JP2008015943A - Image processor and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the capacity of a print buffer arranged to absorb fluctuations of a processing time resulting from the drop of a hit rate. <P>SOLUTION: The image processor comprising a pre-processing part 102 for performing color space conversion processing of image data and a post-processing part 104 for using a LUT (lookup table) to perform color separation of the image data subjected to the color space conversion processing is provided with a data separating and compressing part 114 for separating integral part data for extracting a lattice point of the LUT from the image data subjected to the color space conversion processing and using a slide dictionary to compress the integral part data, and the print buffer 103 for storing the compressed integral part data, wherein the post-processing part 104 reads the compressed integral part data from the print buffer 103, uses the slide dictionary to generate integral part data for extracting the lattice point data and subsequently performs color separation using the LUT. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image processing technique in an image processing apparatus arranged in a printing apparatus.

  In recent years, various color input devices such as scanners and video cameras have become widespread as input devices. As output devices, various color output devices such as an ink jet, a dye thermal sublimation type, or an electrophotographic color printer have become widespread.

  In general, each of these color input / output devices has a unique color space. For this reason, for example, when a color image obtained by a certain scanner is transferred to another color printer as it is and printed, the color of the printed color image is almost the same as the color of the original color image read by the scanner. Absent.

  In order to solve the problem of color reproducibility between input / output devices for such color images, the input / output device usually performs processing for converting the color space of the input device to the color space of the output device ( This function is called “color space conversion process”.

  This color space conversion processing refers to a series of image processing such as input γ correction, luminance density conversion, masking, black generation, UCR, output γ correction, or a part of the image processing. Specifically, the digital image data of the three colors (red, blue, green, hereinafter abbreviated as “RGB”) of the input device are simultaneously referred to, and the three colors (cyan, magenta, yellow) of the output device are simultaneously referred to. A process of converting into digital image data of three colors (hereinafter, “CMY”). Alternatively, it refers to a process of converting into digital image data of four colors (four colors of cyan, magenta, yellow, and black, hereinafter “CMYK”).

  The color space conversion process can be realized by performing association from space to space. A plurality of methods for performing such conversion have been proposed so far, and among them, a three-dimensional lookup table (3D-) shown in JP-A-53-123201 and JP-A-8-237497 is disclosed. A method that combines LUT) and interpolation is often used. Further, there are various methods for color space conversion processing combining 3D-LUT and interpolation. Of these, tetrahedral interpolation disclosed in Japanese Patent Application Laid-Open No. 53-123201 is used because of necessary data amount, necessary calculation amount, output continuity between unit cuboids, gray line interpolation characteristics, and the like. Many.

  However, in the case of the color space conversion process by the 3D-LUT + interpolation, if the number of grid points per axis of the 3D-LUT (hereinafter referred to as “grid number”) is increased in order to improve the accuracy of the color space conversion process, The capacity of the 3D-LUT increases by the third power. Recently, digital cameras to which color filters other than RGB are added as input devices in order to improve color reproducibility have appeared. In this case, the LUT capacity increases by the fourth power of the number of grids. Large memory capacity is required.

  Furthermore, output devices such as color printers have appeared that use a large number of color materials (inks) in order to improve color reproducibility, gradation, and graininess. In this case, the LUT has a capacity of color. Since the number increases in proportion to the number of materials, an enormous memory capacity is required.

In order to solve such an increase in memory capacity, a technique that incorporates a cache mechanism is often used at present. For example, in Japanese Patent Application Laid-Open No. 2004-274131, first, a cache memory composed of independent small-capacity memories is provided at each vertex, and a memory that is shared by these cache memories and accessed in a time division manner is further provided. By storing all of the LUT in the shared memory, it is possible to reduce the total capacity of the LUT memory and reduce the cost while suppressing the performance degradation.
JP-A-53-123201 JP-A-8-237497 JP 2004-274131 A

  However, in the case of the method incorporating the cache mechanism as described above, the cache hit rate changes depending on the input image data, and the DRAM reference count fluctuates, so that the time required for color space conversion processing varies. . For this reason, there is a problem that the real-time property in the color space conversion process cannot be guaranteed.

  On the other hand, in order to guarantee the real-time property, a method of arranging a print buffer or the like after the color space conversion process and absorbing the fluctuation in the required time by the print buffer can be considered. However, with the recent increase in resolution and the increase in the number of nozzles of the print head, an increase in the capacity and bandwidth of the print buffer has become a problem, and such a method is not appropriate.

  The present invention has been made in view of the above problems, and suppresses the capacity of a print buffer that absorbs fluctuations in processing time due to a decrease in hit rate in color space conversion processing using a cache mechanism, thereby reducing cost. The purpose is to reduce.

In order to achieve the above object, an image processing apparatus according to the present invention comprises the following arrangement. That is,
An image processing apparatus comprising: a first processing unit that performs color space conversion processing on image data; and a second processing unit that performs color separation on the image data subjected to the color space conversion processing using an LUT.
Separation means for separating first data for extracting the lattice point data of the LUT from the image data subjected to the color space conversion processing;
Compression means for compressing the separated first data using a slide dictionary;
Storing means for storing the compressed first data,
The second processing means uses the LUT after reading the compressed first data from the storage means and generating first data for extracting the grid point data using a slide dictionary. It is characterized by color separation.

  According to the present invention, it is possible to reduce the cost of a print buffer that absorbs fluctuations in processing time caused by a decrease in hit rate in color space conversion processing using a cache mechanism, thereby realizing cost reduction. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings as necessary.

[First Embodiment]
<Functions of each part of the printing device>
FIG. 1 is a diagram illustrating a functional configuration of a printing apparatus (for example, a printer with a scanner function, hereinafter referred to as “multifunction printer”) including an image processing apparatus according to the first embodiment of the present invention.

  A sensor 101 reads an original and generates image data. A pre-processing unit 102 performs processing such as shading correction processing, input γ conversion processing, color conversion processing, and color correction processing on the image data generated by the sensor 101.

  Reference numeral 114 denotes a data separation / compression unit that separates image data that has been subjected to each process by the pre-processing unit 102 and performs compression processing on the separated image data. Reference numerals 103 and 113 denote print buffers, which temporarily store the separated and compressed image data.

  A post-processing unit 104 performs color separation processing on the image data stored in the print buffer 103 or 113 and quantizes the image data. A printer engine 105 prints on a recording medium such as paper based on the image data quantized by the post-processing unit 104.

  The upstream processing unit 102 further includes an input device processing unit 106 and a color correction processing unit 107. The input device processing unit 106 performs known shading correction, input γ processing, color conversion processing, and the like. The color correction processing unit 107 includes a cache mechanism and an interpolation calculation unit, and performs color correction processing. Reference numeral 109 denotes a 3D-LUT for color correction processing.

  Further, the post-processing unit 104 includes a color separation processing unit 110 and a quantization processing unit 112. Reference numeral 111 denotes an LUT for color separation processing. Here, the color separation processing LUT 111 is a 3D-LUT, similar to the color space correction processing LUT 109. Similarly to the color correction processing unit 107, the color separation processing unit 110 includes a cache mechanism and an interpolation calculation unit.

<Overall operation of multi-function printer>
Next, the overall operation of the multifunction printer of FIG. 1 will be described. When the document is read by the sensor 101, the input device processing unit 106 of the pre-processing unit 102 receives image data in the RGB color space (hereinafter referred to as SD-RGB data) from the sensor 101.

  The input device processing unit 106 that has received the SD-RGB data performs input device processing such as shading correction, input γ correction processing, and color conversion processing. Then, the image data in the standard color space after the input device processing (hereinafter referred to as aRGB data) is output to the color correction processing unit 107.

  The color correction processing unit 107 that has received the aRGB data performs color correction processing using a cache mechanism, and outputs the corrected aRGB data as RGB (hereinafter referred to as PD-RGB) data of the multifunction printer.

  In the data separation / compression unit 114 that has received the PD-RGB data, an integer part (hereinafter referred to as integer part data) that is used to generate an address of the color separation processing LUT and a decimal number that is used to generate an interpolation coefficient. Parts (hereinafter referred to as decimal part data). The PD-RGB data separated into the integer part data and the fractional part data is compressed separately (the compressed data of the integer part data is referred to as the integer part compressed data, and the compressed data of the fractional part data is referred to as the fractional part compressed data). Called).

  The generated integer part compressed data is stored in the print buffer 103, and the decimal part compressed data is stored in the print buffer 113. The print buffer 103 and the print buffer 113 play a role of absorbing a penalty due to a miss hit in the cache mechanism of the color correction processing unit 107. The print buffers 103 and 113 output the integer part compressed data and the fractional part compressed data to the color separation processing unit 110 of the post-processing unit 104, respectively.

  The color separation processing unit 110 decompresses the integer part compressed data and the fractional part compressed data while performing color separation processing using a cache mechanism, and images of CMYK, light C, and light M, which are color spaces of the multifunction printer. Data is generated and output to the quantization processing unit 112. The quantization processing unit 112 that has received the CMYK, light C, and light M image data performs quantization processing and outputs the generated quantized data to the printer engine 105 as print data. Based on this, the printer engine 105 executes print processing.

<Configuration of Data Separation / Compression Unit 114>
Next, the configuration of the data separation and compression unit 114 will be described in detail with reference to FIG. FIG. 2 is a diagram illustrating details of the data separation / compression unit 114. As shown in the figure, the data separation / compression unit 114 includes a data separation unit 201, a compression unit 203, a selector 207, and a compression unit 209.

  The data separation unit 201 receives the PD-RGB data output from the pre-processing unit 102 and separates it into an upper bit signal (= integer part data) and a lower bit signal (= decimal part data). The integer part data is an address used when accessing the color separation processing LUT 111, and the fractional part data is used for the interpolation operation and is stored in the color separation processing LUT 111 (hereinafter referred to as grid point data and This data is used when selecting " The integer part data is output to the compression unit 203, and the decimal part data is output to the selector 207.

  The compression unit 203 performs compression using the slide dictionary method on the input integer part data while reading and writing to the slide dictionary 205, and outputs integer part compressed data. By using the slide dictionary method for compressing the integer part data, the reference reading unit 401 described later determines whether or not the target lattice point data is written in the slide dictionary 403 described later to the reference reading unit 401. This can be performed based on the state of data input. The data input state here refers to a compressed or uncompressed state.

  The compression unit 209 is a means for compressing the fractional part data and may be any compression that reduces the capacity of the print buffer 113, and thus detailed description thereof is omitted.

  The selector 207 selects whether the decimal part data is compressed by the compression unit 209 or directly bypassed. Specifically, the grid point data selection by the grid point data selection unit 407 is desired due to the long processing time when decompressing the data compressed by the compression unit 209 in the decompression unit 405 described later. Select to bypass and output when it is determined that the cycle is not in time. The output decimal part compressed data is stored in the print buffer 113.

<Description of slide dictionary method>
A slide dictionary method used in the compression unit 203 will be described. First, a known slide dictionary method will be described. According to a known slide dictionary method, first, a character string pattern is extracted from an input character string to be compressed, and a character string that matches the extracted character string pattern is searched. At this time, the search is performed on an input character string ahead of the extracted character string in the input character string. When a character string pattern (longest matching pattern) that matches the extracted character string pattern is detected in the input character string ahead, the longest matching pattern is input as the longest matching pattern. Replace with position and length in the string. In this way, the input character string is compressed.

The details of the sliding-dictionary method are disclosed in the following documents, for example.
・ The section “LZ method” on pages 389 to 393 of Haruhiko Okumura “Latest Algorithm Encyclopedia in Software Technology 13C Language” (December 10, 1991, Technical Critics) ・ SoftBank Japan “C MAGAZINE 1991.1” “Special Feature Introduction to Compression Algorithm” on pages 44 to 68 On the other hand, the slide dictionary method used in this embodiment differs from the above-described known slide dictionary method in that the position of the longest matching pattern in the input character string is The feature is that the compression is not performed by the length but by the position (entry) and the continuous number (run length) in the slide dictionary. This is because in the image data, the correlation between neighboring pixels is strong, and since the integer part data uses the upper bit signal of the PD-RGB data, the probability that the same value continues is very high. .

<Processing Flow in Compression Unit 203>
Next, the flow of processing in the compression unit 203 will be described with reference to FIG. FIG. 3 is a diagram illustrating a processing flow in the compression unit 203 that processes the integer part data output from the data separation unit 201. FIG. 3 shows the flow of processing for one data of continuous integer part data (that is, in order to process all continuous integer part data, the processing cycle of FIG. 3 is repeated a plurality of times. Will be.)

  In step S301, it is determined whether or not the integer part data received from the data separation part exists in the slide dictionary 205. If it is determined that it exists, the process proceeds to step S302, where it is determined whether or not the current integer part data is the same as the integer part data processed in the previous cycle (that is, the integer part data having the same value is continuous). Or not).

  If it is determined in step S302 that they are different, the process proceeds to step S303, and among the entries in the slide dictionary 205, the entry corresponding to the current integer part data is output, and then the process proceeds to step S304. On the other hand, if it is determined in step S302 that they are the same, the process directly proceeds to step S304. In step S304, the value of the continuous number counter is incremented.

  In step S305, it is determined whether or not the current integer part data is the last data when the same value continues. If it is determined that the data is the last data, the process proceeds to step S306. In step S306, after the value of the continuous number counter is output, the value of the continuous number counter is set to zero, and the process for the current integer part data is terminated. On the other hand, if it is determined that it is not the last data, the process for the current integer part data is terminated without going through step S306.

  On the other hand, if it is determined in step S301 that it does not exist, the process advances to step S307 to write the integer part data in the slide dictionary 205. Further, in step S308, the integer part data is output without being compressed, and the process for the current integer part data is terminated.

<Specific Example of Processing in Compression Unit 203>
Next, a specific example of processing in the compression unit 203 will be described in correspondence with FIG. Here, the integer part data output from the data separator 201 is “A”, “A”, “A”, “A”, “B”, “B”, “B”, “C”, “C”. , “D”, “E”, “A”, “B”, “C” are input to the compression unit 203 in this order as an example.

  Initially, since the slide dictionary 205 is empty (“No” in step S301), first, “A” of the head data of the integer part data is written in the entry “0” area of the slide dictionary 205 (step S307). Then, “A” is output as integer part compressed data (step S308).

  The next integer part data “A” is written in entry “0” of the slide dictionary 205 (“Yes” in step S301), and is different from the integer part compressed data output in the previous cycle. Data (“No” in step S302). Therefore, “0” is output as integer part compressed data (step S303). Further, since the continuous number counter is incremented, the continuous number counter is changed from 0 to 1 (step S304).

  After outputting the second integer part compressed data, it is determined whether or not the continuous data is the last data (step S305), and if it is not the last data, the second integer part data is determined. The process ends.

  The next integer part data “A” is written in the entry “0” of the slide dictionary 205 (“Yes” in step S301), and is the same data as the integer part compressed data output in the previous cycle. ("Yes" in step S302). Further, since it does not correspond to the last integer part data when the same value continues, after incrementing the continuous counter (1 → 2) (step S304), the process for the third integer part data is terminated. ("No" in step S305).

  The next integer part data “A” is written in the entry “0” of the slide dictionary 205 (“Yes” in step S301), and is the same data as the integer part compressed data in the previous cycle (in step S302, “ Yes "). Therefore, the continuous counter is incremented (2 → 3) (step S304). Further, since “A” corresponds to the last integer part data when the same value continues (“Yes” in step S305), the value (3) of the continuous counter is output and then the value of the continuous counter is changed to “ It is cleared to “0” (step S306).

  By repeating the above processing, “A”, “0”, “3”, “B”, “1”, “2”, “C”, “2”, “1”, “D”, “5” ”,“ E ”,“ 0 ”,“ −1 ”,“ 1 ”,“ 1 ”,“ 2 ”,“ 1 ”in this order, the integer part compressed data is generated.

  It is assumed that the order of writing the integer part data in the slide dictionary 205 is the entry number order. Further, when writing to the slide dictionary 205 after writing to the slide dictionary 205 is maximized, the data written to the slide dictionary is shifted by one entry, and a new integer part is added to the slide dictionary of the maximum entry. Data is to be written.

For example, assume that the slide dictionary 205 has entries 0 to 4, and integer part data is written in all entries. When writing to a new slide dictionary 205 in this state, the following is performed.
Shift the data of entry “1” to entry “0”.
Shift the data of entry “2” to entry “1”.
The data of entry “3” is shifted to entry “2”.
The data of entry “4” is shifted to entry “3”.
Write new integer part data to entry “4”.

  Here, it has been described that the integer part data that is not in the slide dictionary 205 is output as it is, but in this case, a code for identifying the compressed integer part data and the uncompressed integer part data is required. Here, “5” (non-existing entry) is used as the identification code of the uncompressed integer part data. A continuous number of codes is used as the entry identification code. That is, in the above example, since “D” is followed by “5”, it is possible to identify the next uncompressed integer data, “0”, “−1” after “E”. “Can identify that the integer data of the entry“ 0 ”is one and the next compressed data is an entry.

<Configuration of Color Separation Processing Unit 110>
Next, the color separation processing unit 110 will be described in detail with reference to FIG. As illustrated in FIG. 4, the color separation processing unit 110 includes a reference point reading unit 401, an expansion unit 405, a grid point data selection unit 407, a weight coefficient calculation unit 409, and an interpolation calculation unit 411.

  The reference point reading unit 401 reads the integer part compressed data stored in the print buffer 103, processes the integer part compressed data according to a flowchart (described later) in FIG. Retrieve and output data.

  The decompression unit 405 reads the decimal part compressed data stored in the print buffer 113 and determines whether or not the decimal part compressed data is compressed. If the decimal part compressed data is compressed, the decimal part compressed data is expanded, and data (hereinafter referred to as decimal part data) is output to the lattice point data selection unit 407 and the weighting factor calculation unit 409.

  The grid point data selection unit 407 uses the decimal part data output from the decompression unit 405 to use the grid point data (hereinafter referred to as an interpolation grid) necessary for the interpolation operation in the grid point data output from the reference point reading unit 401. (Referred to as point data) is selected and output to the interpolation calculation unit 411.

  A weighting coefficient calculation unit 409 calculates a weighting coefficient from the decimal part data. The interpolation calculation unit 411 performs interpolation processing based on the weighting factor calculated by the weighting factor calculation unit 409 and the grid point data for interpolation selected by the grid point data selection unit 407, and outputs color separation processing data. .

<Processing Flow in Color Separation Processing Unit 110>
Next, a processing flow in the color separation processing unit 110 will be described with reference to FIG. FIG. 5 is a diagram showing the flow of processing in the color separation processing unit 110 that processes integer-part compressed data read from the print buffer 103.

  In step S501, it is determined whether or not the integer part compressed data read from the print buffer 103 is compressed integer part data. If it is determined in step S501 that the data is not compressed integer part data, the process advances to step S502 to generate an address for accessing the color separation processing LUT 111 from the integer part compressed data.

  In step S503, grid point data is extracted from the color separation processing LUT 111 based on the generated address and output. Further, the grid point data is stored in the slide dictionary 403.

  On the other hand, if it is determined in step S501 that the integer part data is compressed, the process proceeds to step S504. In step S504, grid point data is extracted from the entry number of the slide dictionary 403 indicated by the integer part compressed data, and integer part data is output for the number of times the integer part compressed data is input at the next timing.

<Specific Example of Processing in Color Separation Processing Unit 110>
Next, a specific example of processing in the color separation processing unit 110 will be described with reference to FIG. Here, a case where the integer part compressed data is read by the reference point reading unit 401 in the order of “A”, “0”, “3”, “B” will be described as an example (the alphabet is an uncompressed integer part). Data, numbers indicate the integer data that is compressed).

  First, when “A” is read, “A” is determined to be uncompressed integer data (“No” in step S501), and “A” is used to access each grid point data of the color separation processing LUT 111. An address is generated (step S502). Based on the generated address, grid point data is extracted from the color separation processing LUT 111 and output to the grid point data selection unit 407. Further, the lattice point data is written in the entry “0” of the slide dictionary 403 (step S503). It should be noted that the generation of an address for accessing each grid point data of the color separation processing LUT 111 is performed by adding an offset value to “A”.

  Next, when the integer part compressed data “0” is read, it is determined that the integer part compressed data “0” has already been written in the slide dictionary 403 because it is compressed (“Yes” in step S501). As a result, the grid point data indicated by the entry “0” is extracted from the slide dictionary 403. Then, the grid point data is repeatedly output to the grid point data selection unit 407 by the number of the next integer part compressed data “3” (step S504).

  Next, when “B” is read out, lattice point data is extracted from the color separation processing LUT 111 and output to the lattice point data selection unit 407 in the same manner as when “A” is read out. Then, the grid point data is written in the entry “1” of the slide dictionary 403 (step S501 → 502 → 503).

  As described above, the grid point data is output to the grid point data selection unit 407.

  It is assumed that the number of grid point data extracted from the slide dictionary 403 or the color separation processing LUT 111 is determined by an interpolation method in color separation. For example, in the case of a four-point interpolation method, four grid point data are extracted. Further, in the case of the tetrahedral interpolation method, eight lattice point data are extracted.

  The behavior of the slide dictionary 403 is the same as that of the slide dictionary 205 described above. Furthermore, the number of entries in the slide dictionary 403 is the same as or more than the number of entries in the slide dictionary 205. However, the shift timing of entries in the slide dictionary 403 must be the same as that of the slide dictionary 205 regardless of the number of entries. Thereby, even if the entry of the data in the slide dictionary 205 is shifted by writing new data, the grid point data can be extracted from the slide dictionary 403 without any problem.

  Also, by having more entries in the slide dictionary 403 than the slide dictionary 205, it becomes possible to pre-read the slide dictionary, and even if there is a penalty due to a miss in the subsequent processing unit, the penalty is concealed and the real-time property is maintained. can do.

  As is clear from the above description, in the present embodiment, when arranging a print buffer for absorbing a variation in processing time due to a decrease in hit rate in color space conversion processing using a cache mechanism, The separation / compression unit 114 is arranged. As a result, the compressed PD-RGB data is stored in the print buffer, and the capacity of the print buffer can be suppressed.

[Other Embodiments]
Note that the present invention can be applied to a system (for example, a copier, a facsimile machine, etc.) consisting of a single device even if it is applied to a system composed of a plurality of devices (for example, a host computer, interface device, reader, printer, etc.). You may apply.

  Needless to say, the object of the present invention can also be achieved by supplying a system or apparatus with a storage medium storing software program codes for realizing the functions of the above-described embodiments. In this case, the above functions are realized by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium. In this case, the storage medium storing the program code constitutes the present invention.

  As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. be able to.

  Further, the present invention is not limited to the case where the functions of the above-described embodiments are realized by executing the program code read by the computer. For example, an OS (operating system) running on a computer performs part or all of actual processing based on an instruction of the program code, and the functions of the above-described embodiments may be realized by the processing. Needless to say, it is included.

  Furthermore, after the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the functions of the above-described embodiments are realized. Is also included. That is, after the program code is written in the memory, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing based on the instruction of the program code, and is realized by the processing. This is also included.

1 is a diagram illustrating a functional configuration of a printing apparatus including an image processing apparatus according to a first embodiment of the present invention. It is a figure which shows the detail of a data separation compression part. It is a figure which shows the flow of a process in the compression part which processes the integer part data output from the data separation part. It is a figure which shows the detail of a color separation process part. It is a figure which shows the flow of a process in the color separation process part which processes the integer part compression data read from the print buffer.

Claims (8)

An image processing apparatus comprising: a first processing unit that performs color space conversion processing on image data; and a second processing unit that performs color separation on the image data subjected to the color space conversion processing using an LUT.
Separation means for separating first data for extracting the lattice point data of the LUT from the image data subjected to the color space conversion processing;
Compression means for compressing the separated first data using a slide dictionary;
Storing means for storing the compressed first data,
The second processing means uses the LUT after reading the compressed first data from the storage means and generating first data for extracting the grid point data using a slide dictionary. An image processing apparatus that performs color separation. 2. The separation unit according to claim 1, wherein the separation unit separates first data for extracting grid point data of the LUT by extracting high-order bit data of the image data subjected to the color space conversion processing. The image processing apparatus described. The compression means uses the number of consecutive cases where the same value among the values constituting the separated first data continues and the entry of the slide dictionary to use the separated first data. The image processing apparatus according to claim 1, wherein the image processing apparatus is compressed. The separating means further separates second data for generating an interpolation coefficient for interpolating the grid point data extracted by the second processing means from the image data subjected to the color space conversion processing. The image processing apparatus according to claim 1, wherein: The image processing apparatus according to claim 4, wherein the second processing unit performs the color separation using an interpolation coefficient generated based on the second data. 2. The image processing apparatus according to claim 1, wherein the number of entries in the slide dictionary used in the second processing unit is larger than the number of entries in the slide dictionary used in the compression unit. An image processing method comprising: a first processing step for color space conversion processing of image data; and a second processing step for color separation of the image data subjected to the color space conversion processing using an LUT,
A separation step of separating first data for extracting grid point data of the LUT from the image data subjected to the color space conversion processing;
A compression step of compressing the separated first data using a slide dictionary;
A storage step of storing the compressed first data in a storage means,
The second processing step uses the LUT after reading the compressed first data from the storage means and generating first data for extracting the grid point data using a slide dictionary. An image processing method characterized by performing color separation. A control program for realizing the image processing method according to claim 7 by a computer.

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