color difference format that is the color difference format at the time of reproduction is the 4: 2: 0 format. In this case, the specific information is vertical filter information (vertical downsampling filter information).

  Further, it is assumed that the value of chroma_format_idc is “1” or “2”, that is, the first color difference format is 4: 2: 0 format or 4: 2: 2 format. Further, it is assumed that the value of target_format_idc is “3”, that is, the second color difference format is a 4: 4: 4 format. In this case, the specific information is horizontal filter information (horizontal upsampling filter information).

  Further, it is assumed that the value of chroma_format_idc is “3”, that is, the first color difference format is a 4: 4: 4 format. Further, it is assumed that the value of target_format_idc is “1” or “2”, that is, the second color difference format is 4: 2: 0 format or 4: 2: 2 format. In this case, the specific information is horizontal filter information (horizontal downsampling filter information).

  FIG. 16 is a schematic diagram showing an example of the data structure of the color difference conversion filter definition information different from FIG.

  The color difference conversion filter definition information illustrated in FIG. 16 is a table in which filter_idc, Tap length, Filter coefficients, Divider, Phase shift, and Purpose are associated with each other.

  In FIG. 16, filter_idc is identification information of filter set information. This corresponds to vertical_filter_idc, second_filter_idc, and horizontal_filter_idc included in the color difference conversion information shown in FIG.

  Tap length indicates the tap length of the filter coefficient. Filter coefficient is a filter coefficient. Divistor indicates the number of denominators when division is performed in the filter processing. Phase shift indicates the phase information of the filter. “Purpose” indicates the purpose of the filter, and indicates downsampling and upsampling when converting the color difference format.

  FIG. 17 shows an example of color difference conversion filter information that exists when the value of chroma_filter_info_present_flag in the color difference conversion information shown in FIG. 8 and FIG. 12 is “1”.

  17 includes target_format_idc, tap_length_vertical_minus1, ver_filter_coeff, second_filter_flag, tap_length_second_vertical_minus1, second_vert_vert, and second_vert_vert. Note that the difference between the color difference conversion filter shown in FIG. 17 and the color difference conversion filter shown in FIG. 15 is that all filter information is explicitly defined.

  Returning to FIG. 1, the generation unit 16 outputs the generated color difference conversion information to the NAL unit generation unit 18.

  The NAL unit generation unit 18 receives encoded data from the encoding unit 14. Further, the NAL unit generator 18 receives color difference conversion information from the generator 16.

  The NAL unit generation unit 18 includes NAL (Network) including the encoded data received from the encoding unit 14, the color difference conversion information received from the generation unit 16, header information, byte alignment information that is adjustment information at the time of writing and reading, and the like. Abstraction Layer) unit information is generated. The NAL unit generation unit 18 outputs the generated NAL unit information to the transmission information generation unit 20.

  The NAL unit information is information corresponding to high-level syntax included in transmission information to be described later output from the encoding device 10. The high-level syntax is higher-order syntax than the slice in the transmission information structure (syntax), and includes parameters that affect the entire transmission information frame. In the present embodiment, as described above, the NAL unit information includes encoded data, color difference conversion information received from the generation unit 16, header information, byte alignment information that is adjustment information at the time of writing and reading, and the like.

  The transmission information generation unit 20 receives NAL unit information from the NAL unit generation unit 18. The transmission information generation unit 20 converts the received NAL unit information into system layer information such as an MPEG-2 system or an ISO file format, and generates transmission information. The transmission information generation unit 20 outputs the generated transmission information.

  Next, an encoding process executed by the encoding device 10 will be described.

  FIG. 18 is a flowchart illustrating the procedure of the encoding process executed by the encoding device 10.

  First, the conversion unit 12 performs a color difference conversion process for converting the resolution of the color difference component for the original image received by the encoding device 10 (step S100). Then, the conversion unit 12 outputs the original image obtained by converting the resolution of the color difference component to the encoding unit 14 as a color difference converted image. Further, the conversion unit 12 outputs the color difference signal information to the generation unit 16.

  Next, the encoding unit 14 encodes the color difference conversion image received from the conversion unit 12 and generates encoded data (step S102). The encoding unit 14 outputs the encoded data to the NAL unit generation unit 18. In addition, the encoding unit 14 outputs a reference image having the same color difference format (4: 2: 0 format) as that of the color difference converted image to the generation unit 16.

  Next, the generation unit 16 generates color difference conversion information using the color difference signal information received from the conversion unit 12 and the reference image of the color difference format of the color difference conversion image received from the encoding unit 14 (Step S1). S104). The generation unit 16 outputs the generated color difference conversion information to the NAL unit generation unit 18.

  Next, the NAL unit generation unit 18 includes encoded data received from the encoding unit 14, color difference conversion information received from the generation unit 16, header information, byte alignment information that is adjustment information at the time of writing and reading, and the like. NAL unit information is generated (step S106). The NAL unit generation unit 18 outputs the generated NAL unit information to the transmission information generation unit 20.

  Next, the transmission information generation unit 20 converts the NAL unit information received from the NAL unit generation unit 18 into system layer information, and generates transmission information (step S108). The transmission information generation unit 20 outputs the generated transmission information.

  As described above, according to the encoding device 10 of the present embodiment, the encoding unit 14 encodes the color difference conversion image to generate encoded data. The generation unit 16 includes a first color difference format indicating the resolution of the color difference component of the encoded data, a second color difference format indicating the resolution of the color difference component when the decoded image obtained by decoding the encoded data is reproduced, and the first color difference format. Color difference conversion information including specific information for specifying a filter used when converting the decoded image of the encoded data into the second color difference format is generated.

  For this reason, when reproducing the decoded image obtained by decoding the encoded data encoded by the encoding device 10, the filter specified by the specific information included in the color difference conversion information is used to encode the encoded data of the first color difference format. By converting the decoded image into the second color difference format, it is possible to suppress image quality deterioration due to resolution conversion.

  Therefore, the encoding apparatus 10 according to the present embodiment can suppress image quality deterioration.

(Modification 1)
In the above embodiment, a case has been described in which the specific information is filter information used for converting the decoded image in the first color difference format into the second color difference format.

  However, the identification information may be information for identifying a filter used when converting the decoded image of the first color difference format to the second color difference format. For example, the specific information may be identification information for identifying filter information used for converting a decoded image in the first color difference format into the second color difference format.

  In this case, the definition information associating the filter information with the identification information of the filter information is stored in advance in the encoding device 10 and a decoding device (such as a decoding device described later) that decodes the encoded data. That's fine. On the device side that decodes the encoded data, the decoded image obtained by decoding the encoded data is subjected to filter processing using the filter information corresponding to the identification information included in the specific information, thereby changing the color difference format of the decoded image. Convert it.

  Further, the specific information may be filter information used in the filtering process by the conversion unit 12.

  In this case, the decoding device that decodes the encoded data sets a filter used when converting the decoded image in the first color difference format into the second color difference format from the filter information included in the specific information. And the decoding apparatus should just convert the color difference format of a decoded image using the set filter.

(Embodiment 2)
In the present embodiment, a mode in which color difference conversion information is generated by a method different from that in the first embodiment will be described.

  FIG. 19 is a schematic diagram illustrating a functional configuration of the encoding device 10A according to the present embodiment.

  The encoding device 10A includes a conversion unit 120, an encoding unit 14, a generation unit 160, a NAL unit generation unit 18, and a transmission information generation unit 20.

  10 A of encoding apparatuses are the structures similar to the encoding apparatus 10 of Embodiment 1 except having replaced with the conversion part 120 and having provided the conversion part 120 and the production | generation part 160 instead of the production | generation part 16. FIG.

  The conversion unit 120 has the same configuration as the conversion unit 12 except that the filter information used in the conversion unit 120 is output to the generation unit 160 as color difference signal information. Specifically, the conversion unit 120 outputs color difference signal information including the filter information used for the filter processing by the conversion unit 12A and the filter information used for the filter processing by the conversion unit 12B to the generation unit 160. In the present embodiment, as in the first embodiment, the filter information used in the conversion unit 12A is horizontal downsampling filter information, and the filter information used in the conversion unit 12B is vertical downsampling filter information. is there.

  The generation unit 160 receives color difference signal information from the conversion unit 120. The generation unit 160 generates color difference conversion information using the color difference signal information.

  FIG. 20 is a schematic diagram illustrating a functional configuration of the generation unit 160.

  The generation unit 160 includes a vertical filter information generation unit 160A, a horizontal filter information generation unit 160B, and a generation unit 160C.

  The vertical filter information generation unit 160A receives the filter information (vertical downsampling filter information) used for the filter processing by the conversion unit 12B among the information included in the color difference signal information.

  The vertical filter information generation unit 160A designs filter information used for converting an image in 4: 2: 0 format into 4: 2: 2 format from the vertical downsampling filter information used in the conversion unit 12B. That is, the vertical filter information generation unit 160A designs filter information used to obtain a 4: 2: 2 format image by performing a vertical upsampling process on a 4: 2: 0 format decoded image. . The design of the filter information is performed using the following equation (4). Then, the vertical filter information generation unit 160A outputs the vertical filter information that is the designed filter information to the generation unit 160C.

  The horizontal filter information generation unit 160B generates a 4: 2: 2 format image from the filter information (horizontal downsampling filter information) used in the filter processing by the conversion unit 12A among the information included in the color difference signal information. : Design filter information used to convert the original image into 4 format. That is, the horizontal filter information generation unit 160B designs filter information used for obtaining an original image in 4: 4: 4 format by performing horizontal upsampling processing on an image in 4: 2: 2 format. The design of the filter information is performed using the following equation (4). Then, the horizontal filter information generation unit 160B outputs the horizontal filter information that is the designed filter information to the generation unit 160C.

  Expression (4) is a filter calculation formula used by the vertical filter information generation unit 160A and the horizontal filter information generation unit 160B when designing the filter.

  Specifically, the equation (4) is obtained by upsampling a one-dimensional image and a color difference component in each pixel constituting the one-dimensional image by double, and then down-sampling the color difference component in each pixel by half. This is an expression for designing the filter information so that the obtained image becomes an image having the same image quality.

In Expression (4), D is a vector indicating a downsampling filter coefficient, and d _{1 to} d _2n (n is an integer of 1 or more) indicates a filter coefficient of the downsampling filter. U and V are vectors indicating up-sampling filter coefficients, u _{1 to} u _n (n is an integer of 1 or more) indicate filter coefficients used for up-sampling for the top field, and v _{1 to} v _n (n Is an integer of 1 or more) indicates a filter coefficient used for upsampling for the bottom field.

  In Expression (4), X is a matrix of 2n rows (2n-1) columns having upsampling filter coefficients as elements, and I is 2n-1 elements, the nth is 1 and the remaining is 0. It is a vector.

  Then, filter information is designed by designing D, U, and V so as to satisfy DX = I.

  By using Expression (4), the corresponding upsampling filter coefficient can be obtained from the downsampling filter coefficient. Conversely, the corresponding downsampling filter coefficient can also be obtained from the upsampling filter coefficient.

  The generation unit 160C generates color difference conversion information. Specifically, the generation unit 160C uses the color difference format (4: 2: 0 format) of the reference image received from the encoding unit 14 as the first color difference format of the encoded data encoded by the encoding unit 14. In addition, the generation unit 160C reads the second color difference format from a memory (not shown). Further, the generation unit 160C uses the vertical filter information received from the vertical filter information generation unit 160A and the horizontal filter information received from the horizontal filter information generation unit 160B as the specific information. The generation unit 160C generates color difference conversion information including the first color difference format, the second color difference format, and the specific information, and outputs the color difference conversion information to the NAL unit generation unit 18.

  As described above, in encoding apparatus 10A of the present embodiment, generation unit 160 receives the filter information used in conversion unit 120 as color difference signal information. The generation unit 160 generates color difference conversion information using the received color difference signal information.

  Therefore, when reproducing the decoded image obtained by decoding the encoded data encoded by the encoding device 10A, the encoded data of the first color difference format is used by using the filter information specified by the specific information included in the color difference conversion information. By converting the decoded image into the second color difference format, it is possible to suppress image quality deterioration due to resolution conversion.

  Therefore, even when the color difference conversion information is generated by a method different from that of the first embodiment, the same effect as that of the first embodiment can be obtained.

  Moreover, in addition to the effect by the encoding apparatus 10 in Embodiment 1, the structure of the production | generation part 160 (generation part 16) can be simplified.

(Modification 2)
In the above-described embodiment, the conversion unit 12 includes two conversion units (the conversion unit 12A and the conversion unit 12B), and the case where the resolution of the color difference component is converted a plurality of times for the original image has been described. However, the conversion unit 12 may be a functional unit that performs one color difference conversion. Further, in the above-described embodiment, the case where the conversion unit 12 performs the filter process (down sampling) for reducing the resolution of the color difference component has been described. However, the conversion unit 12 may perform filter processing (upsampling) that enlarges the resolution of the color difference component.

  In this case, as illustrated in FIG. 19, the encoding device 10A includes a conversion unit 122 instead of the conversion unit 120, and includes a generation unit 162 instead of the generation unit 160.

  FIG. 21 is a schematic diagram illustrating a functional configuration of the conversion unit 122. The conversion unit 122 includes a conversion unit 122A and an output adjustment unit 122B.

  For example, the conversion unit 122 accepts an original image in 4: 2: 0 format as an original image. The converter 122A converts the received 4: 2: 0 format original image into a 4: 2: 2 format image. The conversion unit 122A performs filter processing using filter information for performing pixel interpolation in the vertical direction on the color difference components of the pixels constituting the 4: 2: 0 format original image. Accordingly, the conversion unit 122A performs upsampling for interpolating in the vertical direction the color difference components of the pixels constituting the 4: 2: 0 format image. That is, the conversion unit 122A converts the 4: 2: 0 format original image into a 4: 2: 2 format image. The converter 122A outputs the converted 4: 2: 2 format image to the output adjuster 122B.

  The output adjustment unit 122B has a range in which each pixel value constituting the 4: 2: 2 format image received from the conversion unit 122A is not less than the minimum value determined in the standard and not more than the maximum value determined in the standard. Clipping processing is performed so that Then, the original image after the clipping process is output to the encoding unit 14 as a color difference converted image obtained by color difference conversion by the conversion unit 122.

  In addition, the output adjustment unit 122B outputs the color difference signal information including the filter information used for the filter processing by the conversion unit 122A to the generation unit 162.

  Next, the generation unit 162 will be described.

  FIG. 22 is a schematic diagram illustrating a functional configuration of the generation unit 162.

  The generation unit 162 includes a horizontal filter information generation unit 162A and a generation unit 162B.

  The horizontal filter information generation unit 162A receives the filter information (horizontal upsampling filter information) used for the filter processing by the conversion unit 122A as the color difference signal information.

  The horizontal filter information generation unit 162A designs the filter information used to convert the 4: 2: 2 format image into the 4: 2: 0 format from the horizontal upsampling filter information used in the filter processing by the conversion unit 122A. . That is, the horizontal filter information generation unit 162A designs the filter information used to obtain the 4: 2: 0 format image by performing the horizontal downsampling process on the 4: 2: 2 format image. Then, the horizontal filter information generation unit 162A outputs the horizontal filter information that is the designed filter information to the generation unit 162B.

  The generation unit 162B generates color difference conversion information. Specifically, the generation unit 162B uses the color difference format (4: 2: 2 format) of the reference image received from the encoding unit 14 as the first color difference format of the encoded data encoded by the encoding unit 14. Further, the generation unit 162B reads the second color difference format from a memory (not shown). Further, the generation unit 162B uses the horizontal filter information received from the horizontal filter information generation unit 162A as the specific information.

  The generation unit 162B generates color difference conversion information including the first color difference format, the second color difference format, and the specific information, and outputs the color difference conversion information to the NAL unit generation unit 18.

  As described above, even when the conversion unit 122 performs the filtering process (upsampling) for enlarging the resolution of the color difference component, the generation unit 162 selects the first color difference format, the second color difference format, and the specific information. Including color difference conversion information is generated.

  Therefore, also in this modification, the same effect as in the first embodiment can be obtained.

(Modification 3)
In the above-described embodiment, the case where the encoding device 10 and the encoding device 10A perform the color difference conversion has been described. There may be.

  FIG. 23 is a schematic diagram illustrating a functional configuration of the encoding device 10B.

  The encoding device 10B includes an encoding unit 14, a NAL unit generation unit 18, a transmission information generation unit 20, and a generation unit 16.

  The encoding device 10B has the same configuration as that of the encoding device 10 of the first embodiment except that the encoding device 10B does not include the conversion unit 12. In the present embodiment, the encoding unit 14 of the encoding device 10B receives a color difference converted image from an external device or the like. Further, the generation unit 16 receives color difference conversion information from an external device or the like.

  As described above, the encoding device 10 </ b> B may be configured not to include the conversion unit 12.

(Embodiment 3)
In this embodiment, a decoding device will be described. The decoding device is a device that decodes encoded data included in transmission information generated by the encoding devices 10, 10A, and 10B.

  FIG. 24 is a schematic diagram illustrating a functional configuration of the decoding device according to the present embodiment. The decoding device 50 according to the present embodiment includes a transmission information decoding unit 52, a NAL unit decoding unit 54, a decoding unit 56, a decoding unit 58, and a conversion unit 60.

  The transmission information decoding unit 52 receives transmission information. In the present embodiment, as an example, a case where transmission information is received from encoding apparatus 10 of Embodiment 1 will be described. Further, in the present embodiment, a case will be described in which transmission information including the color difference conversion information illustrated in FIG. 5 is received from the encoding device 10. The transmission information decoding unit 52 generates NAL unit information from the received transmission information.

  The NAL unit decoding unit 54 receives NAL unit information from the transmission information decoding unit 52 and decodes it. Thereby, the NAL unit decoding unit 54 obtains encoded data, color difference conversion information, byte alignment information, and the like.

  The NAL unit decoding unit 54 outputs the encoded data obtained from the NAL unit information to the decoding unit 56. Further, the NAL unit decoding unit 54 outputs the color difference conversion information obtained from the NAL unit information to the decoding unit 58.

  The decoding unit 58 decodes the color difference conversion information to obtain a first color difference format, a second color difference format, and specific information. And it outputs to the conversion part 60.

  FIG. 25 is a schematic diagram illustrating a functional configuration of the decoding unit 58.

  As shown in FIG. 25, the decoding unit 58 includes a decoding unit 58A. The decoding unit 58A analyzes the color difference conversion information, and reads the first color difference format, the second color difference format, and the specific information included in the color difference conversion information. Then, the read color difference conversion information including the first color difference format, the second color difference format, and the specific information is output to the conversion unit 60.

  If the specific information included in the color difference conversion information is filter information used when converting the decoded image in the first color difference format into the second color difference format, the decoding unit 58A The information is output to the conversion unit 60 as it is.

  On the other hand, when the specific information included in the color difference conversion information is identification information of filter information used when converting the decoded image of the first color difference format into the second color difference format, the decoding unit 58A corresponds to the identification information. The filter information to be read is read from definition information stored in advance in a memory not shown. Then, the read filter information is output to the conversion unit 60 as specific information.

  Further, when the specific information included in the color difference conversion information is the filter information used for the filter processing in the conversion unit 12 of the encoding device 10, the decoding unit 58A decodes the first color difference format from the filter information. Design filter information for converting the image to the second color difference format. Then, the filter information of the designed filter is output to the conversion unit 60 as specific information.

  Returning to FIG. 24, the decoding unit 56 decodes the encoded data to obtain a decoded image. The decoding unit 56 outputs the decoded image to the conversion unit 60.

  FIG. 26 is a schematic diagram illustrating a functional configuration of the decoding unit 56.

  As illustrated in FIG. 26, the decoding unit 56 includes an entropy decoding unit 56A, an inverse quantization / inverse transformation unit 56B, an addition unit 56C, a frame memory 56D, and a predicted image generation unit 56E.

  The entropy decoding unit 56A accepts encoded data from the NAL unit decoding unit 54. The entropy decoding unit 56A entropy decodes the received encoded data according to a predetermined syntax. Thereby, the entropy decoding unit 56A obtains quantization coefficients and motion vector information.

  The entropy decoding unit 56A outputs the quantized coefficient to the inverse quantization / inverse transform unit 56B, and outputs the motion vector information to the predicted image generation unit 56E.

  The inverse quantization / inverse transform unit 56B inversely quantizes the quantization coefficient and then inversely transforms it to generate an error image. The adding unit 56C receives the error image from the inverse quantization / inverse transform unit 56B and receives the predicted image from the predicted image generation unit 56E. Then, the adding unit 56C adds the error image and the predicted image to generate a decoded image. The decoded image is stored in the frame memory 56D and then output to the conversion unit 60 and the predicted image generation unit 56E.

  The predicted image generation unit 56E generates a predicted image using the decoded image and motion vector information. Then, the predicted image generating unit 56E outputs the generated predicted image to the adding unit 56C.

  Returning to FIG. 24, the conversion unit 60 receives the decoded image from the decoding unit 56. Further, the conversion unit 60 receives color difference conversion information from the decoding unit 58. The conversion unit 60 reads the first color difference format, the second color difference format, and the specific information included in the color difference conversion information. Then, the conversion unit 60 converts the resolution of the color difference component with respect to the decoded image of the first color difference format using the filter specified by the specific information, and converts it to the second color difference format. The conversion unit 60 outputs a reproduction image obtained by converting the resolution of the color difference component of the decoded image to a reproduction device or the like.

  FIG. 27 is a schematic diagram illustrating a functional configuration of the conversion unit 60.

  The conversion unit 60 includes a conversion unit 60A, a conversion unit 60B, and an output adjustment unit 60C.

  The conversion unit 60A converts the decoded image in the 4: 2: 0 format into the 4: 2: 2 format. From the color difference conversion information received from the decoding unit 58, the conversion unit 60A reads the filter information used for the filter processing by the conversion unit 12B as specific information. Then, filter processing is performed using the read filter information, and the decoded image in the 4: 2: 0 format is converted into the 4: 2: 2 format.

  The conversion unit 60A outputs the 4: 2: 2 format decoded image obtained by the conversion to the conversion unit 60B. From the color difference conversion information received from the decoding unit 58, the conversion unit 60B reads the filter information used for the filter process by the conversion unit 12A as specific information. Then, filter processing is performed using the read filter information, and a 4: 2: 2 format decoded image is converted into a 4: 4: 4 format. The conversion unit 60B outputs the converted 4: 4: 4 format decoded image to the output adjustment unit 60C.

  The output adjustment unit 60C reads the pixel bit length at the time of reproduction, the maximum value of the color difference component at the time of reproduction, the minimum value of the color difference component at the time of reproduction specified by the color difference conversion information, or a predetermined color difference format The decoded image is clipped so as to satisfy these values with the pixel bit length, the maximum value, and the minimum value according to the specifications. Then, the decoded image after the clipping process is output as a reproduced image.

  Next, a decoding process executed by the decoding device 50 will be described.

  FIG. 28 is a flowchart showing the procedure of the decoding process executed by the decoding device 50.

  First, the transmission information decoding unit 52 decodes the transmission information received from the encoding device 10 (step S200). NAL unit information is obtained by the process of step S200.

  Next, the NAL unit decoding unit 54 decodes the NAL unit information obtained in step S200 (step S202). The NAL unit decoding unit 54 obtains encoded data, color difference conversion information, byte alignment information, and the like by the processing in step S202.

  Next, the decoding unit 56 decodes the encoded data received from the NAL unit decoding unit 54 to obtain a decoded image (step S204).

  Next, the decoding unit 58 decodes the color difference conversion information (step S206). By the processing in step S206, the decoding unit 58 reads the first color difference format, the second color difference format, and the specific information included in the color difference conversion information. Then, the read color difference conversion information including the first color difference format, the second color difference format, and the specific information is output to the conversion unit 60.

  Next, the conversion unit 60 performs color difference conversion on the decoded image received from the decoding unit 56 into the second color difference format defined in the color difference conversion information (step S208). The conversion unit 60 outputs a reproduction image obtained by performing color difference conversion on the decoded image to a reproduction device or the like. Then, this routine ends.

  As described above, the decoding device 50 receives transmission information including color difference conversion information and encoded data. Then, the decoding device 50 converts the decoded image of the first color difference format obtained by decoding the encoded data into the second color difference format using the filter specified by the specific information included in the color difference conversion information. . For this reason, the decoding apparatus 50 can suppress image quality deterioration due to resolution conversion.

  Therefore, the decoding device 50 according to the present embodiment can suppress image quality deterioration.

(Modification 4)
Next, operations of the decoding unit 58 and the decoding unit 58A (see FIG. 25) when the transmission information decoding unit 52 receives transmission information including the color difference conversion information illustrated in FIG. 8 from the encoding device 10 will be described.

  In this case, the decoding unit 58A decodes the color difference conversion information according to the syntax shown in FIG.

  As described above, chroma_loc_info_present_flag in the color difference conversion information illustrated in FIG. 8 is a flag indicating whether or not there is filter information regarding the pixel position of the color difference signal and color difference conversion. When the value of chroma_loc_info_present_flag is “0”, the decoding unit 58A considers that there is no filter information regarding the pixel position and color difference conversion of the color difference signal, and skips reading. On the other hand, when the value of chroma_loc_info_present_flag is “1”, there is filter information relating to the pixel position of the color difference signal and color difference conversion. For this reason, in this case, the decoding unit 58A specifies the pixel sample position of the color difference using values indicated by each of chroma_sample_loc_type_top_field and chroma_sample_loc_type_bottom_field.

  Further, as described above, chroma_filter_info_present_flag is a flag indicating whether or not filter information regarding color difference conversion exists. Therefore, when the value of chroma_filter_info_present_flag is “0”, the decoding unit 58A skips reading because there is no filter information regarding color difference conversion. On the other hand, when the value of chroma_filter_info_present_flag is “1”, filter information regarding color difference conversion exists. Therefore, in this case, the decoding unit 58A reads the identification information (Value) indicated by chroma_filter_info from the color difference conversion filter definition information shown in FIG. 9 or FIG.

  Specifically, the decoding unit 58A, in the color difference conversion filter definition information illustrated in FIG. 9 or FIG. 10, corresponds to the identification information, the filter coefficient, the number of denominators when performing the filtering process (Divisor), and after the filtering process. Information corresponding to each of the sample position (Phase shift) of the color difference pixel, the use of the filter coefficient, and the information (Purpose) of the second color difference format.

  The color difference conversion filter definition information shown in FIG. 9 and FIG. 10 includes a pair of encoding devices other than the filter coefficients for performing the color difference conversion from the first color difference format to the second color difference format as described above. Also included is a filter coefficient used for color difference conversion from the second color difference format to the first color difference format.

  Specifically, when the value of chroma_filter_info in the color difference conversion filter definition information shown in FIG. 10 is “1”, the decoding unit 58A follows the syntax shown in FIG. 11 and the target_format_idc that is the second color difference format, and the color difference conversion. Each value of num_of_filter_minus1 indicating the value of the number of filters minus 1 and filter_coeff indicating the filter coefficient are read.

  Then, the decoding unit 58A outputs these read values to the conversion unit 60. The processing of the conversion unit 60 is the same as described above.

  As described above, also when the transmission information including the color difference conversion information illustrated in FIG. 8 is received, the decoding device 50 similarly uses the filter specified by the specific information included in the color difference conversion information to convert the encoded data. The decoded image of the first color difference format obtained by decoding is subjected to color difference format conversion. For this reason, the decoding apparatus 50 can suppress image quality deterioration due to resolution conversion.

(Modification 5)
Next, operations of the decoding unit 58 and the decoding unit 58A (see FIG. 25) when the transmission information decoding unit 52 receives transmission information including the color difference conversion information illustrated in FIG. 12 from the encoding device 10 will be described.

  In this case, the decoding unit 58A decodes the color difference conversion information according to the syntax shown in FIG.

  As described above, chroma_loc_info_present_flag in the color difference conversion information shown in FIG. 12 is a flag indicating whether or not there is filter information regarding the pixel position of the color difference signal and color difference conversion. When the value of chroma_loc_info_present_flag is “0”, there is no filter information regarding the pixel position and color difference conversion of the color difference signal, and thus the decoding unit 58A skips the value of this flag.

  On the other hand, when the value of chroma_loc_info_present_flag is “1”, there is filter information relating to the pixel position of the color difference signal and color difference conversion. For this reason, in this case, the decoding unit 58A specifies the pixel sample position of the color difference from the values of chroma_sample_loc_type_top_field and chroma_sample_loc_type_bottom_field.

  chroma_filter_info_present_flag is a flag indicating whether or not filter information relating to color difference conversion exists. When the value of chroma_filter_info_present_flag is “1”, the decoding unit 58A performs decoding according to the syntax of the color difference conversion filter information of FIG. 13, FIG. 15, or FIG.

  Hereinafter, the case where the decoding unit 58A performs decoding according to the syntax of the color difference conversion filter information illustrated in FIG. 13 will be described.

  As described above, num_of_filter_set_minus1 is a value indicating the number of filter sets minus 1, and indicates that loop processing is performed by the number of filter sets. Further, implicit_filter_set_flag is a flag indicating that information of a predetermined filter set is used. When this flag is “1”, the decoding unit 58A reads filter_set_idc, which is identification information of filter set information defined in advance. On the other hand, when the implicit_filter_set_flag is “0”, the decoding unit 58A reads num_of_filter_minus1 indicating the value of the number of color difference conversion filters minus 1 and performs the following loop of the number of color difference conversion filters.

  As described above, implicit_filter_flag is a flag indicating that predetermined filter information is used. When the value of this flag is “1”, the decoding unit 58A reads filter_idc that is identification information of filter information defined in advance. On the other hand, when the value of implicit_filter_flag is “0”, the decoding unit 58A reads tap_length_minus1 indicating the value of the filter coefficient tap length minus 1. Then, the decoding unit 58A performs a loop for the read filter coefficient tap length, and reads filter_coeff representing the filter coefficient value.

  Next, the decoding unit 58A, the filter coefficient tap length of the predefined color difference conversion filter definition information corresponding to filter_set_idc and filter_idc, the filter coefficient (Filter coefficient), and the number of denominators when performing filter processing ( (Division), the sample position (Phase shift) of the color difference pixel after the filter processing, the use of the filter coefficient, and the second color difference format information (Purpose) are read. Note that filter_set_idc can also define a filter coefficient in the filter processing on the encoding side that is paired with the filter processing on the decoding side.

  Then, the decoding unit 58A outputs these read values to the conversion unit 60. The processing of the conversion unit 60 is the same as described above.

  Similarly, when receiving transmission information including the color difference conversion information shown in FIG. 12, similarly, the decoding device 50 uses the filter specified by the specific information included in the color difference conversion information to convert the encoded data. The decoded image of the first color difference format obtained by decoding is subjected to color difference format conversion. For this reason, the decoding apparatus 50 can suppress image quality deterioration due to resolution conversion.

(Modification 6)
Next, the case where the decoding unit 58A performs decoding according to the syntax of the color difference conversion filter information illustrated in FIG.

  As described above, target_format_idc indicates the second color difference format. Further, chroma_format_idc indicates the first color difference format.

  When the value of chroma_format_idc is “1” and the value of target_format_idc is larger than “1”, or when the value of chroma_format_idc is larger than “1” and the value of target_format_idc is “1”, the decoding unit 58A is Read direction filter information.

  As described above, implicit_vertical_flag is a flag indicating that vertical filter information defined in advance is used. When the value of this flag is “1”, the decoding unit 58A reads vertical_filter_idc which is identification information of vertical filter information defined in advance. On the other hand, when the value of implicit_vertical_flag is “0”, the decoding unit 58A reads tap_length_vertical_minus1 indicating the value of the tap length minus 1 of the filter coefficient in the vertical direction, and reads the vertical filter coefficient ver_filter_coeff for the tap length.

  Then, when the encoded data is a field signal, the decoding unit 58A reads second_filter_flag that is a flag defined when different filter sets are used in the vertical direction in the top field and the bottom field. If the value of this flag is “1”, the value of chroma_format_idc is “1”, and the value of target_format_idc is greater than “1”, the second filter information exists.

  On the other hand, when the value of the implicit_vertical_flag is “1”, the decoding unit 58A reads second_vertical_filter_idc, which is identification information of the second vertical filter information defined in advance. When the value of the implicit_vertical_flag is “0”, the decoding unit 58A reads tap_length_second_vertical_minus1 indicating the value of the tap length minus 1 of the second vertical filter coefficient, and reads the vertical filter coefficient second_vert_filter_coeff for the tap length. .

  Further, when the value of chroma_format_idc is “1” or “2” and the value of target_format_idc is “3”, or the value of chroma_format_idc is “3” and target_format_idc is “1” or “ In the case of “2”, the decoding unit 58A reads the filter information in the horizontal direction.

  The implicit_horizontal_flag is a flag indicating that predefined horizontal filter information is used. When the value of this flag is “1”, the decoding unit 58A reads the horizontal_filter_idc that is the identification information of the predefined filter information in the horizontal direction. On the other hand, when the value of implicit_vertical_flag is “0”, the decoding unit 58A reads tap_length_horizontal_minus1 indicating the value of the tap length minus 1 of the filter coefficient in the horizontal direction, and reads the horizontal filter coefficient hor_filter_coeff for the tap length.

  Then, the decoding unit 58A specifies the filter_idc in FIG. 16 corresponding to the vertical_filter_idc, the second_vertical_filter_idc, or the horizontal_filter_idc shown in FIG. Then, the decoding unit 58A corresponds to the specified filter_idc, the tap length (Tap length) of the filter coefficient of the predefined color difference conversion filter definition information, the filter coefficient (Filter coefficients), and the number of denominators when performing the filtering process ( Divider), the sample position (Phase shift) of the color difference pixel after the filter processing, the use of the filter coefficient and the information of the second color difference format (Purpose).

  Then, the decoding unit 58A outputs these read values to the conversion unit 60. The processing of the conversion unit 60 is the same as described above.

  Similarly, when decoding is performed according to the syntax of the color difference conversion filter information shown in FIG. 14, the decoding device 50 uses the filter specified by the specific information included in the color difference conversion information to perform encoding. The decoded image of the first color difference format obtained by decoding the data is subjected to color difference format conversion. For this reason, the decoding apparatus 50 can suppress image quality deterioration due to resolution conversion.

(Modification 7)
Next, a case where the decoding unit 58A performs decoding according to the syntax of the color difference conversion filter information illustrated in FIG.

  When the value of chroma_format_idc is “1” and the value of target_format_idc is larger than “1”, or when the value of chroma_format_idc is larger than “1” and target_format_idc is “1”, the decoding unit 58A is in the vertical direction. Read filter information for.

  Specifically, the decoding unit 58A reads tap_length_vertical_minus1 indicating the value of the tap length minus 1 of the filter coefficient in the vertical direction, and reads the vertical filter coefficient ver_filter_coeff for the tap length.

  When the encoded data is a field signal, the decoding unit 58A reads second_filter_flag that is a flag defined when different filter sets are used in the vertical direction in the top field and the bottom field. Then, when the value of this flag is “1”, the value of chroma_format_idc is “1”, and the value of target_format_idc is greater than “1”, the second filter information exists.

  Therefore, in this case, the decoding unit 58A reads tap_length_second_vertical_minus1 indicating the value of the tap length minus 1 of the second vertical filter coefficient, and reads the vertical filter coefficient second_ver_filter_coeff for the tap length.

  On the other hand, if the value of chroma_format_idc is “1” or “2” and the value of target_format_idc is “3”, or the value of chroma_format_idc is “3” and target_format_idc is “1” or “ In the case of “2”, the decoding unit 58A reads the filter information in the horizontal direction.

  Tap_length_horizontal_minus1 indicating the value of the tap coefficient minus 1 of the filter coefficient in the horizontal direction is read, and the horizontal filter coefficient hor_filter_coeff for the tap length is read.

  Then, the decoding unit 58A outputs these read values to the conversion unit 60. The processing of the conversion unit 60 is the same as described above.

  As described above, when decoding is performed according to the syntax of the color difference conversion filter information illustrated in FIG. 17, similarly, the decoding device 50 performs encoding using the filter specified by the specific information included in the color difference conversion information. The decoded image of the first color difference format obtained by decoding the data is subjected to color difference format conversion. For this reason, the decoding apparatus 50 can suppress image quality deterioration due to resolution conversion.

(Modification 8)
Next, a specific description will be given of a case where the decoding device 50 receives transmission information including the filter information used for the filter processing in the conversion unit 12 of the encoding device 10 as specific information.

  In this case, the decoding device 50 illustrated in FIG. 24 may be configured to include the decoding unit 580 instead of the decoding unit 58.

  FIG. 29 is a schematic diagram illustrating a functional configuration of the decoding unit 580. The decoding unit 580 includes a decoding unit 580A, a vertical filter information generation unit 580B, and a horizontal filter information generation unit 580C.

  The decoding unit 580A analyzes the color difference conversion information, and reads the first color difference format, the second color difference format, and the specific information included in the color difference conversion information. In this modification, the specific information is filter information used for the filter processing in the conversion unit 12 of the encoding device 10. In this modification, the specific information includes vertical downsampling filter information and horizontal downsampling filter information.

  The vertical filter information generation unit 580B generates vertical upsampling filter information used at the time of filter processing by the conversion unit 60 of the decoding device 50 from the vertical downsampling filter information included in the specific information. The horizontal filter information generation unit 580C generates horizontal upsampling filter information used at the time of filter processing by the conversion unit 60 of the decoding device 50 from the horizontal downsampling filter information included in the specific information. The decoding unit 580 includes the vertical upsampling filter information generated by the vertical filter information generation unit 580B, the horizontal upsampling filter information generated by the horizontal filter information generation unit 580C, the first color difference format, and the second color difference. The color difference conversion information including the format is output to the conversion unit 60.

  The conversion unit 60 reads the first color difference format, the second color difference format, and the specific information included in the color difference conversion information as in the above embodiment. Then, the conversion unit 60 converts the resolution of the color difference component with respect to the decoded image of the first color difference format using the filter specified by the specific information, and converts it to the second color difference format. The conversion unit 60 outputs a reproduction image obtained by converting the resolution of the color difference component of the decoded image to a reproduction device or the like.

  In this way, the filter information used for the filter processing of the conversion unit 60 of the decoding device 50 may be generated on the decoding device 50 side.

  It is assumed that the specific information included in the color difference conversion information generated by the decoding unit 58 or the decoding unit 580 includes vertical downsampling filter information.

  In this case, the decoding device 50 includes a conversion unit 600 instead of the conversion unit 60.

  FIG. 30 is a schematic diagram illustrating a functional configuration of the conversion unit 600.

  The conversion unit 600 includes a conversion unit 600A and an output adjustment unit 600B.

  The converter 600A accepts a 4: 2: 2 format decoded image from the decoder 56. The converting unit 600A uses the vertical downsampling filter information indicated by the specific information included in the color difference conversion information received from the decoding unit 58 or the decoding unit 580 for the received 4: 2: 2 format decoded image. Color difference conversion to 2: 0 format. In other words, the conversion unit 600A performs downsampling that is thinned down to 1/2 in the vertical direction, using the vertical downsampling filter information, for the color difference components of the pixels constituting the decoded image of 4: 2: 2 format. Conversion unit 600A outputs the decoded 4: 2: 0 format decoded image to output adjustment unit 600B.

  The output adjustment unit 600B reads the pixel bit length at the time of reproduction, the maximum value of the color difference component at the time of reproduction, the minimum value of the color difference component at the time of reproduction specified by the color difference conversion information, or a predetermined color difference format The decoded image is clipped so as to satisfy these values with the pixel bit length, the maximum value, and the minimum value according to the specifications. Then, the decoded image after the clipping process is output as a reproduction image to be reproduced.

(Embodiment 4)
Next, the hardware configuration of the encoding devices 10, 10A, and 10B and the decoding device 50 will be described. FIG. 31 is a block diagram illustrating hardware configurations of the encoding devices 10, 10 </ b> A, and 10 </ b> B and the decoding device 50.

  The encoding devices 10, 10A, and 10B and the decoding device 50 according to the present embodiment include a communication interface (IF) 86, a CPU 80 (Central Processing Unit), a ROM (Read Only Memory) 82, and a RAM (Random Access Memory) 84. Are interconnected by a bus and have a hardware configuration using a normal computer.

  The CPU 80 is an arithmetic device that controls overall processing in each of the encoding devices 10, 10 </ b> A, and 10 </ b> B, and the decoding device 50. The RAM 84 stores data necessary for various processes performed by the CPU 80. The ROM 82 stores programs and the like that realize various processes by the CPU 80. The communication interface (IF) 86 is an interface for connecting to an external device via a communication line and transmitting / receiving data to / from the connected external device.

  A program for executing the encoding process executed by the encoding devices 10, 10A, and 10B and a program for executing the decoding process executed by the decoding device 50 are provided by being incorporated in advance in the ROM 82 or the like. The

  Note that the program for executing the encoding process executed by the encoding devices 10, 10A, and 10B and the program for executing the decoding process executed by the decoding device 50 are the encoding devices 10, 10A, and 10B. , And a file in a format that can be installed in the decoding device 50 or an executable format, and is recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disk). It may be configured to be provided.

  In addition, the program for executing the encoding process executed by the encoding devices 10, 10A, and 10B and the program for executing the decoding process executed by the decoding device 50 are connected to a network such as the Internet. It may be configured to be provided by being stored on a computer and downloaded via a network. Also, a program for executing the encoding process executed by the encoding devices 10, 10A, and 10B and a program for executing the decoding process executed by the decoding device 50 are provided via a network such as the Internet. It may be configured to be distributed.

  The program for executing the encoding process executed by the encoding devices 10, 10 </ b> A, and 10 </ b> B and the program for executing the decoding process executed by the decoding device 50 have a module configuration including the above-described units. Yes. As actual hardware, the CPU 80 reads out and executes various programs from the ROM 82 and the like, whereby the above-described units are loaded onto the main storage device, and the above-described functional configuration is generated on the main storage device. Yes.

  As mentioned above, although some embodiment and modification of this invention were demonstrated, these embodiment and modification are shown as an example, and are not intending limiting the range of invention. These novel embodiments and modifications can be implemented in various other forms, and various omissions, replacements, and conversions can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10, 10A, 10B Encoding device 14 Encoding unit 16, 160, 162 Generation unit 50 Decoding device

Claims (6)

A first chrominance format indicating the resolution of the chrominance component of the encoded data, the chrominance component used when reproducing the decoded image obtained by decoding the encoded data, and generated in accordance with a predetermined syntax; A reception unit that receives transmission information including: a second color difference format indicating resolution; and filter specifying information for specifying a filter used when converting the color difference format of the decoded image;
A decoding unit that generates the decoded image by decoding the encoded data included in the transmission information;
A conversion unit for converting the decoded image into a color difference format using the filter indicated by the filter specifying information;
With
The first color difference format indicates a resolution of a color difference component of 4: 2: 2 format or 4: 4: 4 format and the second color difference format indicates a resolution of a color difference component of 4: 2: 0 format; or The first color difference format indicates the resolution of the color difference component of 4: 4: 4 format and the second color difference format indicates the resolution of the color difference component of 4: 2: 0 format or 4: 2: 2 format;
The filter specifying information includes a filter coefficient,
The conversion unit includes at least one of a horizontal downsampling filter and a vertical downsampling filter among a plurality of predetermined filters based on the filter coefficient, the first color difference format, and the second color difference format. A filter is selected, and the decoded image is subjected to color difference format conversion using the selected filter.
Decoding device. A first chrominance format indicating the resolution of the chrominance component of the encoded data, the chrominance component used when reproducing the decoded image obtained by decoding the encoded data, and generated in accordance with a predetermined syntax; A reception unit that receives transmission information including a second color difference format indicating resolution, and filter information for specifying a filter used when converting the color difference format of the decoded image;
A decoding unit that generates the decoded image by decoding the encoded data included in the transmission information;
A conversion unit for converting the decoded image into a color difference format using a filter indicated by the filter information;
With
The first color difference format indicates a resolution of a color difference component of 4: 2: 2 format or 4: 4: 4 format and the second color difference format indicates a resolution of a color difference component of 4: 2: 0 format; or The first color difference format indicates the resolution of the color difference component of 4: 4: 4 format and the second color difference format indicates the resolution of the color difference component of 4: 2: 0 format or 4: 2: 2 format;
The filter information includes filter identification information,
The conversion unit includes at least one of a horizontal downsampling filter and a vertical downsampling filter among a plurality of predetermined filters based on the identification information, the first color difference format, and the second color difference format. A filter is selected, and the decoded image is subjected to color difference format conversion using the selected filter.
Decoding device. An encoding unit for generating encoded data;
In accordance with a predetermined syntax, a first color difference format indicating the resolution of the color difference component of the encoded data, a second color difference format indicating the resolution of the color difference component used when reproducing the decoded image obtained by decoding the encoded data, And a generation unit for generating filter information for specifying a filter used at the time of color difference format conversion of the decoded image,
An output unit that outputs transmission information including the encoded data, the first color difference format, the second color difference format, and the filter information;
With
The first color difference format indicates a resolution of a color difference component of 4: 2: 2 format or 4: 4: 4 format and the second color difference format indicates a resolution of a color difference component of 4: 2: 0 format; or The first color difference format indicates the resolution of the color difference component of 4: 4: 4 format and the second color difference format indicates the resolution of the color difference component of 4: 2: 0 format or 4: 2: 2 format;
Encoding device. A first chrominance format indicating the resolution of the chrominance component of the encoded data, the chrominance component used when reproducing the decoded image obtained by decoding the encoded data, and generated in accordance with a predetermined syntax; A reception step of receiving transmission information including: a second color difference format indicating resolution; and filter specifying information for specifying a filter used at the time of color difference format conversion of the decoded image;
A decoding step of decoding the encoded data included in the transmission information to generate the decoded image;
A conversion step of converting the decoded image into a color difference format using a filter indicated by the filter specifying information;
Including
The first color difference format indicates a resolution of a color difference component of 4: 2: 2 format or 4: 4: 4 format and the second color difference format indicates a resolution of a color difference component of 4: 2: 0 format; or The first color difference format indicates the resolution of the color difference component of 4: 4: 4 format and the second color difference format indicates the resolution of the color difference component of 4: 2: 0 format or 4: 2: 2 format;
The filter specifying information includes a filter coefficient,
The converting step includes at least one of a horizontal downsampling filter and a vertical downsampling filter among a plurality of predetermined filters based on the filter coefficient, the first color difference format, and the second color difference format. A filter is selected, and the decoded image is subjected to color difference format conversion using the selected filter.
Decryption method. A first chrominance format indicating the resolution of the chrominance component of the encoded data, the chrominance component used when reproducing the decoded image obtained by decoding the encoded data, and generated in accordance with a predetermined syntax; A reception step of receiving transmission information including: a second color difference format indicating resolution; and filter information for specifying a filter used when converting the color difference format of the decoded image;
A decoding step of decoding the encoded data included in the transmission information to generate the decoded image;
A conversion step of converting the decoded image into a color difference format using a filter indicated by the filter information;
Including
The first color difference format indicates a resolution of a color difference component of 4: 2: 2 format or 4: 4: 4 format and the second color difference format indicates a resolution of a color difference component of 4: 2: 0 format; or The first color difference format indicates the resolution of the color difference component of 4: 4: 4 format and the second color difference format indicates the resolution of the color difference component of 4: 2: 0 format or 4: 2: 2 format;
The filter information includes filter identification information,
The converting step includes at least one of a horizontal downsampling filter and a vertical downsampling filter out of a plurality of predetermined filters based on the identification information of the filter information, the first color difference format, and the second color difference format. A color difference format conversion of the decoded image using the selected filter.
Decryption method. An encoding step for generating encoded data;
In accordance with a predetermined syntax, a first color difference format indicating the resolution of the color difference component of the encoded data, a second color difference format indicating the resolution of the color difference component used when reproducing the decoded image obtained by decoding the encoded data, And a generation step of generating filter information for specifying a filter used at the time of color difference format conversion of the decoded image;
An output step of outputting transmission information including the encoded data, the first color difference format, the second color difference format, and the filter information;
Including
The first color difference format indicates a resolution of a color difference component of 4: 2: 2 format or 4: 4: 4 format and the second color difference format indicates a resolution of a color difference component of 4: 2: 0 format; or The first color difference format indicates the resolution of the color difference component of 4: 4: 4 format and the second color difference format indicates the resolution of the color difference component of 4: 2: 0 format or 4: 2: 2 format;
Encoding method.

Images