JP5891721B2 - Image processing apparatus and image processing method - Google Patents

Description

  The present invention relates to an image processing apparatus and an image processing method.

  Conventionally, as an image processing apparatus, Huffman decoding, run-length Huffman decoding, and inverse quantization are performed on a sampling target JPEG image, and a pixel out of a total of 64 pixels is obtained for each of the obtained 8 × 8 blocks. There has been proposed a method of sampling and displaying a compressed image by selecting a pixel from which a value is to be acquired and performing an inverse DCT operation on only the selected pixel (see, for example, Patent Document 1). In this apparatus, since the inverse DCT calculation is performed only on the selected pixel, the processing load for sampling and displaying the compressed image can be reduced, and the processing time length can be shortened.

JP 2002-271794 A

  By the way, there is a printing apparatus provided with nozzles having different black resolution and color resolution. In such a printing apparatus, decompression processing of JPEG compressed data in consideration of black resolution and color resolution has not been considered. There has been a demand for reducing the burden and processing time of decompression processing of compressed data used in such a printing apparatus.

  The present invention has been made in view of such problems, and decompression processing of compressed data used in a printing apparatus in which the nozzle resolution for achromatic printing is X times the nozzle resolution for chromatic printing. An object of the present invention is to provide an image processing apparatus and an image processing method that can further reduce the burden and processing time.

  The present invention adopts the following means in order to achieve the main object described above.

The image processing apparatus of the present invention
Used in a printing apparatus in which the nozzle resolution for achromatic printing is X times (X is an integer of 2 or more) with respect to the nozzle resolution for chromatic printing, and has an achromatic and chromatic plane and is accompanied by a DCT operation. An image processing apparatus that generates image data by decompressing compressed data of a compression method,
A decompression processing means for decompressing the compressed data by thinning out pixels at a thinning rate of 1 / X with respect to the achromatic plane;
It is equipped with.

  In this image processing apparatus, a compression having achromatic and chromatic planes and a DCT operation is used in a printing apparatus in which the nozzle resolution for achromatic printing is X times the nozzle resolution for chromatic printing. When decompressing the compressed data of the method and generating the image data, the compressed data is decompressed by thinning out the pixels with a thinning ratio of 1 / X with respect to the achromatic plane. As described above, it is possible to perform the decompression process by thinning the chromatic plane in accordance with the nozzle resolution. For example, the inverse quantization process, the inverse DCT calculation process, and the like can be omitted. Accordingly, it is possible to further reduce the burden and processing time of the decompression processing of compressed data used in a printing apparatus in which the nozzle resolution for achromatic printing is X times the nozzle resolution for chromatic printing. Here, the chromatic printing nozzle may be a color nozzle, the achromatic printing nozzle may be a black nozzle, the chromatic plane may be a Cb plane or a Cr plane, and the achromatic color plane may be a Y plane. Good. The “decimation rate” refers to the ratio of the number of vertical and horizontal pixels after thinning to the number of pixels before thinning, the thinning rate 1 is no thinning, and the thinning rates 1/2, 1/4, 1 / When the value is 8, thinning is performed so that the number of pixels of the image data is reduced. At this time, the decompression processing means may generate the image data by performing dequantization and inverse DCT calculation by thinning out pixels using the set thinning rate.

  In the image processing apparatus of the present invention, when the compressed data in which the resolution of the chromatic plane is equal to the resolution of the achromatic plane is acquired, the thinning ratio of the chromatic plane is set to the achromatic plane. Thinning rate setting means for setting to 1 / X, and the decompression processing means may decompress the acquired compressed data at a thinning rate set by the thinning rate setting means. By so doing, it is possible to further reduce the burden and processing time of decompression processing of compressed data in accordance with the contents of the compressed data. At this time, when the compressed data is acquired, the thinning rate setting unit is configured such that the resolution of the chromatic plane is equal to the resolution of the achromatic color plane based on the resolution of the achromatic color plane and the resolution of the chromatic color plane. In some cases, the thinning ratio of the chromatic plane is set to 1 / X times the thinning ratio of the achromatic color plane, while the resolution of the chromatic plane is 1 / X times the resolution of the achromatic color plane. In some cases, the thinning ratio of the achromatic plane may be set to be equal to the thinning ratio of the achromatic color plane.

  In the image processing apparatus of the present invention adopting an aspect of setting a thinning rate, the thinning rate setting means sets a thinning rate according to a reduction ratio determined based on a designated print size and a decompressed image size. When the achromatic color resolution is printed at X times the chromatic color resolution, the chromatic color plane thinning rate may be set to 1 / X with respect to the achromatic color plane. By so doing, it is possible to further reduce the burden and processing time of the decompression processing of the compressed data in consideration of the print size and the image size.

  In the image processing apparatus of the present invention adopting an aspect of setting a thinning rate, the thinning rate setting unit may set the thinning rate so that the image size after decompression is equal to or larger than a specified print size. Good. In this way, it is possible to further reduce the burden and processing time of the decompression processing of the compressed data while further suppressing the deterioration of the image quality of the printed image.

In the image processing apparatus of the present invention, the nozzle resolution for achromatic printing is 2 ⁿ times (n is a positive number) with respect to the nozzle resolution for chromatic printing, and the decompression processing means is arranged on an achromatic plane. On the other hand, the compressed data may be decompressed by thinning out the pixels of the color plane at a thinning rate of 1/2 ⁿ . Since the compressed data has 2 ⁿ × 2 ⁿ planes, the thinning process can be further simplified, and the burden and processing time of the compressed data decompression process can be more easily reduced.

  In the image processing apparatus of the present invention, the compressed data may be one or more of JPEG data and MPEG data.

The image processing method of the present invention includes:
Used in a printing apparatus in which the nozzle resolution for achromatic printing is X times the nozzle resolution for chromatic printing, and decompresses compressed data of a compression method having achromatic and chromatic planes and DCT operation. An image processing method comprising:
Decompressing the compressed data by thinning out the pixels at a thinning rate of 1 / X with respect to the achromatic plane,
Is included.

  In this image processing method, similarly to the image processing apparatus, it is possible to perform decompression processing by thinning out the color planes in accordance with the nozzle resolution, and it is possible to further reduce the burden and processing time of decompression processing of compressed data. In this image processing method, various aspects of the above-described image processing apparatus may be adopted, and steps for realizing each function of the above-described image processing apparatus may be added.

  The program of the present invention causes one or more computers to realize each step of the above-described control method of the image processing method. This program may be recorded on a computer-readable recording medium (for example, hard disk, ROM, FD, CD, DVD, etc.) or from a computer via a transmission medium (communication network such as the Internet or LAN). It may be distributed to another computer, or may be exchanged in any other form. If this program is executed by a single computer, or if each step is shared and executed by a plurality of computers, each step of the above-described image processing method is executed. Therefore, the same effect as this image processing method can be obtained. can get.

1 is a configuration diagram showing an outline of the configuration of a printer system 10. FIG. FIG. 2 is a configuration diagram showing an outline of the configuration of a print head 31. 6 is a flowchart illustrating an example of a print processing routine. 7 is a flowchart illustrating an example of a thinning and thawing process routine. FIG.

  Next, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of a configuration of a printer system 10 according to the present embodiment. The printer system 10 according to the present embodiment includes a printer 20 as an image processing apparatus according to the present invention, and a personal computer (PC) 40 that is connected to the printer 20 and includes an input device 47 and a display 48 and issues a print instruction. The printer 20 includes a controller 21 that controls the entire printer 20, a reading mechanism 25 that reads a reading document placed on a glass surface, and a printing mechanism 26 that forms an image on a printing medium using a colorant. . The printer 20 controls input / output of data with an interface (I / F) 27 for exchanging information with an external device, an operation panel 28 for receiving display of various information and input from a user, and a memory card. And a memory card reader 30. The printer 20 includes a reading mechanism 25 and a printing mechanism 26, and is configured as a multifunction printer having a printer function, a scanner function, and a copy function. In the printer 20, the controller 21, the reading mechanism 25, the printing mechanism 26, the I / F 27, the operation panel 28 and the memory card reader 30 are electrically connected by a bus 29.

  The controller 21 is configured as a microprocessor centered on the CPU 22, and includes a RAM 23 that temporarily stores data and saves data, and a flash memory 24 that stores various processing programs and can rewrite data. I have. The controller 21 controls the reading mechanism 25 to execute the image reading process and also controls the printing mechanism 26 to execute the printing process.

  The controller 21 also includes a thinning rate setting unit 36, a decompression processing unit 37, and a correction execution processing unit 38 as functional blocks. The thinning rate setting unit 36 executes processing for setting a thinning rate for thinning out pixels when decompressing JPEG data that is compressed data. As will be described in detail later, the thinning rate setting unit 36 matches Cb and Cr planes (color planes; hereinafter also referred to as C and C planes) with respect to the Y plane (achromatic plane) of JPEG data in accordance with the nozzle resolution of the print head 31. A process of setting the thinning rate to 1 / X times is executed. The thinning rate means the ratio of the number of vertical and horizontal pixels after thinning to the number of pixels before thinning, the thinning rate 1 is no thinning, and the thinning rates are 1/2, 1/4, 1/8. Then, thinning is performed so that the number of pixels of the image data is reduced. The decompression processing unit 37 performs processing for decompressing JPEG data and generating image data by performing dequantization and inverse DCT calculation by thinning out pixels using the thinning rate set by the thinning rate setting unit 36. The correction execution processing unit 36 is a processing unit that performs correction on an image, and reflects various correction processes (for example, sharpness and contrast) on the image data using correction values obtained by sampling the image. Execute the process.

  The reading mechanism 25 is of a flat bed type and includes a reading sensor that reads a document placed on a document table as image data (compressed data) and a moving mechanism that moves the reading sensor when reading the document. Configured as an image scanner. The reading sensor is a sensor that separates the reflected light after emitting light toward the document into red (R), green (G), and blue (B) colors to obtain scan data.

  The printing mechanism 26 is configured as a known inkjet color printer mechanism including a print head 31 that performs printing by ejecting ink onto a print medium and a cartridge 34 that supplies ink to the print head 31. The print head 31 ejects ink of each color from the nozzles by applying a voltage to the piezoelectric element to deform the piezoelectric element and pressurize the ink. The mechanism for applying pressure to the ink may be based on the generation of bubbles due to the heat of the heater.

As shown in FIG. 2, the print head 31 includes a nozzle group 33 </ b> C in which nozzles 32 </ b> C, 32 </ b> M, and 32 </ b> Y that can individually eject CMY inks are arranged along the conveyance direction (sub-scanning direction) of the recording paper S. , 33M, 33Y, and nozzle groups 33K1, 33K2 in which nozzles 32K capable of ejecting black (K) ink are arranged along the sub-scanning direction. Here, the configuration of each nozzle group will be described using the cyan (C) nozzle group 33C as an example. The nozzle group 33C is composed of two nozzle rows C1 and C2, and the nozzles 32C are arranged so that each nozzle row C1 and C2 has a predetermined length L in pitch. The nozzles 32C of the nozzle row C1 and the nozzles 32C of the nozzle row C2 are arranged in a zigzag pattern along the sub-scanning direction, and the pitch is a length L / 2 that is half the predetermined length L. ing. In the present embodiment, the predetermined length L is set so that the dots have a resolution of 150 dpi, and the dots formed by the nozzle row C1 and the dots formed by the nozzle row C2 are alternately arranged in the sub-scanning direction. By performing printing so that the dots are arranged in a line, the resolution of cyan (C) dots is 300 dpi. The magenta (M) nozzle group 33M and the yellow (Y) nozzle group 33Y are similarly configured, and the obtained resolution is 300 dpi. Similarly, the black (K) nozzle groups 33K1 and 33K2 include two nozzle rows K11 and K12 and two nozzle rows K21 and K22, respectively. Furthermore, the nozzles 32K of the nozzle group 33K1 and the nozzles 32K of the nozzle group 33K2 are arranged such that the pitch in the sub-scanning direction is a length L / 4 that is half the length L / 2. Therefore, by performing printing so that the dots formed by the nozzle group 33K1 and the dots formed by the nozzle group 33K2 are alternately arranged in a line in the sub-scanning direction, the resolution of the black (K) dots is 600 dpi. Become. As described above, the print head 31 includes a total of 10 nozzle rows, and is configured so that the resolution of CMY dots is 300 dpi and the resolution of K dots is 600 dpi. That is, the nozzle density of K is twice (X times, 2 ⁿ times) higher than the nozzle density of CMY. The printing mechanism 26 uses a black resolution X-fold printing mode in which black resolution is printed at a resolution X times (X = 2 in this case) with respect to color by using the nozzle groups 33K1 and K2, and the nozzle group 33K1. Thus, it is possible to execute the normal printing mode in which black and color are printed at the same resolution.

  The operation panel 28 includes a display unit 28a and an operation unit 28b. Various display screens for selecting and setting menus are displayed on the display unit 28a. The operation unit 28b includes a power key for turning on / off the power, a cursor key for moving the cursor up / down / left / right, a cancel key for canceling the input, a determination key for determining the selection, and the like. Can be entered.

  The memory card reader 30 inputs and outputs data with the memory card inserted in the slot. The memory card reader 30 reads out a file stored in the memory card and sends it to the controller 21 or inputs a command from the controller 21 when the memory card is loaded, and receives data from the memory card based on the command. Or write.

  Next, the operation of the printer 20 of the present embodiment configured as described above, particularly the operation when the JPEG data is decompressed and the decompressed image is subjected to print processing will be described. Here, the process of mainly reading JPEG data stored in a memory card, performing pixel thinning processing, and decompressing the JPEG data will be specifically described. First, the user attaches a memory card to the memory card reader 30 and selects JPEG data to be printed on a print selection screen (not shown). The user operates various keys of the operation unit 28b to select an image to be printed, and presses a print execution key (not shown). Then, the CPU 22 executes a print processing routine stored in the flash memory 24. FIG. 3 is a flowchart illustrating an example of a print processing routine executed by the CPU 22 of the controller 21. In this routine, the CPU 22 uses the thinning rate setting unit 36, the decompression processing unit 37, and the correction execution processing unit 38 to perform JPEG data decompression processing (print image generation processing).

  When the print processing routine of FIG. 3 is started, the CPU 22 first acquires print setting information from the information stored in the JPEG data tag and the input content on the operation panel 28 (step S100). The print setting information includes JPEG data component information (4: 4: 4, 4: 2: 2 and 4: 2: 0), and black resolution X times the color resolution (X = 2). ) Includes information indicating whether the black resolution X-times print mode for printing is selected or the normal print mode is selected. The print setting information includes information on whether or not to execute correction processing such as image size of JPEG data, print paper size (print size), sharpness processing, contrast processing, and noise removal processing. .

  Next, the CPU 22 determines whether or not reduction printing of 1/8 or more is possible from the print size and the image size of JPEG data (step S110), and reduction printing of 1/8 or more is possible. In some cases, the thinning rate of the Y plane of JPEG data is set to 1/8, and the thinning rate of the C and C planes is set to 1/8 (step S120). On the other hand, if 1/8 or more reduced printing is not possible, it is determined whether or not 1/4 or more reduced printing is possible (step S130). If 1/4 or more reduced printing is possible, Y is determined. The thinning rate of the plane is set to 1/4 and the thinning rate of the C and C planes is set to 1/4 (step S140). On the other hand, when the reduction printing of 1/4 or more is not possible, it is determined whether or not the reduction printing of 1/2 or more is possible (step S150), and when the reduction printing of 1/2 or more is possible, Y The thinning rate of the plane is set to 1/2, and the thinning rate of the C and C planes is set to 1/2 (step S160). On the other hand, when reduced printing of 1/2 or more is not possible, the thinning rate of the Y plane is set to 1 and the thinning rate of the C and C planes is set to 1 (step S170). That is, the thinning rate is set so as not to perform the thinning process. In this way, the thinning rate is set so that the image size after decompression is equal to or larger than the designated print size. The thinning rate is set using the thinning rate setting unit 36.

  After setting the thinning rate in step S120, step S140, step S160, and step S170, the CPU 22 determines whether or not the black resolution X-times print mode is selected (step S180), and the black resolution X-times print mode is set. If it is selected, it is determined whether or not the Y plane and the C and C planes have the same resolution (step S190). Here, when the components of JPEG data are 4: 4: 4 and 4: 2: 2, it is determined that the Y plane and the C and C planes have the same resolution, and the components of JPEG data are 4: 2: 2. When it is 0, it is determined that the C and C planes have the same resolution of 1/2 with respect to the Y plane. When the Y plane and the C and C planes have the same resolution, it is determined whether or not the thinning rate of the C and C planes can be changed (step S200). In this determination, for example, when the thinning rate of the C and C planes is 1/8, it is determined that the thinning rate is not changeable. When the black resolution X-times printing mode is not selected at step S180, that is, when the normal printing mode is selected, when the Y plane and the C, C plane are not at the same resolution at step S190, that is, C, C When the plane is half the resolution of the Y plane, or when the thinning rate of the C and C planes is not changeable (decimation rate 1/8) in step S200, the interval set in steps S120 to S170 The thinning and thawing process is executed with the pull rate (step S210).

  Here, the thinning and thawing process will be described. FIG. 4 is a flowchart illustrating an example of the thinning and thawing process routine. This routine is executed using the decompression processing unit 37. When this routine is executed, the CPU 22 performs entropy decoding (Huffman decoding) on the JPEG data (step S300), group decoding (step S310), and run length decoding (step S320). As a result, N × N (for example, N = 8) pre-quantization DCT coefficient frequency blocks are obtained. In this state, a so-called thinning process using only a desired value from the N × N block is possible. Next, the CPU 22 determines whether or not to perform the decimation / decompression process based on the set decimation rate (step S330). When the decimation / decompression process is not performed (decimation rate = 1), the DCT coefficient is determined. All are selected (step S340), DCT coefficient inverse quantization is performed on the frequency block of the DCT coefficient (step S350), inverse discrete cosine transform (IDCT) is performed (step S360), and the minimum coding unit (MCU). Processing and color conversion are performed (step S370), image data is stored (step S380), and this routine is terminated. Among these processes, the inverse DCT operation has the largest processing load, and the process takes time. Since the inverse DCT calculation is detailed in Japanese Patent Application Laid-Open No. 2002-271794, the description thereof is omitted. In the MCU process and the color conversion, for example, the pixel value obtained by the process may be corrected using an empirically determined correction coefficient. Note that the inverse quantization and inverse discrete cosine transform of the DCT coefficient are performed for each of the Y, C, and C planes.

  On the other hand, when the decimation / decompression process is performed in step S330, the DCT coefficient is decimation selected (step 390). FIG. 5 is a conceptual diagram of the thinning and thawing process. As shown in FIG. 5, in the case of thinning out frequency blocks of 8 × 8 DCT coefficients at a thinning rate of 1/2, for example, 4 out of a total of 64 8 × 8 blocks multiplied by 1/2 in the vertical and horizontal directions, respectively. The frequency components for the subsequent processing are selected so that a total of 16 × 4 pieces remain in a distributed manner. In addition, when thinning at a thinning rate of 1/4, for example, out of a total of 64 of 8 × 8 blocks, 2 × 2 multiplied by 1/4 each in length and width, so that a total of 4 remains in a distributed manner. A frequency component to be processed thereafter is selected. In addition, when thinning at a thinning rate of 1/8, for example, select frequency components for subsequent processing so that one of 8 × 8 blocks multiplied by 1/8 is left. To do. Then, the DCT coefficient inverse quantization, IDCT, MCU processing, and color conversion are performed on the selected DCT coefficient in the same manner as in steps S350 to S380, and the pixel of each plane is obtained. When each DCT coefficient is processed, a zigzag scan may be performed as shown in the upper part of FIG. In this way, the processing speed can be further increased. In this way, the number of inverse DCT operations with a large processing load can be reduced according to the thinning rate, and the processing load and processing time can be further reduced. In step S180, if the black resolution X-times printing mode is not used, the Y plane and the C and C planes are not the same resolution, and if the C and C plane thinning rates cannot be changed (thinning rate 1/8), The thinning process is executed with the thinning rate set in steps S120 to S170.

  Now, the description returns to the print processing routine of FIG. If the black resolution X times printing mode is selected in step S180, the Y plane and the C and C planes have the same resolution in step S190, and the thinning rate of the C and C planes can be changed in step S200, the C , C plane thinning rate is further set to 1 / X times (X = 2 in this case) (step S220), and the thinning / decompression process of step S210 is executed. That is, when printing with the color nozzle resolution set to 1 / X with respect to the black nozzle resolution, the thinning rate is set so that the resolution of the C and C planes becomes 1 / X with respect to the resolution of the Y plane. To do. In this way, since the thinning rate of the C and C planes is further reduced to 1 / X, the decompression processing load and processing time are further reduced as compared with the case where the decompression processing is performed at the thinning rates set in steps S120 to S170 described above. be able to.

  After executing the thinning / decompression process in step S210, the CPU 22 performs a simple padding process for pixels so that the resolution of the C and C planes is the same as the resolution of the Y plane as necessary (step S230). An enhancement process for performing YCC color conversion is executed (step S240). The enhancement processing is performed by the correction execution processing unit 38. For example, the decompressed image color is corrected to a color suitable for the printer 20 using an empirically obtained YCC-YCC correspondence (for example, a lookup table). It is good also as processing to do. Subsequently, an ink color conversion process from YCC to CMYK image data is executed (step S250), a print process is executed (step S260), and this routine is terminated. Ink color conversion uses an YCC-CMYK correspondence relationship (for example, a look-up table) obtained empirically to perform processing for conversion to an ink color used in the printer 20. In the printing process, in the printing in the normal printing mode, the printing process is executed using the nozzle groups 33C, 33M, 33Y, and 33K1. On the other hand, in printing in the black resolution X-times printing mode, printing processing is executed using the nozzle group 33K2 so that the black resolution is X times.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. In this embodiment, the thinning rate setting unit 36 corresponds to a thinning rate setting unit, and the decompression processing unit 37 corresponds to a decompression processing unit. In the present embodiment, an example of the image processing method of the present invention is also clarified by describing the operation of the printer 20.

According to the printer 20 of the present embodiment described in detail above, the print head 31 has a black (achromatic) printing nozzle resolution of X times the color (chromatic) printing nozzle resolution, and the Y plane. In contrast, JPEG data (compressed data) is decompressed by thinning pixels of the C and C planes at a thinning rate of 1 / X. As described above, the C and C planes can be thinned and decompressed in accordance with the nozzle resolution. For example, inverse quantization processing, inverse DCT calculation processing, and the like can be omitted. Therefore, it is possible to further reduce the burden and processing time of JPEG data decompression processing. When JPEG data having the same resolution of the C and C planes as the resolution of the Y plane is acquired, the thinning rate of the C and C planes is set to 1 / X for the Y plane. Since the JPEG data is decompressed at the pull rate, the burden of decompression processing and the processing time can be further reduced according to the contents of the JPEG data. Furthermore, when setting the thinning rate in accordance with the reduction ratio determined based on the designated print size and the decompressed image size, and printing the black resolution at X times the color resolution, the Y plane On the other hand, since the thinning rate of the C and C planes is set to 1 / X, it is possible to further reduce the burden and processing time of the decompression processing of the compressed data in consideration of the print size and the image size. Furthermore, since the decimation rate is set so that the image size after decompression is greater than or equal to the specified print size, the burden and processing time of decompression processing of compressed data is further reduced while further suppressing the degradation of the print image quality. can do. Then, the black nozzle resolution is 2 ⁿ times the color nozzle resolution, and the compressed data is decompressed by thinning out the pixels at a thinning rate of 1/2 ⁿ between the C plane and the C plane with respect to the Y plane. Since the compressed data has 2 ⁿ × 2 ⁿ planes, the thinning process can be further simplified, and the burden and processing time of the decompression process of the compressed data can be more easily reduced. In addition, since JPEG data often used as image data is thinned and decompressed, it is highly significant to apply the present invention. Furthermore, since the performance of the controller is limited in devices such as the printer 20, it is highly meaningful to apply the present invention.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the thinning rate is set by the thinning rate setting unit 36, but the C and C planes are thinned with the 1 / X thinning rate with respect to the Y plane, and the compressed data is obtained. If it defrosts, it will not specifically limit to this, You may abbreviate | omit the setting of a thinning rate. For example, JPEG data of 4: 4: 4 and 4: 2: 2 components may be printed only in the black resolution X-times print mode. Even in this case, it is possible to further reduce the burden and processing time of the decompression processing of the compressed data.

  In the embodiment described above, based on the resolution of the Y plane and the resolution of the C and C planes, when the resolution of the C and C planes is the same as the resolution of the Y plane, While the thinning rate of the C plane is set to 1 / X, when the resolution of the C and C planes is 1 / X times the resolution of the Y plane, the thinning rate of the C and C planes to the thinning rate of the Y plane However, the present invention is not limited to this, and consideration of the resolution of each plane may be omitted. Even in this case, if the compressed data is decompressed by thinning out the pixels at the 1 / X thinning rate for the C and C planes with respect to the Y plane, it is possible to further reduce the burden of decompression processing and the processing time.

  In the above-described embodiment, the thinning rate is set according to the reduction ratio determined based on the designated print size and the decompressed image size, and the black resolution is printed at X times the black resolution (black When printing with a resolution of X times, the thinning rate of the C and C planes is set to 1 / X for the Y plane. However, the present invention is not limited to this, and the setting of the thinning rate based on the reduction ratio is omitted. It is also possible to set the thinning rate of the C and C planes to 1 / X for the Y plane without being limited to black resolution X-times printing. Even in this case, it is possible to further reduce the burden and processing time of the thawing process.

  In the above-described embodiment, the thinning rate is set so that the image size after decompression is equal to or larger than the specified print size. However, the thinning rate may be set without considering the print size. Even in this case, it is possible to further reduce the burden and processing time of the thawing process.

In the above-described embodiment, the black nozzle resolution is twice (X times) the color nozzle resolution, and the C and C planes are thinned out with respect to the Y plane at a half rate. However, it is not particularly limited, and X is not particularly limited as long as it is an integer of 2 or more. Alternatively, X = 2 ⁿ (n is a positive number). Since the compressed data has 2 ⁿ × 2 ⁿ planes, the thinning process can be further simplified.

  In the above-described embodiment, the compressed data stored in the memory card attached to the memory card reader 30 is decompressed and printed. However, the compressed data with the DCT operation is decompressed to generate image data. For example, the compressed data read by the reading mechanism 25 may be decompressed, or the compressed data transmitted from the PC 40 may be decompressed.

  In the above-described embodiment, the compressed data is described as JPEG data. However, the compressed data is not particularly limited as long as the compressed data includes achromatic and chromatic planes and includes DCT calculation. For example, MPEG data may also be used. Good. In the above-described embodiments, the color nozzle and the black nozzle have been described. However, the chromatic printing nozzle and the achromatic printing nozzle may be used. Further, although described as a Cb, Cr plane or Y plane, it may be a chromatic plane or an achromatic plane.

  In the above-described embodiments, the multifunction printer capable of executing printing, scanning, and copying has been described as the image processing apparatus of the present invention. However, a printer alone, a scanner alone, a FAX, or the like may be used. Or it will not specifically limit if it is an apparatus which decompress | decompresses the compression-type compressed data with DCT calculation, and produces | generates image data, For example, information processing equipment, such as a personal computer and a notebook personal computer, a digital still camera, a digital video camera It may be a photographing device, a video device such as a digital TV or an HDD recorder, a portable or home game device, or a communication device such as a mobile phone. The reading mechanism 25 is a flatbed type that fixes an original and moves a reading sensor to read an image, but may adopt a method in which the reading sensor is fixed and the original is moved and read. Further, although the printing mechanism 26 is an inkjet method, it may be an electrophotographic method, a thermal transfer method, or a dot impact method. Further, although the present invention has been described in the form of the printer 20, it may be in the form of an image processing method or in the form of a program for this method.

  10 Printer System, 20 Printer, 21 Controller, 22 CPU, 23 RAM, 24 Flash Memory, 25 Reading Mechanism, 26 Printing Mechanism, 27 Interface (I / F), 28 Operation Panel, 28a Display Unit, 28b Operation Unit, 29 Bus , 30 Memory card reader, 31 Print head, 32C, 32M, 32Y, 32K Nozzle group, 33C, 33M, 33Y, 33K1, 33K2 Nozzle, 34 Cartridge, 36 Thinning rate setting unit, 37 Defrosting processing unit, 38 Correction execution processing unit , 40 PC (PC), 47 input device, 48 display, S recording paper.

Claims (8)

Used in a printing apparatus in which the nozzle resolution for achromatic printing is X times (X is an integer of 2 or more) with respect to the nozzle resolution for chromatic printing, and has an achromatic and chromatic plane and is accompanied by a DCT operation. An image processing apparatus that generates image data by decompressing compressed data of a compression method,
A decompression processing means for decompressing the compressed data by thinning out pixels at a thinning rate of 1 / X with respect to the achromatic plane ;
An image processing apparatus. The image processing apparatus according to claim 1,
When the compressed data having the same resolution of the chromatic plane as the resolution of the achromatic plane is acquired, the decimating ratio for setting the decimating ratio of the chromatic plane to 1 / X with respect to the achromatic plane Setting means,
The decompression processing unit decompresses the acquired compressed data at a thinning rate set by the thinning rate setting unit . When the compressed data is acquired, the thinning rate setting unit is based on the resolution of the achromatic plane and the resolution of the chromatic plane, and when the resolution of the chromatic plane is equal to the resolution of the achromatic plane, While the thinning ratio of the chromatic color plane is set to 1 / X times the thinning ratio of the achromatic color plane, when the resolution of the chromatic color plane is 1 / X times the resolution of the achromatic color plane, The image processing apparatus according to claim 2 , wherein a thinning ratio of the chromatic plane is set to be equal to a thinning ratio of the chromatic plane .   The thinning rate setting unit sets a thinning rate according to a reduction ratio determined based on a designated print size and a decompressed image size, and prints the achromatic color resolution at X times the chromatic resolution. 4. The image processing apparatus according to claim 2, wherein the thinning ratio of the chromatic color plane is set to 1 / X with respect to the achromatic color plane.   The image processing apparatus according to claim 2, wherein the thinning rate setting unit sets the thinning rate so that the image size after the decompression is equal to or larger than a specified print size.   Nozzle resolution for achromatic printing is 2 compared to nozzle resolution for chromatic printing ⁿ Times (n is a positive number)
  The decompression processing means halves the chromatic plane with respect to the achromatic plane. ⁿ The image processing apparatus according to claim 1, wherein the compressed data is decompressed by thinning pixels at a thinning rate. The compressed data, JPEG data is any one or more of the MPEG data, the image processing apparatus according to any one of claims 1-6.   Used in a printing apparatus in which the nozzle resolution for achromatic printing is X times the nozzle resolution for chromatic printing, and decompresses compressed data of a compression method having achromatic and chromatic planes and DCT operation. An image processing method comprising:
  Decompressing the compressed data by thinning out the pixels at a thinning rate of 1 / X with respect to the achromatic plane,
  An image processing method including:

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