JP3190118B2 - Image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus having storage means for storing image information, for example, an image output apparatus such as a printer, or an image coding apparatus having means for compressing and storing input image data. The present invention relates to an image processing apparatus that is most suitable for such purposes.

[0002]

2. Description of the Related Art Conventionally, when compressed data is stored in a page memory of a printer device, image data for one page is created, compressed in a lump, and stored in a page memory. Further, in this case, the image information of the gradation information for each pixel has a very large information amount of (number of pixels) × (number of gradation bits).

In recent years, printers that can output halftone images as multi-valued information without binarization have been put to practical use. For example, when such a printer is connected to a host computer to output an image, it is necessary to transfer image information in accordance with the process speed of the printing process of the printer. If the input color space information is Y, the color material
(Yellow), M (magenta), C (cyan), and K (black) are required to be converted into density information.

In order to solve the above problem, as shown in FIG. 25, a printer has a memory 81 of a maximum output size or larger, and input image information is temporarily stored in the memory 81. A device that stores and then transmits and outputs data to the printer engine 82 for the convenience of the printer has been put to practical use. A portion surrounded by a broken line indicates a printer (the same applies hereinafter).

[0005] Further, as shown in FIG.
Owning a smaller amount of memory 91 than the maximum output size,
The input image information is uniformly encoded by reducing the redundancy of the information by the compression processing unit 92 and stored in the memory 91. When the image information is output, it is decoded by the decompression processing unit 93 so that it is convenient for the printer. Was sent to the printer engine 94 and output.

Further, in an image coding apparatus in which image information is compressed and stored in a page memory, a fixed length processing in a block has been proposed by the present applicant as a compression method. In-block fixed-length processing is to divide an input image into n × n blocks, perform orthogonal transform on a block-by-block basis, and assign a fixed code length to an orthogonal transform component to be output. Means that the amount of code information output to each block is made equal between blocks. Therefore, when storing image data in a page memory with a limited procedure, the amount of information that can be allocated to one block is calculated from the ratio of one block to one page, and the amount of information is calculated as the amount of information. By performing the fixed length processing in the block, all the image data can be stored in the page memory. For example, if the image data of A3 is 8 × 8
If the block is divided into a total of N blocks when the page memory is M, the amount of information allocated to one block is M / N, and conversely, the information amount is blocked. If the internal fixed length processing is performed, the image of A3 can be stored in the page memory. FIG. 2 is a block diagram showing this conventional example. Image data is input from the input terminal 1 and
Blocked to × 8. Further, orthogonal transformation is performed on a block basis. In this conventional example, DCT (Discrete Cosine
Transform) circuit 3 is used. The DCT circuit 3 converts the image data into DCT coefficients,
Is performed. At this time, the quantization is performed based on the quantization table input from the quantization table 20. At this time, the quantization is performed so that each component in the block falls within the bit length determined by the bit allocation. For example, assuming that the bit precision of the DCT coefficient is 8 bits and a certain component is allocated to 4 bits, the DCT coefficient is divided by 16. Therefore, the relationship between the bit allocation table 21 for determining the bit allocation of each DCT component and the quantization table for suppressing the bit length is such that the bit precision of each DCT coefficient is C (C is an integer).
When bits of a certain DCT coefficient A _ij are distributed to B _ij , the quantization coefficient Q _ij of the component in the quantization table becomes 2 ＾ (C-B _ij ). A bit distribution table 21 and a quantization table 20 are created so as to satisfy this relationship.
However, the actual bit length of the data quantized by the quantization circuit 5 remains the same as the bit precision of the input DCT coefficient. Therefore, for example, if quantized data having a data length of 8 bits is input from the quantization circuit 5,
With respect to the components distributed in 4 bits by the bit distribution table 21, only the lower 4 bits of the 8-bit length are cut out and output. Further, the processing is performed for each component in the block, and the components are sequentially packed one-dimensionally with the bit lengths allocated by bits, and then output. Then, the data arranged one-dimensionally is sequentially stored in the page memory 10. In this way, the fixed length processing within the block is performed in accordance with the bit distribution determined for each block, and the block is compressed and stored in the page memory. Also, when expanding and outputting image data,
Data is read from the page memory 10, and the processing reverse to that at the time of compression is performed by the processing circuits 11, 12, 13, and 14 shown in FIG. Is output.

As described above, conventionally, as a method of compressing image information and storing it in a page memory, image data is divided into blocks, and fixed lengths are stored for each block in the page memory. A way to do that has been proposed.

[0008]

However, when compressed data is stored in the page memory of the printer, the data is conventionally compressed uniformly over one page.
It has the following disadvantages. (1) One page of image data is composed of a plurality of partial images as shown in FIG. 27, and when their characteristics are different, the optimal compression parameters are different, and the compression efficiency is reduced. . (2) Since blanks other than images are also regarded as image data, the amount of codes increases and redundancy increases. (3) When the compression is performed by the variable length coding method, the code amount is fixed in the page. Therefore, when the compression is performed by the one-pass method, the area differs between the beginning and the end of the page. The dignity falls. (4) The required image quality cannot be set for each partial image. (5) The compression parameter cannot be controlled by the attribute of each partial image.

However, in the above-described conventional example shown in FIG. 25, having a memory of the maximum output size or larger on the printer side is proportional to the maximum output size of the printer. This increases the memory capacity. So, considering the printer cost,
The ratio of the memory cost becomes very large. Further, in consideration of the configuration shown in FIG. 26, the compression ratio is determined in the compression processing unit 92 of the printer on the assumption that an image of the maximum output size of the printer will come.

For example, assuming that the capacity corresponding to the maximum output size of the printer is A and the capacity owned by the printer is B, no matter what size image is promoted, the compression ratio B
Only the fixed length coding of / A is possible. Also, variable-length coding is impossible because the code amount cannot be predicted and the code amount may exceed B.

For example, assume a case where orthogonal transform is used as a compression method. In the conventional method, the maximum output size of the printer is first divided into N × M (including N = M) and divided into X blocks. Then, the code amount is allocated to each block by B / X, and this is set as a reference code amount. Then, after the orthogonal transformation, a quantization process is performed so that each block falls within the reference code amount, and the quantization coefficient is encoded.

That is, regardless of the image size, the input image is blocked to N × M, and the code amount B / X
Fixed-length coding. With this method,
For example, even if the input image is half the maximum output size, since the compression ratio is fixed, only half of the memory is used for the code amount, and the remaining half is left. That is, the memory was not effectively used.

Further, the conventional fixed length processing in the block has the following problems. That is, the image data can be stored in the page memory by performing the fixed length processing in the block, but when data of an image size smaller than the original image size of the fixed length in the block is input, In spite of the fact that the image need not be compressed, the image is compressed more than necessary, and the image quality is degraded and the page memory cannot be used effectively.

For example, in an image coding apparatus having a page memory which has a capacity for an A3 image when a fixed length within a block is performed at a certain compression ratio, the A4 image data is coded by using the method shown in the conventional example. In this case, since the compression is performed at the same compression ratio, only half of the capacity of the page memory is eventually used, and the effective use of the page memory cannot be achieved.

[0015]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems, and has the following structure as one means for solving the above-mentioned problems. That is,
Output means for outputting image information formed from a plurality of images in one page, and storage having a storage capacity smaller than a storage capacity corresponding to a maximum output area that can be output by the output means and storing the image information Means, receiving means for receiving a plurality of image size information sent prior to the image information output by the output means, and calculating means for calculating the total image size by the input size information of each image, By changing the compression condition of each image information based on the total image size,
A compression means for performing a compression process, wherein the compression means
Image information storage means for storing the compressed image information in the storage means.

[0016]

[0017]

With the above arrangement, it is possible to provide a device which makes the most efficient use of the storage means provided in the device, and it is possible to provide an image which requires a small memory capacity even in a printer requiring a large capacity, especially in a color printer. A processing device can be provided.
In addition, when the fixed length is set in the block, the storage unit can be effectively used by changing the compression ratio according to the image size of the image data.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the accompanying drawings.

[0019]

FIG. 1 is a block diagram showing the configuration of a printer according to a first embodiment of the present invention. In FIG. 1, reference numeral 11 denotes an input terminal which is an input source of information connected to a printer. The information source connected to the input terminal 11 is a host computer, or a page description language which has been realized in recent years. For example, a formatter equipped with an interpreter.

Reference numeral 12 denotes an I / O of the printer, which controls an interface with a connected device connected to the input terminal 11, inputs information from the connected device, and receives information from the connected device.
3 and to the compression processing unit 14. Reference numeral 13 denotes a compression control unit which receives information on the image size from the I / O 12, sets a target compression ratio, and controls the compression processing in the compression processing unit 14.

Reference numeral 14 denotes a compression processing unit which inputs image information from the I / O 12 and reduces the redundancy of the image to perform encoding. Reference numeral 15 denotes a memory for storing a code from the compression processing unit 14. In the present embodiment, the storage capacity of the memory 15 is a memory having a smaller storage capacity than the storage capacity for storing the image information of the maximum output size in the printer engine 17.

Reference numeral 16 denotes a decompression processing unit, and a compression control unit 14
, The factors used for the control (for example, information such as the target compression rate and the amount of code assigned to each block) are received, and the code information coded by the compression processing unit 14 from the memory 15 is extracted based on the received factors. Decoding is performed in accordance with the convenience of the printer engine 17 (at the timing of the process speed of the engine).

A portion surrounded by a broken line in FIG. 1 described above corresponds to the printer in the present embodiment. In the present embodiment having the above configuration, an operation until image information is received from the input terminal 11 and stored in the memory 15 will be described.
This will be described below with reference to the flowchart of FIG.

In FIG. 2, step S1 is a step of inputting image size information, and the compression control unit 13 controls the I / O1.
2 means that this image size information is received prior to the image information to be output. At this time, for example, the image size received from the connected host computer is
For example, when the image area is rectangular, the type of <horizontal pixel number> and <vertical pixel number> may be used, and when the image area is a non-rectangular image area, the image may be received in the form of <area of image area>. Anyway, it is necessary to receive the information as header information before the image information.

Next, the compression control unit 13 executes the following step S
In step 2, a target compression ratio is set according to the previously input image size information. The target compression ratio in this case is to efficiently compress the image information of the input image size so as to fill the storage capacity of the memory 15 owned by the printer. Here, the capacity for the maximum image size of the printer of this embodiment is A, the capacity owned by the printer is B, and the capacity for the input image size is C.
In the above-described conventional example, since the compression ratio is fixed at A / B, the memory use ratio differs depending on the image size. Therefore, in the present embodiment, the target compression ratio is set to C / B.

Next, in step S3, the code amount for each block is set. Here, the image is blocked, and the image is compressed using orthogonal transformation or the like within the blocked block. Specifically, for example, if an input image is divided into X blocks by unblocking (not shown), a fixed length code for each block (B / X) is obtained according to a target compression ratio. Encoding. At this time, of course, the value of X is not fixed to the number of blocks for the maximum image size as in the conventional example, but changes depending on the input image size. For this reason, the code amount for (B / X) of each block also changes.

According to the determined code amount for each block, a quantization condition, for example, the number of quantization allocation bits for each component of the orthogonal transform coefficient in the block is selected. From the compression processing unit 14
Alternatively, it is transmitted to the decompression processing unit 16. Then, the process proceeds to step S4, where the compression processing unit 14 partially inputs the image information,
In the following step S5, the data is stored in the built-in buffer, and the flow advances to step S6. In step S6, the encoding according to the quantization condition set by the compression control unit 13 is advanced, and the encoded data encoded in step S7 is stored in the memory 15. Then, the process proceeds to step S8.

In step S8, it is determined whether or not encoding of all the images of the input size has been completed. If the encoding of all the images of the input size has not been completed, the process returns to step S4, and the processes of steps S4 to S7 are repeated. In this way, the image information for the input size is stored in the built-in memory of the printer, and the process ends when the encoding of all the images of the input size is completed.

In this way, the input image information can be encoded and compressed, processed, and stored in the memory 15 at the most efficient compression ratio in accordance with the memory capacity. When the encoded data stored in this manner is to be printed out from the printer engine 17 (at the time of decompression), the decompression processing unit 16 uses the information of the quantization condition from the compression control unit 13 to decompress. The coded data stored in the memory 15 is read out and decoded in synchronization with the process timing of the printer engine 17, and is sequentially sent to the printer engine 17 to output an image.

As described above, according to the present embodiment, even when the memory 15 having a small capacity is provided, the compression ratio can be freely changed according to the image size, and the provided memory 15 can be used to the maximum extent. Can be used effectively. As a result, unnecessarily large compression and the like are eliminated, image quality can be prevented from deteriorating, and printers, such as color printers, that generally require a large capacity memory only with a small storage capacity memory are manufactured. Can be

[0031]

[Second Embodiment] The above description has been made with reference to an example in which the input image information is, in principle, an image of a single specification. However, the present invention is not limited to the above-described example, and a case where an image output from the printer engine 17 has a plurality of images for one page of output paper is naturally included in the present invention.

Hereinafter, the image output from the printer is output paper 1
A second embodiment according to the present invention applied to a case where a plurality of images are provided for a page will be described. Also in the second embodiment, the basic configuration is the same as that of the first embodiment shown in FIG. 1 and can be configured only by a different processing procedure. The second embodiment is applied to a case where an image output from the printer engine 17 has a plurality of images for one page of output paper.

FIG. 3 shows an example of an image layout for one page of output paper to be input and processed in the second embodiment. In the figure, the area indicated by the broken line is the maximum image size that can be output by the printer engine 17. The area enclosed outside the maximum image size indicates the size of the output paper. In the example shown in FIG. 3, three types of image information of an image A, an image B, and an image C are laid out at a position shown in a page by a host computer or the like. Now, when it is desired to output such an image, in the second embodiment, encoding is performed as follows.

The encoding operation procedure according to the second embodiment of the present invention will be described below with reference to the flowchart of FIG. First, in steps S11 to S13, the compression control unit 13 performs each of the images A, B, and C before the respective image information from the host computer or the like of the connection destination in the same manner as in the first embodiment. The size information is sequentially received.
Each size information may be in the form of <the number of horizontal pixels> and <the number of vertical pixels> as shown in FIG. 27, for example.

Subsequently, the process proceeds to step S14, in which the sizes of all the input images are calculated. In this case, A + B +
C size. Since there are three types of input images, the total number of blocks to be blocked can be calculated from the total image area. Therefore, in the following step S15, all the block numbers are calculated and obtained. After the total number of blocks has been determined in this manner, the processing from the step S2 shown in FIG. 2 of the first embodiment described above can be applied as it is to the processing from encoding to storage in the memory. Therefore, detailed description of the following processing is omitted.

That is, irrespective of the number of images, by calculating the entire size of the input image before inputting the image information, it is possible to set an optimum encoding condition corresponding to the size. In order to realize the present embodiment, it is needless to say that image layout information, for example, the writing start positions of the images A, B, and C must be input.

[0037]

Third Embodiment FIG. 5 shows a third embodiment according to the present invention. FIG. 5 is a block diagram showing the configuration of the third embodiment according to the present invention. The third embodiment is an application of the first embodiment, and the same parts as those in FIG. 1 are denoted by the same reference numerals and different parts will be described. In FIG. 5, reference numeral 51 denotes a compression control unit, which controls compression conditions so as to perform optimal compression for the memory capacity of the memory 15 as in the embodiment of FIG. Reference numerals 52 and 53 denote switching circuits (switches).

The compression control unit 51 of the third embodiment has an I / O1
The information received from 2 is image size information. In the present embodiment, control is performed so that compression processing is not performed under certain conditions. FIG. 6 is a flowchart showing an operation procedure for switching the switch 52 in the third embodiment having the above configuration.

Hereinafter, the operation of the third embodiment according to the present invention will be described with reference to the flowchart of FIG. The compression controller 51 first inputs image size information in step S21. In the following description, it is assumed that the number of pixels of the input image size is P, for example. Subsequently, in step S22, the amount of information necessary for the input image is calculated. For example, assuming that the information amount is C and the number of gradation bits per pixel is D, the information amount C is calculated by the product of P and D. In the case of a color printer, the number D of gradation bits includes information on the input color space. For example, with information of 8 bits for each single color,
Now, when information is received in three color spaces of R (red), G (green), and B (blue), calculation is performed with D = 24 (bits). In this case, the information amount C is equal to the required capacity when no compression is performed.

Subsequently, in step S23, the information amount C is compared with the memory capacity (B) of the memory 15. If B is larger than C in terms of capacity, the process directly proceeds to step S25 without compression, and is stored in the memory 15. Conversely, if C needs more capacity than B, then go to step S24,
In step S24, encoding is performed by compression processing as in the first embodiment, and the flow advances to step S25. And step S
At 25, it is stored in the memory 15.

That is, the judgment in S23 is transmitted to the switch 52, and is sent to the memory 1 via the compression processing unit 14.
5 or directly in the memory 15. The switch 53 operates in the same manner as the switch 52. When the data is compressed and stored in the memory 15, the data is decoded by the decompression processing unit 16 and output to the printer engine 17. If the data is directly stored in the memory without being compressed, the data is directly read out from the memory 15 and
Output to

As described above. By separating the operation based on the image size information, efficient memory utilization can be realized.

[0043]

[Fourth Embodiment] FIG. 7 is a block diagram showing a main part of a fourth embodiment according to the present invention. In the fourth embodiment, the compression control method of the first embodiment is applied to variable-length coding, and the same parts as those in FIG. 1 are denoted by the same reference numerals and detailed description is omitted. In FIG. 7, reference numeral 71 denotes a compression control unit according to the fourth embodiment, which receives image size information from the I / O 12 and sets a target compression ratio as in the first embodiment. The compression process is performed based on the target compression ratio. Here, the fourth
In the embodiment, an example of adaptation to a compression method in which an orthogonal transform is performed while an image is blocked, the transform coefficient is subjected to a quantization process, and the quantized coefficient is subjected to endropy coding such as Huffman coding will be described.

The compression control section 71 sets conditions for compression based on information on the target compression ratio and the amount of code per block. In this case, since the bias of the redundancy is generated for each of the blocks, the amount of code generated when the quantized coefficient after the quantization is subjected to the end-ropy coding is naturally not constant. For this reason, the fourth embodiment is characterized in that the allocated code amount per block has a certain width or more.

The compression processing unit 72 receives information on the quantization condition selected based on the reference code amount per block from the compression control unit 71, quantizes the orthogonal transform coefficients, and performs endropy coding on the quantized coefficients. . The codes encoded by the compression processing section 72 in this manner are sequentially stored in the memory 15. As described above, in this embodiment, since each block is coded by variable length coding, the code amount stored in the memory 15 is not fixed. Therefore, in the fourth embodiment, the code amount counter 73 is connected to the memory 15 to detect the code amount stored in the memory 15.

The current code amount information is transmitted from the memory 15 to the code amount counter 72, and information on the ratio between the current region and the total image size is transmitted from the compression processing unit 72. The code amount counter 72 receives this and transmits it to the compression control unit 71. The compression control unit 71 estimates from the two types of information sent from the code amount counter 72 whether or not the data can be stored in the memory 15 even if the encoding is advanced under the same conditions. Then, the quantization condition is finely changed so that the encoding in the memory 15 can be completed.

The quantized condition after the change is also stored in the compression processing unit 72.
The compression processing unit 72 compresses the input image information according to the transmitted quantization condition. In the block where the quantization condition is switched, the switching information may be encoded, or several kinds of quantization tables may be stored in advance, and the index information of the table may be encoded.

In the case of the decompression processing, the decompression processing section 74 performs the decompression processing based on the information on the quantization condition such as the quantization table transmitted from the compression control section 71, and transmits it to the printer engine 17. As described above, even if the code amount is varied for each block, since the entire image size is transmitted in advance, it is possible to execute a so-called fixed length process in the image that fits in the memory.

As described above, according to the first to fourth embodiments, in a printer having a memory of a predetermined capacity, the compression ratio can be freely changed according to the image size. Can be used to the maximum possible extent. As a result, it is possible to commercialize a printer, for example, a color printer, which generally requires a large capacity only by providing a memory with a small storage capacity.

[0050]

Fifth Embodiment Next, a fifth embodiment according to the present invention will be described. FIG. 8 is a block diagram showing an embodiment in which the present invention is applied to an image coding apparatus. In the fifth embodiment shown in FIG. 8, image data and its image size are input and the input image is input. The compression ratio is changed according to the size, fixed length in the block is changed at the changed compression ratio, and then stored in the page memory.At the time of output, the data is extracted from the page memory and decompressed, and the image data is output from the output terminal. FIG. 9 is a block diagram showing a process up to output of.

In FIG. 8, image data is input from an input terminal 101, and is blocked into 8 × 8 by a block forming circuit 102. Further, orthogonal transformation is performed on a block basis.

Here, DCT (Discrete Cosine Transform)
form) The circuit 103 is used. This DCT circuit 103
, The image data is converted into DCT coefficients, and the quantization circuit 105 performs a quantization process described later. A packing circuit 107 sequentially assigns each component to a bit distribution selecting circuit 108.
The data is packed and output one-dimensionally with the bit length distributed by the bits. Then, the data arranged one-dimensionally is sequentially stored in the page memory 110. In this way, the fixed length processing within the block is performed in accordance with the bit distribution determined for each block, and the block is compressed and stored in the page memory.

When decompressing and outputting image data, the data is read from the page memory 110 and is read out from the page memory 110 as shown in FIG.
Processing reverse to that at the time of compression is performed by each processing circuit of the unpacking circuit 111, the inverse quantization circuit 112, the IDCT circuit 113, and the rasterization circuit 114, and the expanded data is output from the output terminal 115. Is done. With respect to the image data input from the input terminal 101, the image width and the image height (width, height) of the image data are input from an input terminal 104 which is another input terminal. The size of the image can be determined based on the image width and the image height of the image data. Therefore, for example, an image width of 8 w
When an image having an image height of 8h is input, if one block at the time of fixed length within a block is set to 8 × 8, this image is divided into w × h blocks.

Therefore, the number of bits that can be assigned to one block is M / (w × h) bits, and if the number of bits is fixed in block, the above-mentioned image data can be effectively used by effectively using the page memory. Can be stored. In the fifth embodiment, by paying attention to this point, the number of bits to be allocated to one block is calculated by inputting the image size as described above, and switching to the bit distribution according to the number of bits is performed to fix the block. Perform lengthening.

That is, the bit distribution selection circuit 108 calculates the number of bits to be allocated to one block from the image size (image width × image height) input from the input terminal 104, and prepares the number of bits according to the calculation result. A desired bit distribution is selected from a plurality of bit distribution tables. At the same time, a plurality of quantization tables are created from the plurality of bit distribution tables so as to satisfy the relationship as in the conventional example, and are selected by the bit distribution selection circuit 108 when actual image data is input. The quantization table 106 is switched according to the bit distribution.

In the following, the bit distribution table 10 will be described in a simple manner, in which one block is in units of 4 × 4 pixels, and the bit precision of the DCT coefficient output from the DCT circuit 103 is 8 bits.
9 and how the quantization table 106 is selected will be described. Assuming that the image size of a certain image A is 4w × 4h, the value of the image width × the image height is input to the bit distribution selecting circuit 8, and the number of bits per block is calculated. Now, assuming that the capacity of the page memory is 50 wh bits, the number of bits per block is 50 bits.

One bit distribution is selected from the plurality of bit distribution tables 109 based on the number of bits. As an example of the bit distribution, a distribution as shown in FIG. 9 can be considered. This distribution method is a well-known technique as a bit distribution method utilizing the characteristics of the DCT coefficient, and will not be particularly described. The quantization table corresponding to the bit distribution is as shown in FIG. 10 using the relation in the conventional example. This quantization table has a plurality of quantization tables 1 in advance.
06 when the actual image is compressed.
It is selected according to the number of bits per block and is input to the quantization circuit 105.

On the other hand, when another image B is input and its image size is 2w × 2h, the number of bits per block is 1 which is twice the number of bits when the image A is input.
00 bits. FIG. 11 shows an example of bit distribution according to the number of bits. Accordingly, the bit distribution selecting circuit 108 switches the bit distribution of FIG. 9 to the bit distribution of FIG. Similarly, switching from the quantization table of FIG. 10 to the quantization table of FIG. 12 is performed.

As described above, according to this embodiment, the image size is input together with the input image data, and the bit allocation and quantization table are switched according to the image size, and the number of bits allocated to one block is changed. Thus, the fixed length processing in the block can be performed by effectively using the page memory.

[0060]

Sixth Embodiment FIG. 13 shows a sixth embodiment according to the present invention. 13, the same components as those of the fifth embodiment shown in FIG. 8 described above are denoted by the same reference numerals, and detailed description will be omitted.
In FIG. 13, the image size is input from the input terminal 104 to the bit number calculation circuit 123 according to the image data input from the input terminal 101. The bit number calculation circuit 123 calculates the number of bits allocated to one block and outputs the result. Specifically, when the capacity of the page memory is M and the configuration of one block is n × n pixels, M
/ (N ² ) is calculated and the value is output to the bit distribution generating circuit 24. In the bit allocation component circuit, bits are allocated to each component of the n × n blocks so that the total number of bits of one block becomes the number of input bits. The method of assigning each component is a well-known technique and will not be described here.
Further, in the quantization table generation circuit 22, the bit allocation is input from the bit allocation generation circuit 24, and when the bit precision of the DCT component is C and the bit allocation is B _ij as in the conventional example, 2 ^{(C-Bij )} Is calculated for each component in the block, and the result is output to the quantization circuit 5.

As described above, according to the sixth embodiment, the bit distribution table and the quantization table can be omitted, and the hardware configuration can be simplified.

[0062]

Seventh Embodiment FIG. 14 shows a seventh embodiment according to the present invention. In the conventional example, when the fixed length in the block is performed, compression is performed regardless of the size of the input image. However, depending on the image size, there is a case where the image data can be stored in the page memory without being compressed. When data passes through the compression processing unit, an error always occurs in the orthogonal transformation unit, no matter how low the compression ratio is set.

Therefore, in the seventh embodiment, a process that does not perform compression processing is provided as shown in FIG. Here, the fixed length compression section 34 in the block and the fixed length extension section 36 in the block.
Corresponds to the portion surrounded by the broken line and the alternate long and short dash line in FIG. 8 of the fifth embodiment. Image data is input from the input terminal 30, and at the same time, an image size is input from the input terminal 31. The compression determination circuit 33 compares the total information amount of the input image with the capacity of the page memory based on the image size, and when the total information amount of the input image is smaller, the compression determination signal 33 Outputs a low level. Conversely, when the total information amount of the input image is larger, the compression determination signal 38 is output as a High level.

The compression determination signal 38 is input to the selector 32. When the signal value is High, the process of performing fixed-length compression in the block and then input to the page memory 35 is selected. When the signal value is Low, the compression process is performed. , The process directly input to the page memory 35 is selected. In this manner, the image data input from the input terminal 30 is transferred to each selected process and stored in the page memory 35.

When outputting image data, the stored data is read from the page memory 35 and sent to the selector 39. At this time, a compression determination signal 38 is input to the selector 39 from the compression determination circuit 33. The selector 39 selects a process in which the fixed length expansion in the block is performed when the compression determination signal 38 is at the High level, and selects a process which is output without performing the expansion process when the compression determination signal 38 is at the Low level. After the data has passed through each process, image data is output from the output terminal 37.

As described above, according to the seventh embodiment,
It is determined whether or not to perform compression processing according to the image size. For an image that does not need to be compressed, another path that does not pass compression processing from the beginning is provided. As a result, image encoding can be performed in a form in which the input data is completely preserved without generating a conversion error or the like due to the compression processing.

[0067]

Eighth Embodiment FIG. 15 shows an eighth embodiment according to the present invention.
Shown in In a color image compression system usually composed of RGB data, color conversion is performed on image data before performing compression processing in order to increase the compression ratio. Specifically, the RGB data is converted to YUV data, and compression can be performed using a relatively large compression ratio for the UV data while keeping the image quality sufficiently.

Further, in view of human visual characteristics at that time, even if UV data is thinned out, deterioration in image quality is not conspicuous, and therefore, for example, 1/2 thinning out in the horizontal direction is performed.
Compression processing is performed after halving the data amount of. However, no matter what image is input at this time, the decimation process is performed, and then compression by fixed length within the block is also performed. Processing will be performed.

Therefore, in the eighth embodiment, whether or not to perform thinning is determined based on the image size input together with the image data, and no thinning is performed for an image having a small image size. . In FIG. 15, color image data composed of RGB data is input from an input terminal 51, and at the same time, an image size is input from an input terminal 52. Based on the input image size, the image size input by the thinning-out determination circuit 43 is compared with a predetermined threshold T, and if the value of T is larger than the input image size, a thinning process is performed. In order to prevent this, the thinning-out determination signal 53 is output at a low level.

Conversely, when the value of T is smaller than the input image size, the thinning-out determination signal 53 is output as a high level in order to perform the thinning-out processing.
The above-described threshold value T is set in the thinning-out determination circuit 43 as an image size that does not need to be thinned out in consideration of the conditions under which the image encoding apparatus of the present embodiment is used. The thinning-out determination signal 53 is input to the selector 42. The selector 42 selects a process in which the thinning is performed when the value of the thinning determination signal 53 is High, and selects a process in which the output is directly performed without performing the thinning when the value of the thinning determination signal 53 is Low. The data converted from RGB to YUV by the color conversion circuit 41 is transferred to the process selected by the selector 42. When the thinning process is performed, the thinning circuit 44 thins out the UV data in the horizontal direction or the vertical direction. The image data subjected to the thinning processing or the image data sent as it is without performing the thinning processing is input to the in-block fixed length compression unit 45 similar to that of the above-described fifth embodiment, and compression processing is performed. . afterwards,
It is stored in the page memory 46.

On the other hand, at the time of decompression, the decompression process is performed by the in-block fixed decompression unit 47 similar to that of the fifth embodiment, and the decompressed data is output to the selector 48. Here, the thinning-out determination signal 5 is supplied to the selector 48 similarly to the compression.
3 is input and when the thinning-out determination signal 53 is High, a process for performing interpolation is selected.
When 3 is Low, a process for outputting as it is is selected.

When the interpolation processing is performed, the pre-interpolation is performed in the same direction (horizontal or vertical) as when thinning out the UV data. Further, the data subjected to the interpolation processing or the data sent as it is without performing the storage processing is input to the color conversion circuit 50, where the YUV data is converted into the RGB data. Data output is performed.

As described above, according to the eighth embodiment,
It is determined whether or not to perform the thinning-out processing according to the image size. The thinning-out processing is not performed for an image whose image size is not very large. As described above, according to the fifth to eighth embodiments, by referring to the image size of the input image and changing the compression ratio according to the image size, the image of any size is input. However, the fixed length in the block can be increased with an optimum compression ratio. Thus, the image data can be stored by effectively using the page memory, and the image can be encoded without performing the compression processing more than necessary and deteriorating the image quality.

[0074]

Ninth Embodiment FIG. 16 shows a ninth embodiment according to the present invention in which the present invention is applied to a printer which is an image output device.
In FIG. 16, reference numeral 200 denotes a printer according to the ninth embodiment of the present invention, and reference numeral 210 denotes a host that outputs print information such as image information to be printed out by the printer 200 of the present embodiment.

In the printer 200, reference numeral 201 denotes a host I / F, which controls an interface with the host 210. Image information to be printed generated by the host 200 is received by the host I / F 201 and is changed by the variable compressor 202.
Sent to The variable compressor 202 performs a predetermined compression process on the received image information and stores it in the page memory 203.
When storage of one page of images is completed by sequentially performing compression processing, the original image information is decoded by the variable decompressor 204, sent to the print engine 206 via the engine I / F 205, and stored in a recording paper or the like. Is printed out.

Here, as an example, an image for one page is described as being composed of three images of partial images A, B and C as shown in FIG. 27 described above.
Conventionally, a single two-dimensional image, which is a D image including images A, B, and C, is stored in a page memory. On the other hand, in the ninth embodiment, the three partial images A, B, and C are independently managed, and each of the partial images is stored one-dimensionally in the page memory 203. Each image has an absolute position (x _i , y _i ) (i =
1, 2,...), The area width W _i , and the area height H _i , and are defined by the header of the image data file.

FIG. 17 shows an example of the configuration of the header used in the ninth embodiment. In FIG. 17, frames 1,
Since the absolute positions x ₁ and y ₁ of the partial image A are stored in 2 (F1, F2), they are separated by the host I / F 201 and sent to the memory management unit 208. Since the width W ₁ and the height H ₁ of the partial image A area are stored in subsequent F3 and F4, they are separated by the host I / F 201 and sent to the memory allocation control unit 207.

FIG. 18 is a detailed block diagram of the memory allocation control unit 207. The information of, for example, the width W ₁ and the height H ₁ input to the memory allocation control unit 207 is
1 and are stored in the respective registers of the W register file 213 and the H register file 214 specified by the register address section 212. This operation is performed for all images.

As described above, the image data is stored in the host I / F.
The data is separated at 201 and sent to the variable compression section 202. Therefore, in order to obtain the image information amount H, the calculation unit 215 performs the calculation given by the following equation (1). Assuming that the memory amounts allocated to the respective partial images are respectively Ma, Mb, and Mc, the following equations (2) to (2) are used.
Given by (4).

Ma = Mp ｛(W ₁ × H ₁ ) / H｝ (2) Mb = Mp ｛(W ₂ × H ₂ ) / H｝ (3) Mc = Mp ｛(W ₃ × H ₃ ) / H ｝ (4) Here, Mp is the total capacity of the page memory 203. FIG. 19 shows an example of this memory allocation.

The compression ratios Na, Nb, Nc are given by the following equation (5). Na = Nb = Nc = (Ma) / (W ₁ × H ₁ ) = Mp / H (5) This operation is performed by the compression ratio determining unit 216, and the result is sent to the variable compressor 202 and the variable decompressor 204. Operation is determined. The setting for each partial image is completed in the frame 12, and the image data starts from the frame 13. Each image data is compressed under the conditions set above, and is recorded at the address of the page memory 203 specified by the memory management unit 208.

The image data for one page is stored in the page memory 2.
After recording in 03, the print engine 206 is started. At the time of printing, the address of each pixel is output from the engine I / F unit 205. For this reason, the memory management unit 208
Obtains a physical address on the page memory 203 corresponding to the address, reads out the pixel information,
The print job is sent to the print engine 206 via the F unit 205. The print engine 206 forms an image while performing a scanning operation. This operation is repeated over one page, and the printing is completed.

Although the description so far has been made for the case of three images, other cases can be processed in the same procedure. As described above, according to the ninth embodiment, since page image information composed of a plurality of images can be compression-managed for each image, a printer device capable of high-quality printing can be realized at low cost. it can.

[0084]

Tenth Embodiment In the ninth embodiment described above, the compression ratio of each partial image is controlled to be equal. However, the required image quality may differ depending on the picture of each partial image.
In the tenth embodiment, it is configured such that relative area information required for each image can be input. In the tenth embodiment, the schematic configuration of the printer is the same as that of the ninth embodiment shown in FIG. 16, but in the tenth embodiment, the configuration of the memory allocation control unit 207 is partially different. The control information of the image data sent from the host 210 via the host I / F 201 is partially different, and the host 210 sends the relative area information required for each image in addition to the information of the ninth embodiment.

FIG. 20 shows a detailed configuration of the memory allocation control unit of the tenth embodiment according to the present invention. 20, the same components as those in FIG. 18 described above are denoted by the same reference numerals, and detailed description is omitted. In the tenth embodiment, an area level register file 220 is provided in the memory allocation control unit 208 as shown in FIG.
Via 201, the relative area information required for each image is
The input terminal f shown in FIG. 20 is configured to be separately input.

For example, in the case where A image> B image = C image, the equation (1) for calculating the image information amount H in the ninth embodiment in the arithmetic unit 215 is modified as follows to obtain the first image.
The image information amount H 'in the embodiment of 0 is obtained. H '= (W ₁ + H ₁ ) (1 + k ₁ ) + W ₂ × H ₂ + W ₃ × H ₃ (6) where k ₁ ; a specified value. Is increased by (1 + k ₁ ) times, and the ratio in the page memory 203 increases. Therefore, assuming that the amount of memory allocated to each image is Ma ', Mb', Mc ', Ma', Mb ', Mc' are expressed by the following equations (7) to (9).
Is required.

Ma ′ = Mp [{W ₁ × H ₁ (1 + k ₁ )} / H ′] (7) Mb ′ = Mp {(W ₂ × H ₂ ) / H ′} (8) Mc ′ = Mp} (W ₃ × H ₃ ) / H ′｝ (9) The subsequent processing is the same as in the ninth embodiment described above.

As described above, according to the tenth embodiment, not only the page image information composed of a plurality of images can be compression-managed for each image, but also the relative area required for each image. Because we ’ve configured it so you can enter information,
Further, a printer device capable of printing a high-quality hard copy can be realized at a low price.

[0089]

[Eleventh Embodiment] FIG. 21 shows an eleventh embodiment according to the present invention. In the eleventh embodiment, the same components as those in FIGS. 16 and 20 in the above-described tenth embodiment are denoted by the same reference numerals, and detailed description will be omitted. In the eleventh embodiment, the detailed configuration of the memory allocation control unit 207 in the ninth and tenth embodiments described above is shown along with other configurations. In the eleventh embodiment, the switching unit 211 has the function of the host I / F 201 as well.

In the eleventh embodiment, each of the images A, B, and C sent from the host 210 and managed independently as shown in FIG. The image data is calculated based on the absolute position (x
_i , y _i ) (i = 1, 2,...), the width of the image area W _i , and its height H _i , as well as the attributes of the image, for example, the attribute A _i in the case of image A, the header of the image data file. Defined in the section. For this reason, an attribute discriminator 230 for discriminating image attributes is provided.

FIG. 22 shows an example of the header of the image data file in the eleventh embodiment. The attribute A _i of the image shown in F5 means its source, for example, CG, scanned image, TV camera, VTR.
In the embodiment, mapping is performed by using a code. The origin position (x ₁ , y ₁ ) of the A image is defined as the width and height W ₁ , H ₁ of the image area in frames F 1, F 2 as F 3, F 4, and the attribute thereof as F 5. The B and C images are similarly defined by F6 to F15, and the image data after F16 is image data. Configurations other than these attributes are the same as those in FIG. 17 described above.

The header of the image data file from the host 210 is separated by the switching unit 211. (X ₁ , y
₁₎ The memory management unit _{208, (w i, H i} ) the W register file 21 designated by the register address 212
3. Stored in the H register file 214. Also, A
_i is sent to the attribute discriminating section 230, where it is discriminated and stored in the image quality level register file 220, respectively. The image data is sent to the variable compression section 202.

Next, a calculation is performed in which the calculation unit 215 for obtaining the total image information amount H in the eleventh embodiment is given by Expression (11). k _i ; a correction term given from the image quality level register file 220.

Assuming that the memory amounts allocated to the respective partial images are Ma, Mb, and Mc, respectively, they are given by the following equations (12) to (14). Ma = Mp ｛(W ₁ × H ₁ ) / H｝ (1 + k ₁ ) (12) Mb = Mp ｛(W ₂ × H ₂ ) / H｝ (1 + k ₂ ) (13) Mc = Mp ｛(W ₃ × H ₃ ) / H｝ (1 + k ₃ ) (14) Here, Mp is the total capacity of the page memory 203.

K _i is the image quality level register file 220
Is a correction term given by This correction term is an attribute discrimination unit 230 | k _i | <is determined to a value of one. For example, A
Assuming that the image is a computer graphic (CG), the B image is an image from a scanner, and the C image is an image from a TV camera, the bandwidth is A>B> C. Assuming that the compression ratio for each image is Na, Nb, and Nc, respectively, [Na>Nb> Nc]
It is necessary to

Here, from the equations (12), (13) and (14), Na = Ma / (W ₁ × H ₁ ) = (Mp / H) (1 + k ₂ ) (15) Nb = (Mp / H) (1 + k ₂ ) (16) Nc = (Mp / H) (1 + k ₃ ) (17) Calculations of the equations (15), (16) and (17) are performed by the compression ratio determination unit 216, and the result is variable compression. And a variable decompressor 204. Image data compressed at this compression ratio by the variable compressor 202 is stored in a page memory 203.
Is accumulated in

Therefore, the correction term k _i is [k ₁ > k ₂ > k ₃ ]
The constant mapping is performed so that After the image for one page is stored in the page memory 203 in this way, the printing process starts. Since the print engine 206 of this embodiment performs main scanning and sub-scanning, the positions of the pixels to be printed are given from the engine I / F 205 as coordinate positions (x _p , y _p ) on paper. Memory address corresponding to this position, the memory management unit _{208 (x i, y i)} , (w i, H i), Ma, Mb, is determined from Mc. Pixel information is read from the page memory 203 according to the memory address, expanded by the variable expander 204 using the same parameters as when compressed by the variable compressor 202, and sent to the print engine 206 via the engine I / F 205. send.

In the above description, the case where there are three partial images has been described, but the same applies to other numbers of images.
As described above, according to the eleventh embodiment, when a page image composed of a plurality of partial images to which attribute information has been added is compressed and written to the page memory, an optimal Compressed parameters can be set automatically.

[0099]

Twelfth Embodiment FIG. 23 shows the structure of a twelfth embodiment. 23, the same components as those in the eleventh embodiment shown in FIG. 21 described above are denoted by the same reference numerals, and detailed description will be omitted. showed that. In the eleventh embodiment, the attribute of each partial image is added by the user on the host 210 to generate the image file shown in FIG. 22, but errors are likely to occur. Therefore, in the twelfth embodiment, the input device 24 for generating each partial image
1,242, etc. (for example, scanner, TV camera, VTR
..) Automatically adds attribute information and sends it to the host 210.

FIG. 24 shows the data structure. In FIG. 24, attribute information such as A ₁ ,
Put A _2, attach the image data to then F2 or later. The host 210 edits the partial image information to have the data configuration shown in FIG. Thus, it is possible to prevent an error in specifying the attribute of the image. The present invention may be applied to a system including a plurality of devices or to an apparatus including a single device.

It is needless to say that the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus.

[0102]

As described above, according to the present invention, in a printer having storage means of a predetermined capacity, the compression ratio can be freely changed according to the image size, and the storage means provided can be maximized. Can be used effectively. As a result, it is possible to commercialize a printer that generally requires a large capacity, for example, a color printer or the like, only by providing a storage means with a small storage capacity.

Also, by referring to the image size of the input image and changing the compression ratio according to the image size, the fixed length in the block is maintained at the optimum compression ratio regardless of the size of the input image. Can be done. For this reason, the image data can be stored by effectively using the storage means, and the image encoding can be performed without performing the compression processing more than necessary and deteriorating the image quality.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention.

FIG. 2 is a flowchart illustrating a main operation procedure according to the first embodiment of the present invention.

FIG. 3 is an example of an image layout used in a second embodiment according to the present invention.

FIG. 4 is a flowchart illustrating a main operation procedure according to a second embodiment.

FIG. 5 is a block diagram showing a configuration of a third embodiment according to the present invention.

FIG. 6 is a flowchart illustrating a main operation procedure according to a third embodiment.

FIG. 7 is a block diagram showing a configuration of a fourth embodiment according to the present invention.

FIG. 8 is a block diagram showing an image coding apparatus according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing an example of bit distribution in a fifth embodiment.

FIG. 10 is a diagram showing an example of bit distribution in a fifth embodiment.

FIG. 11 is a diagram illustrating an example of a quantization table according to the fifth embodiment.

FIG. 12 is a diagram illustrating an example of a quantization table according to the fifth embodiment.

FIG. 13 is a block diagram showing an image coding apparatus according to a sixth embodiment of the present invention.

FIG. 14 is a block diagram showing an image encoding apparatus according to a seventh embodiment of the present invention.

FIG. 15 is a block diagram showing an image encoding apparatus according to an eighth embodiment of the present invention.

FIG. 16 is a block diagram showing the configuration of a ninth embodiment according to the present invention.

FIG. 17 is a diagram showing a data configuration used in the ninth embodiment.

FIG. 18 is a block diagram showing a detailed configuration of a memory allocation control unit according to a ninth embodiment.

FIG. 19 is a diagram illustrating an example of allocating memory addresses to page memories according to the ninth embodiment.

FIG. 20 is a block diagram showing a detailed configuration of a memory allocation control unit of a tenth embodiment according to the present invention.

FIG. 21 is a block diagram showing the configuration of an eleventh embodiment according to the present invention.

FIG. 22 is a diagram showing a data configuration in the eleventh embodiment.

FIG. 23 is a block diagram showing the configuration of a twelfth embodiment according to the present invention.

FIG. 24 is a diagram showing a data configuration from an input device in a twelfth embodiment.

FIG. 25 is a block diagram showing a configuration of a printer according to a conventional technique.

And FIG. 26 is a block diagram showing a configuration of another printer according to the related art.

FIG. 27 is a diagram illustrating an example of a one-page image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Input terminal 12 Printer I / O 13, 51, 71 Compression control part 14 Compression processing part 15 Memory 16 Decompression processing part 17 Printer engine 31, 52, 104 Image size input terminal 33 Compression judgment circuit 43 Thinning out judgment circuit 44 Thinning out circuit 49 Interpolation circuit 52,53 Switch 72 Code amount counter 108 Bit distribution selection circuit 109 Bit distribution table 122 Quantization table generation circuit 123 Bit number operation circuit 124 Bit distribution generation circuit 200 Printer 201 Host I / F 202 Variable compressor 203 Page memory 204 Variable expander 205 Engine I / F 206 Print engine 207 Memory allocation control unit 208 Memory management unit 210 Host 211 Switching unit 212 Register address unit 213 W register file 214 H Sutafuairu 215 arithmetic unit 216 compression ratio determination unit 220 image quality level register file 230 attribute discriminating portion 241, 241 the input device

Continuation of the front page (72) Inventor Yuji Konno 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-87460 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) H04N 1/41-1/419 B41J 2/485 B41J 21/00 H04N 1/21

Claims (7)

(57) [Claims] An output unit for outputting image information formed from a plurality of images in one page; and a storage capacity smaller than a storage capacity corresponding to a maximum output area that can be output by the output means. Storage means for storing information; receiving means for receiving a plurality of pieces of image size information transmitted prior to the image information output by the output means; and calculating the total image size based on the input size information of each image. Calculating means for performing a compression process by changing a compression condition of each image information based on the total image size.
An image processing apparatus comprising: image information storage means for storing image information compressed by a stage in the storage means. 2. An image processing apparatus according to claim 1, wherein the compression condition of the image information by said compression means is a quantization condition of an orthogonal transform coefficient. 3. The image processing apparatus according to claim 1, wherein said image information storage means switches between execution and non-execution of compression processing by said compression means according to said image size information. 4. The compressing means includes a dividing means for dividing an image into blocks of a predetermined size, a transforming means for performing an orthogonal transformation on a block basis divided by the dividing means, and a dividing means on a block basis divided by the block means. 4. The image processing apparatus according to claim 3, further comprising a quantization unit that performs quantization. 5. The quantization unit according to claim 1, wherein each of the components of the block divided by the division unit is quantized with a different quantization coefficient, and the amount of information generated for each block is kept constant. Item 5. The image processing device according to Item 4 . 6. The compression means determines a code length to be allocated to each component of the block from a code amount allocated to each block by the division means for dividing the image into blocks of a predetermined size. 4. The image processing apparatus according to claim 3, wherein each of the components is controlled to have the code length. Wherein said compression means, by obtaining the code amount to be allocated to each block divided by the dividing means, the image size information inputted by the storage capacity of the storage means and input means, the compression ratio of the entire image information The image processing apparatus according to claim 6, wherein the image processing apparatus changes the setting.