JP4682662B2 - Image processing apparatus and image processing program - Google Patents

Description

  The present invention relates to an image processing apparatus and an image processing program, and more particularly, to an image processing apparatus and an image processing program that develop an image in a band buffer.

  An image forming apparatus such as a printer includes an image processing apparatus that performs image processing on print data, and a print engine that forms a desired image based on image data generated by the image processing apparatus. The image processing apparatus inputs print data described in a page description language (PDL) from a host computer, and converts the print data into an intermediate code that can be easily developed into bitmap image data. Then, the image processing device expands the bitmap image data from the intermediate code in the band buffer, performs color conversion and compression processing as necessary, and finally performs necessary processing such as binarization. The image data is output as an image reproduction signal to the print engine.

  Bitmap image data is RGB multi-gradation data corresponding to pixels, and a large-capacity memory is required to develop data for one print plane. Therefore, one print plane (unit that can be simultaneously printed by the print engine in one printing process) is divided into a plurality of band areas, and each band is developed from an intermediate code into bitmap image data. In other words, when all the data for one page is processed, a large-capacity memory area is required. Therefore, development from intermediate code to RGB bitmap image data or CMYK image data in units of subdivided band areas. Perform color conversion and compression.

  FIG. 1 is a diagram for explaining a band region. An image in one print plane 1 is composed of a character “A” 2, a rectangular figure 4, and a frog image 6. When the image for one print plane is divided into six band areas BND0 to BND5, the character 2, the rectangular figure 4, and the image 6 are located in the band areas BND0 to BND3 and do not exist in the band areas BND4 and BND5. .

Therefore, a conventional image processing apparatus generates an intermediate code for each band area from PDL print data for one print plane, and performs development, color conversion, and compression of bitmap image data from the intermediate code in band area units. . Then, the image processing apparatus decompresses and binarizes the compressed image data when the compressed image data for one print plane is ready or when a part of the image data is ready. The image reproduction signal is output to the print engine. A print system that generates an intermediate code in band units and develops bitmap image data as described above is described in Patent Document 1 below.
Japanese Patent Laid-Open No. 10-40031

  FIG. 2 is a diagram illustrating the problem of the image processing apparatus. In the case of developing bitmap image data in band units for the band areas BND1 and BND2 in FIG. 1, in the conventional image processing apparatus, the band width Wb is all fixed to the print plane width Wp. That is, when developing bitmap image data in band units, the image processing apparatus secures a band memory area having a capacity corresponding to the print plane width Wp in the internal memory area, and the bitmap image data generated from the intermediate code is stored in the band memory. Expand into the region. In this expansion to the band memory area, all the pixels in the band memory area are initialized with image data corresponding to the initial value “white” (specifically, white data is written), and RGB pixels are added to the pixels where the image exists. This is performed by developing bitmap image data (specifically, writing image data).

  In this case, in the case of the band area BND1, both end areas E1 and E2 other than the area where the character 2-2, the rectangle 4-1 and the image 6-2 are located remain at the initial values, and the generated bitmap image data Is never written. Also in the band area BND2, both end areas E3 and E4 other than the area where the rectangle 4-2 and the image 6-3 are located remain at the initial values.

  The subsequent color conversion processing from RGB to CMYK and the compression processing of the converted CMYK data are performed on the data of all the pixels including both end regions E1 to E4 in the band memory region.

  However, both end areas E1 to E4 are actually the same area as the color of the printing paper, and are areas in which no developer needs to adhere to the printing paper in the image forming apparatus, and the initial values are the image data as they are. Only. However, in the conventional example, the band memory area is always secured by the print plane width Wp, and initialization, color conversion, and compression processing are performed for all the band memory areas. Is wasted, and initialization, color conversion, and compression processing are wasted.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image processing apparatus and an image processing program that can omit processing to useless band memory areas.

  In order to achieve the above object, according to the first aspect of the present invention, bitmap image data is developed for each band area obtained by dividing a print plane into a plurality of areas based on an intermediate code converted from the print data. In the image processing apparatus, an image data existence area in which the bitmap image data in the band area exists is obtained from the intermediate code, and the bitmap image data is developed in a band memory area having a width corresponding to the image data existence area. The image reproduction signal generated from the developed bitmap image data is output to the print engine.

  According to the first aspect, the capacity of the band memory for developing the bitmap image data is limited to the bandwidth corresponding to the image data existence area, and the bitmap image data converted from the intermediate code is stored in the band memory area. expand. This bandwidth can be reduced if the image data existence area in the band area is narrower than the print plane width, reducing unnecessary initialization processing and reducing the processing man-hours required for development. Can be reduced. Also, since the image data existence area is different for each band area, and the capacity of the band memory area is different accordingly, image processing including development of bitmap image data is performed for the minimum capacity. The load can be reduced.

  In the first aspect, according to a preferred embodiment, the image processing apparatus further color-converts the bitmap image data expanded in the band memory area from the first color space to the second color space. Either or both of the color conversion process and the compression process for compressing the bitmap image data subjected to the color conversion are performed. Since the band memory area is limited to the width required to expand the bitmap image data except for both end areas where the bitmap image data is not expanded, in addition to the bitmap image data expansion process, the color conversion process performed thereafter In addition, the amount of data to be subjected to compression processing can be reduced, and the burden required for image processing can be reduced.

  In the first aspect, according to a more preferred embodiment, the image processing apparatus transmits an image reproduction signal generated from the bitmap image data in the band memory area to the image data existing area in the print plane. Output to the print engine according to the position. Accordingly, the print engine can form an image in the image data existence area in the print medium based on the image reproduction signal output from the image processing apparatus in accordance with the position of the image data existence area in the print plane. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

  FIG. 3 is a schematic configuration diagram of the image processing apparatus according to the present embodiment. In FIG. 3A, print data PDL in page description language is supplied from the host computer HOST to the controller 12 of the printer 10 which is an example of an image forming apparatus. The controller 12 converts the print data PDL into an intermediate code, expands bitmap image data from the intermediate code in the band memory area B-BUF, and prints an image reproduction signal 16 generated from the expanded bitmap image data. 24. In this case, the controller 12 corresponds to the image processing apparatus.

  In FIG. 3B, the printer driver P-DR in the host computer HOST generates an intermediate code IC for each band area from the print data PDL, and supplies the intermediate code IC to the controller 12 of the printer 10. The controller 12 expands the bitmap image data into the band memory area B-BUF based on the supplied intermediate code IC, and supplies the image reproduction signal 16 generated from the expanded bitmap image data to the print engine 24. Also in this case, the controller 12 corresponds to the image processing apparatus.

  Further, in FIG. 3C, the printer driver P-DR in the host computer HOST generates an intermediate code for each band area from the print data, and the bitmap image data is converted into the band memory area B- based on the intermediate code. The data is expanded into a BUF, color-converted and compressed as necessary, and the compressed bitmap image data BM is output to the controller 12 in the printer 10. The controller 12 performs color conversion and binarization processing as necessary, and outputs an image reproduction signal 16 to the print engine 24. In this case, a printer driver P-DR that is a program corresponds to the image processing apparatus.

  As described above, the image processing apparatus according to the present embodiment corresponds to at least a portion in which bitmap image data is expanded in the band memory area from the intermediate code, and the band memory area to be subjected to image processing in units of bands, The band area is limited to an area where bitmap image data exists.

  FIG. 4 is a configuration diagram of the printer in the present embodiment. The printer 10 in FIG. 4 corresponds to the printer 10 in FIG. The printer 10 includes a controller 12 corresponding to the image processing apparatus and a print engine 24. The controller 12 includes an interface IF that receives print data PDL in the print control language from the host computer, a central processing unit CPU that converts the print data PDL into an intermediate code IC for each band area, and bitmap image data based on the intermediate code. A color conversion unit 18 that performs color conversion from RGB to CMYK, a compression unit 20 that compresses bitmap image data, a binarization unit 22 that binarizes bitmap image data, An image reproduction signal 16 generated by the pulse modulation unit is supplied to the print engine 24. The pulse modulation unit PWM converts the binarized data into a pulse signal that is an image reproduction signal. Further, the controller 12 has a memory unit 14, and the memory unit 14 includes an intermediate code buffer IC-BUF for storing intermediate codes, and a band memory area (hereinafter referred to as band buffer) B for storing bitmap image data. -BUF is secured.

  When the printer 10 in FIG. 4 corresponds to the printer 10 in FIG. 3B, the interface IF of the controller 12 receives the intermediate code IC from the host computer and stores it in the intermediate code buffer IC-BUF. Then, the controller 12 expands the bitmap image data in the band memory area B-BUF based on the intermediate code by the expansion unit 16.

  When the printer 10 in FIG. 4 corresponds to the printer 10 in FIG. 3C, the controller 12 is not provided with the expansion unit 16, the color conversion unit 18, the compression unit 20, and the like, and the received bitmap image It only binarizes the data and outputs the image reproduction signal 16 to the print engine.

  FIG. 5 is a flowchart of the printing procedure in the present embodiment. FIG. 6 is a diagram illustrating a configuration example of the memory unit. Although the printing procedure of FIG. 5 can be applied to any type of FIG. 3, as an example, the printing procedure will be described based on the case where it is applied to FIG.

  Print data in the PDL format is generated by the host computer (S10) and supplied to the controller 12 of the printer. The controller 12 converts the print data into an intermediate code for each band area (S12). At this time, as shown in FIG. 6, the controller 12 secures a pointer string area PL corresponding to the band area and an intermediate code buffer IC-BUF in the memory unit 14, and NULL as an initial value in the pointer string area PL. Write the code.

  The central processing unit CPU of the controller 12 interprets the print data, detects what character, figure, and image should be printed in which area in the print plane, and prints the character, figure, Generate intermediate code corresponding to the image. Then, the intermediate code is written into the intermediate code buffer IC-BUF. At that time, as shown in FIG. 6, the addresses ADD1 to ADD4 in the intermediate code buffer IC-BUF are written in the pointer string area PL corresponding to the band area of the generated intermediate code.

  In the case of the image shown in FIG. 1, since intermediate codes are generated in the band areas BND1 to BND3, the addresses ADD1 to ADD4 are written in the areas corresponding to the band areas BND1 to BND1 of the pointer sequence PL, and the other bands. The area corresponding to the area remains a NULL code. Therefore, by referring to this pointer row PL, it is possible to identify whether or not an intermediate code exists in each band area, and a buffer in which the intermediate code of the band area where the image to be formed exists is stored. The address in the IC-BUF can be acquired.

  PDL format print data is usually divided for each print plane (or page), and the print data in that print plane is interpreted and converted into intermediate code to support graphics in one print page All intermediate codes are stored in the intermediate code buffer IC-BUF.

  Next, the controller 12 performs image processing for each band. First, the central processing unit CPU reads the intermediate code IC-BUF of the band area BND1 from the pointer row PL, gives it to the expansion unit 16, generates RGB bitmap image data, and writes it in the band memory area B-BUF (S14). ). This RGB bitmap image data is multi-value gradation data for each pixel for the three RGB planes, for example, data of 8 bits and 256 gradations, respectively. At this time, as will be described later, the central processing unit CPU obtains an image data existence area where bitmap image data exists in the band area from the intermediate code IC-BUF in the band area BND1. Then, a band memory area B-BUF having a capacity (bandwidth) corresponding to the obtained image data existence area is secured in the memory unit 14, and bitmap image data generated from the intermediate code is written therein. The band memory area secured here does not include both end areas E1 and E2 where the image shown in FIG. 2 is not formed. That is, a band memory area having a width smaller than the width of the print plane (print page) is secured.

  The controller 12 performs color conversion on the RGB bitmap image data in the band memory area (band buffer) B-BUF by the color conversion unit 18, converts it into CMYK bitmap image data, and writes it again in the band buffer B-BUF. (S16). Similarly, this bitmap image data is multi-value gradation data for each pixel, and is data of 8 bits and 256 gradations for four CMYK planes, respectively.

  Further, the controller 12 compresses the CMYK bitmap image data in the band memory area B-BUF by the compression unit 20 and stores it in the same band memory area or another area in the memory unit 14 (S18). The controller 12 decompresses the compressed CMYK bitmap image data in the memory unit, binarizes it by the binarization unit 22, and uses the CMYK binary bitmap image data as the image reproduction data 23 with a pulse width. Output to modulator PWM. Then, the image reproduction signal 16 is supplied to the print engine 24.

  The intermediate code is data having information necessary for generating bitmap image data. By analyzing the information of the intermediate code, the position or region in the band area where the bitmap image data is generated Can be detected. By utilizing this, the image data areas BMR1 and BMR2 in which bitmap image data exists in the band areas BND1 and BND2 shown in FIG. 2 are detected, and the band memory having the bandwidth corresponding to the image data existence area Area B-BUF can be secured. Thereby, the capacity of the band memory area subject to image processing can be reduced.

  FIG. 7 is a diagram for explaining the intermediate code. FIG. 7 shows an image of the band area BND1. As shown in FIG. 7A, the band area BND1 has an origin 0 at the upper left, and is assigned the X axis in the horizontal direction and the Y axis in the vertical direction. In this example, image objects of characters 2-2, rectangles 4-1 and images 6-2 are formed in the band area BND1. FIG. 7B shows information specifying the position where the character 2-2, the rectangle 4-1 and the image 6-2 are formed. That is, the upper left XY coordinate, width, and height of each image object. The intermediate code is a code for expanding the bitmap image data, and has information on the upper left XY coordinate and the width and height for specifying the position of each image object in the XY coordinates in the band area BND1. Yes.

  The intermediate code is not directly related to the expansion of the bitmap, such as the image intermediate code for expanding the above bitmap, character color setting, image object composition method (raster operation) setting, hatch pattern setting, etc. Control intermediate code. In this embodiment, since the control intermediate code is not directly related, the image intermediate code will be described below.

FIG. 8 is a chart showing an example of a rectangular intermediate code. This chart shows intermediate codes, code examples, and descriptions. The rectangular image intermediate code, "rectangular ID" as a rectangle opcode, a rectangular reproduction position "x _rr, y _rr", "w _r" as a rectangle reproduction width, includes "h _r" as a rectangle reproduced height. According to these image intermediate codes, the position in the band region where the image of the rectangle 4-1 exists is specified, and the bitmap image data of the rectangle 4-1 is developed in that region.

  FIG. 9 is a diagram showing source image data of characters and images. In the case of characters, image data of a character bitmap generated in advance is used as source image data. In the character bitmap, image data created from outline font data is stored in the memory unit 14 in the controller, or stored in the ROM. In the case of an image, the source image data is supplied from the host computer and stored in the memory unit 14 in the controller. In any source image data, if the source image width Ws, the source image height Hs, and the pointer Ps to the source data indicating the development start position are specified, the bitmap image data to be developed is specified. Therefore, in addition to these, if the position where the bitmap image data in the band area should be developed is specified by the upper left coordinates, the width and the height on the XY coordinates in the band area, the band memory area B-BUF can be specified. Bitmap image data can be developed.

FIG. 10 is a chart showing an example of an intermediate code between the character 2-2 (part of the character A) and the image 6-2 (part of the image). The character image intermediate code includes “character ID” as the operation code, “x _cr , y _cr ” as the reproduction position, “w _c ” as the reproduction width, and “h _c ” as the reproduction height, similarly to the rectangle. ,
Furthermore, “Ws” is included as the source image width, “Hs” as the source image height, and “Ps” as a pointer to the source data. Similarly, the image intermediate code of the image includes “image ID” as the operation code, “x _ir , y _ir ” as the reproduction position, “w _i ” as the reproduction width, and “h _i ” as the reproduction height. , “Ws” as the source image width, “Hs” as the source image height, and “Ps” as a pointer to the source data.

  As described above, according to the above intermediate code, the source image is specified, and the position to be developed in the band area is specified. Based on this intermediate code, the character 2-2 and the image shown in FIG. 6-2 bitmap image data can be expanded in the band memory B-BUF.

  The printer controller 12 converts the print data PDL supplied from the host computer into the intermediate code and stores the intermediate code in the memory unit 14 for each band area. Then, as shown in FIGS. 7 to 9, the intermediate code includes information for specifying the position or area where the bitmap image data of the image object is to be developed in the band area. Therefore, in the present embodiment, based on the position information of the image object of the intermediate code, the image data existence area in the band area is detected, and the bandwidth corresponding to the image data existence area excluding unnecessary both end areas. The band memory area is secured.

FIG. 11 is a diagram showing a band memory region BMR1 in the band region BND1. In the band area BND1, there are three graphic objects: characters, rectangles, and images. As shown in FIG. 7B, the area (x coordinate value) where each image object is developed is
Character 2-2 is a region rectangle 4-1 from left end x _cr to right end x _cr + w _c -1 and region image 6-2 from left end x _rr to right end x _rr + w _r -1 is a left end x _ir to right end x It becomes a region of _ir + w _i -1.

Therefore, by detecting the minimum left end x-coordinate XL and the maximum right end x-coordinate XR of the development area of the plurality of image objects in these bands, the image data existence area where the bitmap image data of the image object exists is detected. Can do. In the above example, XL = x _cr and XR = x _ir + w _i −1. Therefore, the width of the image data existing region becomes BMR1 = XR-XL + 1 = x ir + w i -x cr. In the present embodiment, a capacity corresponding to the width BMR1 of the image data existence area is secured in the memory unit 14 as a band memory (band buffer) B-BUF. The width BMR1 of the image data existence area is narrower than the width of the printing plane (or printing paper). Then, image processing such as expansion processing, color conversion processing, and compression processing is performed on the image data in the band memory that is minimally required for expansion of the bitmap image data. Therefore, it is possible to reduce the burden of the image processing performed in band units, improve the image processing speed, and increase the printing speed.

  FIG. 12 is a diagram showing the relationship between the image data in the band memory B-BUF and the printing paper. The printing start position LF of the printing paper 1 is defined through a predetermined margin with respect to the left edge PLEFT of the paper. Based on the print start position LF, the print engine 24 forms an image on the printing paper 1. In addition, the controller 12 outputs the image data of each band area to the print engine 24 as an image reproduction signal. Since this image reproduction signal is output with the print start position LF as the origin, the print engine 24 also forms an image according to the received image reproduction signal with the print start position LF as a reference.

  However, in the present embodiment, the image data in each band area has only an image data existence area narrower than the width of the printing paper. Accordingly, when the controller 12 outputs the image reproduction signal to the engine 24 in a dot-sequential manner in the raster direction, the controller 12 can output the image reproduction signal of each band area by shifting the timing by the output offsets OFF1 and OFF2 from the print start position LF. I need it. That is, the controller 12 limits the capacity of the band memory B-BUF to the image data existence area width narrower than the print plane width, and reduces image processing in band units. The image reproduction signal is output to the print engine 24 by shifting. The print engine 24 may form an image on the printing paper in response to the image reproduction signal received with the timing shifted by the output offset.

  According to the present embodiment, in the printing procedure shown in FIG. 5, at the stage where the intermediate code is created in step S12, the image data existence area of each band area is obtained from the intermediate code, and in step S14, the band memory ( Band buffer) The capacity of the B-BUF is limited to the width of the image data existence area. Then, the image processing in steps S14, S16, S18, and S20 is performed on the data in the limited band memory. Further, in step S22, the image reproduction signal generated from the binary bitmap image data is output to the print engine 24 at a timing shifted by the output offset of each band area.

  Hereinafter, image processing according to the present embodiment will be described in detail with reference to flowcharts. The following description is also given by taking the printer controller of FIG. 3A as an example.

  FIG. 13 is a flowchart of processing for one page of print data PDL or one print plane. The controller 12 initializes the minimum left end x-coordinate value XL to output paper width −1 and the maximum right end x-coordinate value to 0 for all band regions (S30). The coordinate values XL and XR are data for obtaining the image data existence area in the band area. Then, the controller 12 reads and interprets the print data PDL for the page (S32). The print data PDL includes image object data and control data, and these data are arranged up to the page break command. If the controller 12 interprets the print data and it is an image object (YES in S34), it creates and registers intermediate codes corresponding to characters, images, and graphics (graphics) (S40, S42, S44). If it is not an image object (NO in S34), if it is not a page break command (NO in S46), a control intermediate command is created and registered (S48). The above intermediate code is created and registered up to the page break command. As a result, an intermediate code for one page is generated and registered for each band area.

  After that, the controller 12 performs bitmap image data expansion processing, color conversion processing, and compression processing for each band area, and stores them in the memory unit 14 (S50).

  FIG. 14 is a flowchart of creation and registration of an intermediate code of an image object. This corresponds to the intermediate code creation and registration processing procedures of intermediate code conversion S12 in FIG. 5 and steps S40, S42, and S44 in FIG. The controller 12 discriminates a band area where an image object is to be formed, and determines a band in which an intermediate code for developing the image object is to be registered (S60). In the example of FIG. 1, since the image object of the character 2 is formed in the bands BND0 and BND1, the intermediate code is registered in the bands BND0 and BND1.

  Next, the controller 12 creates an intermediate code for the print data image object and registers it in the corresponding band. Specifically, the intermediate code is created by referring to a conversion table or the like, and the intermediate code is registered by storing the intermediate code at a corresponding address in the intermediate code buffer IC-BUF shown in FIG. Is called.

  When the controller 12 creates and registers an intermediate code of an image object, the controller 12 obtains an area where bitmap image data is expanded and an image data existence area in each band. This image data existence area is detected by detecting the minimum left end x coordinate XL and the maximum right end x coordinate XR in the band in steps S64 to S70. That is, if the object left end x coordinate of the generated intermediate code is smaller than the minimum left end x coordinate XL (initial value is output paper width −1) (YES in S64), the minimum left end x coordinate XL is updated to the object left end x coordinate. (S66). On the other hand, if the object right end x coordinate of the generated intermediate code is larger than the maximum right end x coordinate XR (initial value is 0) (YES in S68), the maximum right end x coordinate XR is updated to the object right end x coordinate (S70). ). These processes S62 to S70 are performed for all bands in which the image object is to be formed (S72, S74).

The case of the band BND1 in FIG. 7 will be described as an example. The minimum left end x coordinate XL is the left end x coordinate x _cr of the character 2-2, and the maximum right end x coordinate XR is the right end x coordinate x _ir + W _{i of the image.} -1. That is, as described in FIG.

  FIG. 15 is a flowchart of bitmap image data expansion, color conversion, and compression processing. This process corresponds to step S50 in FIG. 13 and corresponds to steps S14, S16, and S18 in FIG. In a state where intermediate codes are generated for a plurality of bands in one page, the band bandNo = 0 is first processed (S80). Then, the controller 12 checks whether or not an intermediate code is registered in the band. If it is registered (YES in S82), the controller 12 performs the process from step S84 onward, and if not registered (NO in S82). ), The next band is selected without performing the process for that band (S98). The determination in step S82 is performed by confirming whether the address ADD is stored in the corresponding band of the pointer string PL in FIG. 6 or whether it is a NULL code. If the address ADD is stored, the intermediate code registered in the band exists in the intermediate code buffer IC-BUF, and if the NULL code remains, there is no intermediate code registered in the band. If there is no intermediate code, there is no need to perform image processing for that band.

  When the intermediate code is registered in the band being processed (YES in S82), the width of the image data existence area in the band area is detected as the band width. Since the minimum left end x-coordinate XL and the maximum right end x-coordinate XR in the band area are obtained in the intermediate code creation and registration processing of FIG. 14, the band width is XR-XL + 1 from these coordinate values XL and XR. (S84). Then, a band memory (band buffer) area corresponding to this bandwidth is secured in the memory unit 14 (S86). As a result, the capacity of the band memory is reduced to the width of the image data existence area narrower than the print plane width.

  Next, the controller 12 initializes by writing “white” data in the band memory B-BUF secured in the memory unit 14 (S88). This “white” data is “FF” for RGB image data, each consisting of a total of 3 bytes of data. If attribute data X is additionally attached, the initial value data for 1 byte of attribute data X is added and totaled. It consists of 4 bytes of data.

  Bitmap image data is developed in the initialized band memory B-BUF based on the intermediate code (S90). Specifically, bitmap image data is written in the band memory B-BUF. However, since the bandwidth of the band memory is narrower than the print plane width, it is necessary to write the image data at a position in the band memory obtained by subtracting the minimum left-end x coordinate value XL from the reproduction position of the image on the printing paper. is there. Then, the process of developing the image data into the band buffer S90 is repeated for all intermediate codes registered in the band bandNo being processed (S92). The generation of image data for each pixel based on the intermediate code is performed by the expansion unit 16 in FIG.

  Further, the controller 12 converts the RGB image data in the band buffer B-BUF into image data in the CMYK color space corresponding to the colorant of the print engine (S94). This color conversion process is performed by the color conversion unit shown in FIG. The color-converted CMYK image data is written again in the band buffer. Then, the controller 12 compresses the color-converted image data and writes it in the memory unit 14. The compression process is performed by the compression unit shown in FIG. Note that binarization processing may be performed on the color-converted image data before compression processing.

  The above image processing is repeated for all bands (S99). According to the present embodiment, in step S86, the controller 12 secures a minimum capacity band memory (band buffer) in the memory unit, and performs initialization processing S88, color conversion processing S94, compression for the capacity. Processing S96 is performed. Since the data capacity to be processed is smaller than that of the conventional print paper width, the burden of this image processing can be reduced.

  FIG. 16 is a flowchart of an image reproduction signal output process to the print engine. FIG. 17 is a diagram showing the timing of the output processing. The controller 12 performs image processing such as color conversion and compression on the bitmap image data developed in the band memory, and then binarizes it by the binarizing unit 22, which is the image reproduction signal 16 by the pulse width modulator PWM. It is converted into a pulse signal and output to the print engine 24. The output to the print engine is performed for the four planes CMYK. When the print engine has a single photosensitive drum, four plane image reproduction signals are output serially. When the print engine is a tandem type having four photosensitive drums, four plane image reproduction signals are output. Output in parallel.

  Hereinafter, the case where four plane image reproduction signals are output serially will be described. First, the controller 12 selects an output plane as a yellow Y plane (S100). Then, the image data of the leading band bndNo = 0 of the output plane is read and output as an image reproduction signal by the above-described processing. If there is image data in the band to be processed (YES in S104), the output offset is set to the minimum left end x coordinate value XL of the band (S106), and the image data of the output plane stored in the memory unit 14 is stored. Is read and expanded (S108), and the binarized and pulse width modulated image reproduction signal is output to the print engine 24 (S110).

  As shown in FIG. 17, the controller 12 synchronizes with the horizontal synchronization signal Hsync shared with the print engine 24, and shifts the image reproduction signal from the timing of the synchronization pulse by the timing of the output offset OFF1 of each band. Outputs dot-sequentially. In the example of FIG. 17, two raster (two rows) image reproduction signals in the band BND1 are output with a timing offset of the output offset OFF1 from the synchronization pulse. Similarly, in the case of another band, the image reproduction signal is output dot-sequentially with the timing shifted by the corresponding output offset.

  When all the image data in the band is output to the print engine, the controller 12 performs the same output processing S104 to S110 for the next band (S112, S114). When the output of all the bands of the current output plane is completed, the same output processing is performed for the next plane (S116, S118). When the image data is output for all the planes, the image processing for that plane ends.

  Similarly, for the next page (plane), the controller 12 similarly generates an intermediate code from the print data PDL, secures a minimum band memory (band buffer) capacity necessary for each buffer, and in units of the band, Performs image processing such as initialization, expansion, color conversion, and compression. When all pages (planes) of the print data are finished, the processing of the print data is finished.

  In the printer configuration shown in FIG. 3B, the printer driver P-DR in the host computer HOST generates an intermediate code IC for each band from the print data PDL, and supplies the intermediate code IC to the printer controller 12. To do. In that case, the printer driver P-DR obtains the minimum left end x coordinate XL and the maximum right end x coordinate XR of each band along with the generation of the intermediate code, and supplies them to the controller 12. Based on the given minimum left end x-coordinate XL and maximum right end x-coordinate XR, the controller 12 specifies an image data existence area in the band area, secures a band memory having a necessary bandwidth, and stores the band data in the band memory. The bitmap image data is expanded to color conversion and compression processing on the image data.

  Therefore, in the printer configuration of FIG. 3B, the processing of FIGS. 13 and 14 is performed by the printer driver P-DR, and the processing of FIGS. Note that the minimum left end x coordinate XL and the maximum right end x coordinate XR of each band may be obtained from the intermediate code IC received by the controller 12.

  In the printer configuration shown in FIG. 3C, the printer driver P-DR in the host computer HOST performs compression by performing intermediate code generation, bitmap image data expansion processing, color conversion processing, and compression processing. The bitmap image data BM is output to the controller 12. In this case, the printer driver P-DR executes the processes of FIGS. 13, 14, and 15 to output the bitmap image data BM and the output offset value of each band to the controller 12. Then, the controller 12 performs the output process of FIG. 16 at a timing according to the output offset value.

  In this case, the printer driver P-DR secures the capacity of the band memory limited to the width of the image data existence area, and performs image processing for the band data of that capacity, thus reducing the data amount of the image processing. be able to.

  As described above, the present embodiment can be applied to any printer configuration. In this case, in the case of the image of FIG. 1, the data amount of the band memory is set to a data amount having a narrower bandwidth than the print plane width, so that it is possible to reduce the burden of image processing in band units.

It is a figure for demonstrating a band area | region. It is a figure explaining the subject of an image processing device. It is a schematic block diagram of the image processing apparatus in this Embodiment. FIG. 2 is a configuration diagram of a printer in the present embodiment. It is a flowchart figure of the printing procedure in this Embodiment. It is a figure which shows the structural example of a memory unit. It is a figure for demonstrating an intermediate code. It is a chart which shows an example of a rectangular middle code. It is a figure which shows the source image data of a character and an image. It is a chart which shows an example of the intermediate code of a character and an image. It is a figure which shows band memory area | region BMR1 in band area | region BND1. It is a figure which shows the relationship between the image data in band memory B-BUF, and printing paper. FIG. 10 is a flowchart of processing for one page of print data PDL. It is a flowchart figure of creation and registration of the intermediate code of an image object. FIG. 5 is a flowchart of bitmap image data expansion, color conversion, and compression processing. It is a flowchart figure of the output process of the image reproduction signal to a printing engine. FIG. 6 is a diagram illustrating timing of output processing of an image reproduction signal to a print engine.

Explanation of symbols

BND1: Band area BMR1: Image data existence area (band width)
XL: Minimum left end x coordinate XR: Maximum right end x coordinate 12: Controller (image processing apparatus)

Claims (5)

In an image processing apparatus that converts print data supplied from a host computer into an intermediate code for each band area obtained by dividing a print plane into a plurality of bands, and generates bitmap image data for each band area based on the intermediate code ,
When generating the intermediate code, an image data existence area where the bitmap image data exists in the band area is obtained by a process of updating with the position information of the generated image object of the intermediate code,
From the obtained image data existence area , the length of the band area in a direction perpendicular to the direction of dividing the print plane is obtained, a band memory area for the length is secured, and the band memory area An image processing apparatus that expands the bitmap image data. In claim 1,
Further, color conversion processing for converting the bitmap image data developed in the band memory area from the first color space to the second color space, and compression processing for compressing the color-converted bitmap image data And an image processing apparatus. In claim 1 or 2,
The image processing apparatus further outputs an image reproduction signal generated from the developed bitmap image data to a print engine in accordance with a position of the image data existing area in the print plane. In claim 1 or 2,
In developing the bitmap image data, an initial value is stored in the band memory area, and the generated bitmap image data is further stored. A host computer that converts print data into an intermediate code for each band area divided into a plurality of print planes and supplies the bitmap image data for each band area based on the intermediate code supplied from the host computer. A system having a printer that generates and outputs an image reproduction signal generated from the generated bitmap image data to a print engine;
When generating the intermediate code, the host computer obtains an image data existence area in which the bitmap image data exists in the band area by a process of updating with the position information of the generated image object of the intermediate code. Supply to the printer,
The printer obtains the length of the band area in the direction perpendicular to the direction of dividing the print plane from the supplied image data existence area, secures a band memory area for the length , A system characterized in that the bitmap image data is expanded in a band memory area.

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