JP2013038726A - Image processor - Google Patents

Abstract

When associating a color conversion profile with image data, the data size of the color conversion profile is reduced while suppressing a decrease in reproducibility of the image data.
An image processing apparatus that outputs generated image data and a color conversion profile suitable for an image data generation unit in association with each other. The color conversion profile represents data in which a plurality of sets of values in the second color space are arranged in a predetermined order based on the positions of a plurality of grid points in the first color space. The first grid point, which is a plurality of grid points, and the second grid point after the order of the first grid point represent colors that cannot be expressed by the image data generation unit, There are no other grid points representing colors that can be expressed by the image data generation unit between the second grid points. In the color conversion profile, the first set of values corresponding to the first grid point and the second set of values corresponding to the second grid point are the same value, and at least the first set of values and the second set of values. And it is compressed.
[Selection] Figure 4

Description

  The present invention relates to a color conversion profile associated with image data.

  A technique for associating image data with a color conversion profile (for example, an ICC profile) is known in order to appropriately reproduce image data representing photographs, characters, and the like on other devices (for example, a printer and a display) ( For example, PDF / A). In this color conversion profile, the color values of the color space (device-dependent color space) depending on the device (for example, scanner, digital camera, etc.) that generated the image data are set to other color spaces (for example, device-independent colors). For example, the correspondence between the color values in the device-dependent color space and the color values in other color spaces is described (see Patent Document 1).

JP 2007-124242 A JP 2008-31117 A JP 2006-94162 A

  However, if the image data is to be reproduced with high accuracy by another image processing apparatus, there is a problem that the data size of the color conversion profile associated with the image data increases.

  An object of the present invention is to provide a technique for reducing the data size of a color conversion profile while suppressing a decrease in reproducibility of the image data when a color conversion profile is associated with the image data.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application example]
An image processing apparatus,
An image data generation unit for generating image data;
An output unit that associates and outputs the generated image data and a color conversion profile suitable for the image data generation unit;
With
The color conversion profile is data in which a plurality of sets of values in a second color space are arranged in a predetermined order based on positions of a plurality of grid points in the first color space depending on the image data generation unit. Represents
The plurality of grid points include a first grid point and a second grid point whose order is later than the order of the first grid point;
The first grid point and the second grid point represent colors that cannot be expressed by the image data generation unit,
Between the first grid point and the second grid point, there is no other grid point representing a color that can be expressed by the image data generation unit,
In the color conversion profile, the first set of values corresponding to the first grid points and the second set of values corresponding to the second grid points are the same value,
In the color conversion profile, at least the first set of values corresponding to the first grid point and the second set of values corresponding to the second grid point are compressed.

  In the above configuration, in the color conversion profile output in association with the image data, the first set of values and the second values corresponding to the first and second grid points representing colors that cannot be expressed by the image data generation unit. The tuple values are the same and are compressed. For this reason, it is possible to reduce the data size of the color conversion profile while suppressing a decrease in reproducibility of the image data.

  The present invention can be realized in various forms, and can be realized in an apparatus form such as an image data generation apparatus or an image processing system in addition to an image processing apparatus. In addition to the color conversion profile creation method, it can be realized in various method forms such as an image processing method and a data processing method. Further, the present invention can be realized in the form of a computer program for realizing a color conversion profile creation method, a recording medium on which the computer program is recorded, and the like.

It is a block diagram which shows the structure of the image processing system in 1st Example. It is a figure explaining an ICC profile. It is a figure for demonstrating the order of each grid point prescribed | regulated in the scanner RGB color space SCP. 6 is a flowchart illustrating processing performed by the image processing system 1000. It is a flowchart which shows a profile correction process. It is a figure explaining a classification area. It is a figure for demonstrating the relationship between the color conversion table IHT and a use determination flag. It is a figure for demonstrating distribution of the sample value SV contained in the edit data HSD in the scanner RGB color space SCP. It is a figure explaining the lattice point REVx in 2nd Example.

A. First embodiment:
A-1. Configuration of Image Processing System 1000 FIG. 1 is a block diagram showing a configuration of an image processing system in the first embodiment. The image processing system 1000 includes a server 100 as a color conversion table generation device, a multifunction peripheral (peripheral device) 200 as a client, and a computer 300. The server 100 and the multifunction device 200 are communicably connected via a LAN (Local Area Network) 500 and the Internet 700. The multifunction device 200 and the computer 300 are connected via a LAN 500 so that they can communicate with each other.

  The server 100 includes a CPU 110, a storage device 140 such as an internal storage device (eg, ROM, RAM) or an external storage device (eg, hard disk drive), and a communication unit 130 including an interface for connecting to a network such as the Internet 700. And. The storage device 140 includes a profile storage unit 142. The storage device 140 stores a computer program (not shown) that causes the CPU 110 to realize each function. The computer program can be provided in a form recorded on a computer-readable recording medium. This recording medium includes a removable recording medium such as a CD-ROM or USB storage, an internal storage device of a computer such as ROM or RAM, and an external storage device connected to the computer such as a hard disk drive.

  The CPU 110 can control the entire server 100 by executing a computer program, and functions as an acquisition unit N10, a profile generation unit N20, and an output unit N30. Processing performed by each of these functional units N10 to N30 will be described later.

  The multifunction device 200 includes a CPU 210, a storage device 240 such as an internal storage device or an external storage device, a communication unit 250 including an interface for connecting to a network, an operation unit 260 including an operation panel and various buttons, and an inkjet. A printer unit 270 of a type and a scanner unit 280 of a flat bed type.

  The printer unit 270 prints an image by forming dots on a print medium using cyan (C), magenta (M), yellow (Y), and black (K) inks.

  The scanner unit 280 includes a platen glass 20 on which a document is placed and a CIS (Contact Image Sensor) type image sensor 10. The image sensor 10 includes a plurality of photoelectric conversion elements 11 such as CMOS, a lens 12, and a light source 13 including light emitting diodes (LEDs) of red, green, and blue colors. The plurality of photoelectric conversion elements 11 are arranged in a line in the main scanning direction. The main scanning direction is a direction perpendicular to the sub-scanning direction (FIG. 1) and parallel to the surface of the platen glass 20 on which the document is placed (a direction from the front to the back in FIG. 1).

  The image sensor 10 is configured to reciprocate (sub-scan) along the sub-scanning direction (FIG. 1) with the power of a step motor (not shown). The image sensor 10 turns on the light source 13 while performing sub-scanning from one end to the other end of the document, and outputs the intensity of reflected light from the document as an electrical signal using the photoelectric conversion element 11. At this time, in the light source 13, red, green, and blue LEDs are sequentially controlled to be lit. When these three color LEDs are turned on once, an electrical signal corresponding to the scanner RGB value of pixels for one line along the main scanning direction is output. The scanner unit 280 generates image data in which pixel data is represented by scanner RGB values based on the electrical signal output from the image sensor 10. The generated image data is also called scan data. Here, the scanner RGB values are color values in the scanner RGB color space that depend on the characteristics unique to the scanner unit 280 such as the characteristics of the LED of the light source 13 and the photoelectric conversion element 11.

  The storage device 240 includes a profile storage unit 242, a PDF / A file storage unit 244, and a test image data storage 246. The profile storage unit 242 stores the ICC profile. Hereinafter, the ICC profile is also simply referred to as a profile. The ICC profile stored in the profile storage unit 242 is an ICC profile that serves as a reference during profile correction processing described later, and is also referred to as a reference profile. A PDF / A file is stored in the PDF / A file storage unit 244. The test image data storage 246 stores test image data TSD and edit data HSD obtained by editing the test image data TSD. The test image data TSD and edit data HSD will be described later. The storage device 240 also includes a program storage unit (not shown) that stores various programs and data. These programs and data can be provided in a form recorded on a computer-readable recording medium.

  The PDF / A file is a file format conforming to ISO 190005 in the International Organization for Standardization (ISO), and is a file in which a profile is attached to one or more page data represented in the PDF format. In this case, the profile is inserted, for example, in the header or footer portion of the page data.

  The CPU 210 can control the entire MFP 200 by executing a program stored in the storage device 240, and includes a test image data generation unit M5, an acquisition unit M10, a storage processing unit M20, and a PDF / A. It functions as a file generation unit M30, an output unit M40, and a profile generation unit M45. The test image data generation unit M5 generates test image data and edit data HSD. The acquisition unit M10 acquires a new profile generated by the server 100. The storage processing unit M20 stores the new profile in the profile storage unit 242 as a new reference profile. The PDF / A file generation unit M30 generates a PDF / A file. The output unit M40 outputs the test image data stored in the test image data storage 246 to the server 100, or outputs the PDF / A file stored in the PDF / A file storage unit 244 to an external device (the computer 300 or the server 100). Output to. Details of the functional units of the CPU 210 will be described later in profile update processing or PDF / A file output processing.

  The computer 300 includes a CPU 310 and a storage device 340. The CPU 310 functions as a test image data generation unit L5, an acquisition unit L10, a storage processing unit L20, a PDF / A file generation unit L30, an output unit L40, and a profile generation unit L45. The storage device 340 includes a profile storage unit 342, a PDF / A file storage unit 344, and a test image data storage 346.

  FIG. 2 is a diagram for explaining the ICC profile. The profile includes a color conversion table IHT, an input table (not shown), and an output table (not shown). The color conversion table IHT is a table for converting scanner RGB values into Lab values. The Lab value is a color value in the CIELAB color space (L * a * b * color space) which is a device independent color space. The input table is a table for correcting scanner RGB values input to the color conversion table IHT. The output table is a table for correcting the Lab value output from the color conversion table IHT. The input table and the output table are normally set so that the input value and the output value are the same, but the output value for the input value is changed as necessary.

  FIG. 2A conceptually shows the color conversion table IHT. FIG. 2B shows the scanner RGB color space SCP. The color conversion table IHT is a Lab value associated with each of the P scanner RGB values of numbers 1 to P (P is an integer), and a Lab representing the color represented by each scanner RGB value in the CIELAB color space. It is a table which shows a value. In FIG. 2A, for convenience of explanation, scanner RGB values corresponding to each Lab value of the color conversion table IHT are shown in parallel with the color conversion table IHT. The scanner RGB values are not described. In the present embodiment, each value of red (R), green (G), and blue (B) in the scanner RGB values is represented by 8 bits (256 gradations). In the scanner RGB color space SCP, the R (red) axis, G (green) axis, and B (blue) axis are defined as shown in FIG.

  In the scanner RGB color space SCP, specific values of a predetermined number q (also referred to as grid number q) arranged at substantially equal intervals are set to R, G, and B values of 0 to 255. The P scanner RGB values associated with each Lab value of the color conversion table IHT correspond to any one of the specific values of the grid number q. In this embodiment, the number of grids q is 17. In this case, the 17 specific values are 16 values represented by 16 × r (r is an integer of 0 ≦ r ≦ 15) and 255. Therefore, the total number P of scanner RGB values in the color conversion table IHT is 4913. These 4913 points are also referred to as lattice points REV.

  In FIG. 2B, the grid points REV are arranged in a substantially equidistant grid pattern in a color gamut represented by a cube when the scanner RGB color space SCP is expressed in a three-dimensional orthogonal coordinate system. Hereinafter, individual grid points REV may be represented using specific value numbers (0, 1, 2,..., 16) assigned to 17 specific values in ascending order. For example, the grid point REV positioned at the coordinates (0, 0, 0) in the scanner RGB color space SCP has an R component value (component in the R axis direction), a G component value (component in the G axis direction), and a B component value. A grid point REV (0, 0, 0) is displayed using a specific value number corresponding to (component in the B-axis direction). Similarly, a lattice point REV located at coordinates (255, 0, 0) is displayed as a lattice point REV (16, 0, 0), and a lattice point REV located at coordinates (0, 255, 0) is represented by a lattice point REV. The point REV (0, 16, 0) is displayed. In FIG. 2B, point K (coordinate (0, 0, 0) position) is a black point in the scanner RGB color space SCP. Point W (the position of coordinates (255, 255, 255)) is a white point in the scanner RGB color space SCP. As shown in FIG. 2B, a dashed line GL connecting the K point and the W point is an achromatic axis in the scanner RGB color space SCP. The one-dot broken line GL is also called an achromatic color axis GL.

In the color conversion table IHT, as shown in FIG. 2A, corresponding Lab values are arranged according to a predetermined order of the plurality of grid points REV. As a result, a computer that uses the color conversion table IHT (for example, the CPU 210 of the multifunction device 200) can perform color conversion even if the color conversion table IHT does not include information representing grid points (that is, scanner RGB values). A grid point corresponding to each Lab value included in the table IHT can be specified. Hereinafter, the order of the plurality of grid points REV will be described.
SQ (0 ≦ SQ <total number of grid points) representing the order of the grid points REV (V, W, X) is expressed by the following formula (1) using the grid number q described above.
SQ = {q × q × V + q × W + X} (1)

  FIG. 3 is a diagram for explaining the order of each grid point defined in the scanner RGB color space SCP. FIG. 3A is a diagram showing a plurality of planes passing through the scanner RGB color space SCP. Here, in order to explain the order of each grid point, 17 planes hm parallel to the B axis and the G axis are defined in the scanner RGB color space SCP. Specifically, a plane hm passing through the lattice point REV (V, 0, 0) (V is an integer of 0 to 16) is defined as a plane hmV. For example, a plane hm passing through the grid point REV (0, 0, 0) is defined as a plane hm0, and a plane hm passing through the grid point REV (1, 0, 0) is defined as a plane hm1. Among the grid points REV arranged on each of the 17 planes hmV, the order of the grid points REV arranged on the plane hm0 is the first, and the order of the grid points REV arranged on the plane hm16 is the last. . The R component values of the plurality of lattice points included in the same plane hmV are the same value.

  FIG. 3B is a diagram when the plane hm0 is viewed from the R-axis direction. In each plane hm, 17 arrows ysW (W is an integer of 0 to 16) are defined. The arrow ysW passes through the plane hmV and is parallel to the B axis, and is arranged on the lattice point REV whose specific value number corresponding to the G component value is W. For example, the arrow ys0 on the plane hm0 passes through the lattice points REV (0, 0, 0), REV (0, 0, 1), ..., REV (0, 0, 16) (FIG. 3B). ). Among the lattice points REV disposed on each of the 17 arrows ysW disposed on the same plane hmV, the order of the lattice points REV disposed on the first arrow ys0 is the first, and the 17th arrow The order of the grid points REV arranged at ys16 is the latest. Here, 17 lattice points REV arranged on one arrow ysW are referred to as a lattice point group kgW. The 17 lattice points REV included in one lattice point group kgW have the same R component value, the same G component value, and different B component values.

  From the above, when two lattice point groups (each including 17 lattice point groups kgW, also referred to as planar lattice point groups) arranged on different planes hmV are compared, the smaller the R component value of the lattice point REV is, The order of the planar lattice point group is first, and the larger the R component value, the later the order of the planar lattice point group. Comparing two lattice point groups kgW arranged on the same plane hmV, the smaller the G component value of the lattice point REV, the earlier the order of the lattice point group kgW, and the larger the G component value, The order of group kgW is later. Comparing 17 grid points REV included in one grid point group kgW, the order of the grid points REV is earlier as the B component value is smaller, and the order of the grid points REV is later as the B component value is larger. It is.

  The color conversion table IHT included in the reference profile is created by, for example, a known method by the manufacturer of the multifunction device 200. For example, the creator obtains scan data by reading a color chart printed using the printer unit 270 using the scanner unit 280. On the other hand, the color chart is measured with a predetermined colorimeter to obtain colorimetric data. As a result, the creator acquires correspondence data in which the scanner RGB values included in the scan data are associated with the Lab values included in the colorimetric data. The creator creates the color conversion table IHT included in the reference profile based on the correspondence data. Note that the computer can specify the grid number q using the total number P of Lab values included in the color conversion table IHT (for example, if the total number T of Lab values is 4913, the number of grids q is 17). ).

A-2. Processing by the image processing system 1000:
The image processing system 1000 implements profile update processing and new profile creation processing for correcting a reference profile and generating a correction profile (new profile). Further, the image processing system 1000 realizes a PDF / A file output process for outputting the new profile generated by the profile update process and the new profile creation process in association with the generated image data. FIG. 4 is a flowchart showing processing performed by the image processing system 1000. Specifically, FIG. 4A is a flowchart showing processing steps of profile update processing and new profile creation processing. FIG. 4B is a flowchart showing the processing steps of the PDF / A file output processing. Hereinafter, first, the profile update process and the new profile creation process will be described, and then the PDF / A file output process will be described.

A-2-1. Profile update process and new profile creation process:
The profile update process is a process in which the MFP 200 or the computer 300 uses the server 100 to update the reference profile. Hereinafter, the multifunction device 200 or the computer 300 is also simply referred to as a client. The new profile creation process is a process in which the server 100 creates a new profile in response to a request from the client. Hereinafter, a case where the multifunction device 200 is a client will be described as an example.

  For example, when the MFP 200 as a client receives an instruction to update the reference profile from the user via the operation unit 260, the MFP 200 starts the profile update process.

  The test image data generation unit M5 generates test image data TSD (step S110). Specifically, the test image data generation unit M5 displays, for example, a message prompting the user to set the color chart 400a as a document on the scanner unit 280 on the operation panel of the operation unit 260. The scanner unit 280 scans the color chart 400a as shown in FIG. 1 and generates image data of the color chart 400a (RAW data format image data before being converted into JPEG format, etc.) as test image data TSD. To do.

  The color chart 400a of this embodiment includes 4913 different color patches representing 4913 different colors distributed over the entire color gamut of an sRGB (standard RGB) color space, which is a standard color space used in monitors and the like. 410a. Specifically, the 4913 color patches 410a have R (red), G (Green), and B (blue) values in the sRGB (standard RGB) color space, and the 4913 scanner RGB values described above. This corresponds to 4913 kinds of color values obtained by setting the same value as the grid point REV. The color chart 400a is created by printing image data representing the colors of 4913 color patches 410a in the sRGB (standard RGB) color space using a predetermined printer. The color chart 400a can be provided as an accessory when the user purchases the multifunction device 200. The colors of the plurality of color patches 410a are preferably selected so as to approximate all colors assumed to be included in the document read by the scanner unit 280 and to be distributed over the entire color gamut of a predetermined color space. . In this way, whether each grid point of the color conversion table IHT is a grid point related to a color in a range that cannot be expressed by the scanner unit 280 or a grid point related to a color in a range that can be expressed by the scanner unit 280 is appropriately determined. Can be judged.

  The test image data generation unit M5 generates edit data HSD using the pixel values (scanner RGB values) of the test image data TSD based on the test image data TSD (step S115). As shown in FIG. 1, the edit data HSD is 4913 scanner RGB values representing the colors of the 4913 color patches 410a of the color chart 400a. These scanner RGB values are also referred to as sample values SV below.

  The output unit M40 transmits the editing data HSD generated by the test image data generation unit M5 and the reference profile stored in the profile storage unit 242 to the server 100 (step S120). Note that the output unit M40 may transmit the test image data TSD as it is to the server 100 and generate the editing data HSD on the server 100 side.

  The acquisition unit N10 of the server 100 acquires the edit data HSD and the reference profile transmitted from the multifunction device 200 (steps S200 and S210). When the acquisition unit N10 of the server 100 acquires these data, a new profile creation process is started. Note that the MFP 200 serving as a client suspends the profile update process and stands by while the server 100 is executing the new profile creation process.

  Subsequently, the profile generation unit N20 executes profile correction processing (step S220). In this profile correction process, a classification area, which will be described later, is set, the classification area to which each pixel of the editing data HSD belongs is specified, and based on this classification result, a grid relating to a color that is not used in the editing data HSD A point (also called a grid point to be changed) is determined. Next, the Lab value corresponding to the grid point to be changed in the reference profile is changed, and a correction profile is generated. Subsequently, a compressed profile is generated based on the correction profile. This will be specifically described below.

  FIG. 5 is a flowchart showing the profile correction process in S220 of FIG. In step S500, first, the profile generation unit N20 sets a classification area.

  FIG. 6 is a diagram for explaining the classification region. The profile generation unit N20 includes 4096 classification regions CA (x, y, z) (x is an integer in the range of 0 ≦ x ≦ 15, y is an integer in the range of 0 ≦ y ≦ 15, and z is 0 ≦ z ≦ 15 (integer). Each classification area CA (x, y, z) has a cubic shape having eight lattice points REV as vertices. The eight lattice points REV constituting the classification area CA (x, y, z) are REV (x, y, z), REV (x + 1, y, z), REV (z, y + 1, z), REV (x , Y, z + 1), REV (x + 1, y + 1, z), REV (x, y + 1, z + 1), REV (x + 1, y, z + 1), REV (x + 1, y + 1, z + 1). In FIG. 6, only eight classification regions (x, y, z) in the ranges of 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ z ≦ 1 are illustrated in order to avoid the complexity of the drawing. Actually, 4096 (16 × 16 × 16) without gaps in the cubic range of 0 ≦ R ≦ 255, 0 ≦ G ≦ 255, 0 ≦ B ≦ 255 in the scanner RGB color space SCP shown in FIG. Classification area CA (x, y, z) is set. The classification area CA (x, y, z) is also simply referred to as a classification area CA.

  In this embodiment, all sample values SV (scanner RGB values) included in the edit data HSD are classified. The profile generation unit N20 selects one sample value SV included in the editing data HSD as a processing target (step S510).

  The profile generation unit N20 specifies whether the sample value SV to be processed belongs to any one of the 4096 classification areas CA described above (step S515). Further, the profile generation unit N20 specifies eight lattice points REV that form the specified classification area CA (step S520). In the reference profile (color conversion table IHT), the Lab value associated with the grid point REV specified in this step may be used when performing color conversion of the scanner RGB value that can be acquired by the scanner unit 280. It is thought that there is.

  FIG. 7 is a diagram for explaining the relationship between the color conversion table IHT and the use determination flag. The color conversion table IHT is associated with a flag value representing a usage determination flag. Specifically, one Lab determination value in the color conversion table IHT is associated with one flag value of the usage determination flag. . The profile generation unit N20 assumes that the eight grid points REV identified in step 520 are grid points related to scanner RGB values (colors that can be expressed by the scanner unit 280) that can be acquired by the scanner unit 280, and are not subject to change. (Step S525). In this case, the profile generation unit N20 sets the flag value of the Lab value corresponding to the lattice point determined not to be changed to “1”, and turns on the use determination flag.

  The profile generation unit N20 returns to the process of step S510 when the processes of steps S510 to S525 are not executed for all the sample values SV included in the edit data HSD (step S530: No). When the profile generation unit N20 determines that the processing of steps S510 to S525 has been executed for all the sample values SV included in the editing data HSD (step S530: Yes), the profile generation unit N20 performs the following processing. That is, the profile generation unit N20 causes the scanner unit 280 to display grid points REV (for example, FIG. 7A: grid points Nos. 7 to 12) for which the use determination flag is off (that is, the flag value is 0). It is determined as a grid point to be changed as a grid point related to a scanner RGB value (a color within a range that cannot be expressed by the scanner unit 280) that is not acquired (step S535).

  As shown in FIG. 7B, the profile generation unit N20 changes the Lab value corresponding to the grid point to be changed in the reference profile (color conversion table IHT), and generates the correction color conversion table IHTs (step S540). ). The entire correction color conversion table IHTs, input table, and output table are also referred to as a correction profile. Specifically, the profile generation unit N20 searches for and changes the Lab value corresponding to the grid point REV to be changed (that is, the Lab value for which the use determination flag is off) in order from the top of the color conversion table IHT. When the Lab value corresponding to the target grid point REV is found, the Lab value is changed to the same value as the Lab value corresponding to the grid point REV that is not the target of change in order immediately before the change target grid point REV. . Subsequently, if the grid point REV in the next order is also the grid point REV to be changed, the profile generation unit N20 changes the Lab value corresponding to the grid point REV to be changed to the previous Lab value. Change to the same value as after the change. As described above, if the grid points REV to be changed are consecutive, the profile generation unit N20 corresponds the Lab value corresponding to each successive grid point REV to the grid point REV that is not the nearest change target in the previous order. Change to the same value as the Lab value. For example, the profile generation unit N20 searches for the Lab value corresponding to the grid point to be changed (that is, the Lab value for which the use determination flag is off) in order from the top of the color conversion table IHT shown in FIG. To do. When the profile generation unit N20 determines that the Lab value corresponding to the grid point of No. 7 is the Lab value corresponding to the grid point to be changed, as illustrated in FIG. The Lab value corresponding to No. 6 is changed to the same value as the Lab value corresponding to the grid point No. 6. And since the use determination flag corresponding to the grid points of No. 8 to No. 12 following the No. 7 grid point is OFF in the profile generation unit N20 (FIG. 7A), No. 8 The Lab values corresponding to the grid points No. 12 to No. 12 are also determined to be Lab values corresponding to the grid points to be changed, and changed to the Lab values corresponding to the grid points No. 6 (FIG. 7). (B)).

  FIG. 8 is a diagram for explaining a distribution of scanner RGB values (sample values SV included in the editing data HSD) included in the test image data in the scanner RGB color space SCP. As shown in FIG. 8, in the scanner RGB color space SCP, there is an area RYI that cannot be expressed by the scanner unit 280 (also referred to as an unexpressable area). Such a lattice point REV in the unrepresentable region RYI can be specified as the lattice point to be changed. In FIG. 8, a part of the unrepresentable area RYI is shown in the scanner RGB color space SCP.

  In step 545 of FIG. 5, the profile generation unit N20 deflate-compresses the correction profile (correction color conversion table IHTs) to generate a compressed correction profile. For example, when there is data in txt format (original data) including a character string of [AAAAAA] with six consecutive characters A, when the original data is Deflate-compressed, the compressed data is [A6] In this way, it is expressed by the letter A and its continuous number, and the data size is suppressed compared to the original data. This Deflate compression will be specifically described below.

  The profile generation unit N20 calculates the Lab value (L * 1, a * 1, b * 1) corresponding to the No. 1 grid point (first order) in the color conversion table IHT and the next No. 2 grid point. It is determined whether or not the Lab value corresponding to. If not matched, the profile generation unit N20 uses [0] (L * 1, a * 1) using the identification value [0] indicating that they do not match and the Lab value corresponding to the No. 1 grid point. , B * 1). The profile generation unit N20 determines that the Lab value (L * 1, a * 1, b * 1) corresponding to the No. 1 grid point matches the Lab value corresponding to the next No. 2 grid point. Search for each Lab value corresponding to the grid point in the order after No. 2 until the Lab value does not match the Lab value corresponding to the grid point No. 1 according to the order of the grid points. Continue. The profile generation unit N20, when U Lab values that match the Lab values corresponding to the No. 1 lattice point are found in succession, the identification value [1] indicating that they match, and No. 1 [1] (L * 1, a * 1, b * 1) <U> is described using the Lab value corresponding to the grid points and the continuously matching number U. The identification value is represented by 1 bit, and the continuously matching number U is represented by 8 bits, for example.

  That is, the profile generation unit N20 determines that the Lab value (L * s1, a * s1, b * s1) corresponding to the lattice point in the order s1 does not match the Lab value corresponding to the lattice point in the next order. [0] (L * s1, a * s1, b * 1). Further, the profile generation unit N20, when the U values that match the Lab values (L * s1, a * s1, b * s1) corresponding to the lattice points of the order s1 are found in succession, [1] (L * s1, a * s1, b * s1) <U>. For example, “(L * 1, a * 1, b * 1), (L * 2, a * 2, b * 2), (L * 2, a * 2, b * 2), (L * 2, If the four Lab values represented as “a * 2, b * 2)” are Deflate-compressed, [0] (L * 1, a * 1, b * 1) [1] (L * 2, a * 2, b * 2) It is described as <3>. In this case, since the L * value, a * value, and b * value of the Lab value are each represented by 8 bits, the data size of the four Lab values before compression is 12 (L * value, a * value, The total number of b * values) × 8 bits is 96 bits. On the other hand, the data size after compression is 58 bits with 2 (number of identification values) × 1 bit + 6 (total number of L * values, a * values, b * values) × 8 bits + 1 (number U) × 8 bits. . Thus, the data size after Deflate compression becomes smaller than the data size before compression as the Lab value having the same value continues.

  As described above, the correction color conversion table IHTs of the correction profile can be changed by the profile generation unit N20 to the same value with continuous Lab values. Accordingly, the compressed correction profile generated by deflate compression of the correction profile has a smaller data size than the compressed reference profile generated by deflate compression of the reference profile. In other words, among the grid points REV of the scanner RGB color space SCP, Lab values corresponding to the grid points REV related to the scanner RGB values (colors that can be expressed by the scanner unit 280) that can be acquired by the scanner unit 280 are compressed and corrected. It can be said that the data size of the profile is changed to be smaller than the data size of the compressed reference profile.

  In step S550 of FIG. 5, the profile generation unit N20 stores the generated compressed correction profile in the profile storage unit 142, and ends the profile correction processing shown in FIG.

  In S230 of FIG. 4A, the output unit N30 transmits the generated compressed correction profile as a new profile to the MFP 200 that is a client. The server 100 ends the new profile creation process after transmitting the new profile.

  The acquisition unit M10 of the MFP 200 acquires a new profile (compressed correction profile) transmitted from the server 100 (step S300). The profile update process is resumed when the acquisition unit M10 acquires a new profile.

  The storage processing unit M20 stores the new profile (compressed correction profile) in the profile storage unit 242 (step S305). In this case, the storage processing unit M20 deletes the reference profile that has already been stored in the profile storage unit 242.

A-2-1. PDF / A file output processing:
The PDF / A file output process (FIG. 4B) is a process in which the client that has performed the profile update process generates and outputs a PDF / A file based on an instruction from the user. Hereinafter, a case where the MFP 200 is a client that has performed profile update processing will be described as an example.

  When there is an instruction to generate image data from the user via the operation unit 260 (FIG. 4B: Step S307: Yes), the scanner unit 280 scans the document set by the user, and the image data Is generated (step S310). When there is no image data generation instruction (step S307: No), the scanner unit 280 ends the PDF / A file output process.

  The PDF / A file generation unit M30 compresses the image data generated by the scanner unit 280 into a predetermined format (for example, JPEG format), and generates PDF format page data using the compressed image data. Then, the PDF / A file generation unit M30 reads the new profile stored in the profile storage unit 242 in the profile update process, associates the new profile with page data, and generates a PDF / A file (step S320). ). The PDF / A file generation unit M30 stores the generated PDF / A file in the PDF / A file storage unit 244 (step S330).

  When there is an output request from an external device (for example, the computer 300) (step S340: Yes), the output unit M40 has requested to output a PDF / A file stored in the PDF / A file storage unit 244. The data is output to the external device (step S350), and the PDF / A file output process is terminated. When there is no output request from the client (step S340: No), the output unit M40 ends the PDF / A file output process.

  Note that the MFP 200 may perform the PDF / A file output process in parallel with the profile update process described above. Further, the MFP 200 does not transmit the edit data HSD and the reference profile to the server 100 in the profile update process, and performs the profile correction process (FIG. 4A: step S220) performed by the server 100 in the profile update process. You may make it produce | generate the production | generation part M45. The profile generation unit M45 has the same function as the profile generation unit N20 of the server 100.

  In addition, the functional units L5 to L40 of the computer 300 have the same functions as the functional units M5 to M40 having the same names provided in the multifunction machine 200, respectively. Therefore, the computer 300 may perform profile update processing and PDF / A file output processing as a client. In this case, the computer 300 causes the scanner unit 280 of the multifunction device 200 to read the color chart 400 a to generate the test image data TSD, and obtains the test image data TSD from the multifunction device 200.

  In the present embodiment, the new profile (compressed correction profile) corresponds to two or more grid points REV that are in sequential order and represent a grid point REV that indicates a color that cannot be expressed by the multifunction device 200 (scanner unit 280). The Lab value to be compressed is Deflate-compressed. As described above, the Lab value corresponding to the grid point REV indicating a color that cannot be expressed by the multifunction device 200 (scanner unit 280) is deflate-compressed, so that the new profile (compressed correction profile) is subjected to profile correction processing. The data size is smaller than the data size of the compressed reference profile obtained by performing Deflate compression on the reference profile before being performed. That is, when the new profile associated with the image data generated by the scanner unit 280 is used to reproduce the image data, the grid points indicating colors that cannot be expressed by the multifunction device 200 (scanner unit 280) in the new profile. Since the Lab value corresponding to REV is a compression target, it is possible to suppress a decrease in reproducibility in the image data, and to reduce the data size in the new profile.

  In this embodiment, in the profile correction process, when the profile generation unit N20 finds a grid point REV to be changed, the profile generation unit N20 sets one Lab value corresponding to the grid point REV to be changed to one more than the grid point REV to be changed. The value is changed to the same value as the Lab value corresponding to the grid point REV that is not the target to be changed in the previous order. Subsequently, if the grid point REV in the next order is also the grid point REV to be changed, the profile generation unit N20 changes the Lab value corresponding to the grid point REV to be changed to the previous Lab value. Change to the same value as after the change. That is, in the new profile (compressed correction profile), the Lab value corresponding to the grid point REV not to be changed, and the Lab value corresponding to each of two or more continuous grid points REV in the order following the grid point REV, Are the same value (FIG. 7B). In this way, the Lab value corresponding to the grid point REV not to be changed and the Lab value respectively corresponding to two or more consecutive grid points REV in the order following the grid point REV are compressed together. As a result, the data size of the new profile (compressed correction profile) can be reduced.

  In this embodiment, the color conversion table IHT includes a plurality of Lab values corresponding to the grid point group kg (W−1) (for example, the grid point group kg0, see FIG. 3) and the grid point group kgW (for example, the grid point group). A plurality of Lab values corresponding to the group kg1) are successively arranged in this order. In the profile correction process (FIG. 4B), when there are two lattice points that are change targets, and there is no lattice point REV that is not the change target between these two lattice points REV, The grid point REV that is the change target of the grid point group kg (W-1), and the other grid point REV that is the change target may be included in the grid point group kgW. As a result, in the profile correction process, the two sets of Lab values corresponding to two grid points that can be completely different colors in the scanner RGB color space SCP are changed to have the same value. For example, the REV (0, 16, 16) (FIG. 3A) of the grid point group kg16 on the plane hm0 is the grid point REV to be changed, and the four grid points REV of the grid point group kg0 on the plane hm1 ( (1, 0, 0) to (1, 0, 3) (FIG. 3A) can also be grid points REV to be changed. In this case, two sets of Lab values corresponding to two lattice points REV (lattice point REV (0, 16, 16) and lattice point REV (1, 0, 3)) that can be completely different colors due to different planes. It is changed so that it becomes the same value. Further, REV (0, 15, 15) to (0, 15, 16) (FIG. 3B) of the grid point group kg15 on the plane hm0 is the grid point REV to be changed, and the grid point group on the plane hm0. Four lattice points REV (0, 16, 0) to (0, 16, 3) (FIG. 3B) of kg16 can also be lattice points REV to be changed. In this case, two sets of Labs corresponding to two grid points REV (lattice point REV (0,15,15) and grid point REV (0,16,3)) that can be completely different colors by different grid point groups. It is changed so that the value becomes the same value.

  In the embodiment described above, a plurality of sample values SV (4913 in this embodiment) based on the pixel values (scanner RGB values) of the test image data TSD are used to represent a plurality of data that cannot be expressed by the multifunction device 200 (scanner unit 280). The grid points to be changed are specified. In this way, it is possible to appropriately specify a plurality of lattice points that are change targets that cannot be expressed by the multifunction device 200 (scanner unit 280).

  In this embodiment, the scanner unit 280 is an example of an image data generation unit. The new profile (compressed correction profile) stored in the profile storage unit 242 is an example of “color conversion profile suitable for the image data generation unit”. The grid points REV of No. 7 and No. 8 shown in FIG. 7 are examples of the first grid point and the second grid point, respectively, and the grid point REV of No. 6 shown in FIG. It is an example.

B. Second embodiment:
In the first embodiment, in the profile correction process (FIG. 5), test image data is analyzed, and lattice points that are not to be changed are determined based on the analysis result (see steps S525 to S535). In the second embodiment, in the scanner RGB color space SCP, there are lattice points REVx that are not to be changed (not changed) regardless of the analysis result of the test image data. The lattice point REVx is an example of a specific lattice point in the claims.

  FIG. 9 is a diagram illustrating the lattice point REVx in the second embodiment. FIG. 9A is a diagram showing lattice points REVx in the scanner RGB color space SCP. FIG. 9B is a diagram showing a correction color conversion table IHTs1 generated when the grid point REVx exists in the scanner RGB color space SCP in the profile correction process.

  As shown in FIG. 9A, in the present embodiment, the lattice point REVx is a predetermined lattice point in the scanner RGB color space SCP, and is included in the analysis result of the test image data in the profile correction process. Regardless of this, the grid points are not subject to change. The grid points REVx are arranged in a regular grid pattern in the scanner RGB color space SCP. In the example illustrated in FIG. 9A, the lattice point REVx includes REVx (0, 0, 0) along three axes (R axis, G axis, and B axis) among the 4913 lattice points REV described above. ) Are arranged at every four points on the basis of the lattice points.

  In the present embodiment, the lattice point REV is a 17 × 17 × 17 lattice point, and the lattice point REVx is a 5 × 5 × 5 lattice point.

  In the present embodiment, in the profile correction process, the profile generation unit N20 classifies the use determination flag of the Lab value corresponding to the lattice point REVx, and classifies the pixels of the edit data HSD (FIG. 5B: steps S510 to S530). Regardless of the result of), “1” is set. As a result, the profile generation unit N20 does not always change the Lab value corresponding to the lattice point REVx (see the correction color conversion table IHTs1: hatched portion in FIG. 9B). If the grid point REV in the next order of the grid point REVx is the grid point to be changed, the profile generation unit N20 sets the Lab value corresponding to the grid point REV to be changed to the previous grid point REVx. Change to the corresponding Lab value. The profile generation unit N20 changes the Lab value corresponding to the grid point REV to be changed to the Lab value that has been changed immediately before if the grid point REV in the next order is further the grid point REV to be changed. To do. Thus, if the grid points REV in the order after the grid point REVx are continuously grid points to be changed, the profile generating unit N20 calculates Lab values corresponding to the continuous grid points REV. The Lab value is changed to the Lab value corresponding to the nearest grid point REVx in the earlier order. In FIG. 9B, the Lab value corresponding to the grid points No. 10 to 12 as the change target is changed to the Lab value corresponding to the latest grid point REVx.

  According to the present embodiment, among the grid points REV in the scanner RGB color space SCP, the grid point REVx is determined as a grid point that is not to be changed regardless of the analysis result of the edit data HSD. As a result, regardless of the edit data HSD, the Lab value corresponding to the grid point REVx can be fixed to the Lab value associated with the reference profile (color conversion table). In other words, the Lab value corresponding to the grid point REVx in the new profile (reference profile) is set to a different value regardless of whether or not it represents a color that cannot be expressed by the multifunction device 200 (scanner unit 280). Accordingly, the PDF / A file including the new profile (compressed correction profile) generated by the profile correction process is changed from the multifunction device 200 to an external device capable of expressing colors that cannot be represented by the multifunction device 200 (scanner unit 280). When output, the external device can reproduce the image data included in the PDF / A file even for colors in a range that cannot be expressed by the MFP 200. As a result, the reproducibility of the image data associated with the new profile can be suppressed from being significantly reduced in the external device.

  Here, as a specific example in which the number of colors used increases, by editing a PDF / A file including page data, text data such as annotations and single-color graphic data such as arrows are included in the page data. In some cases, it may be added. Even in such a case, since the Lab value corresponding to the grid point REVx in the new profile is fixed to the Lab value associated in the reference profile (color conversion table), the edited page data The included text and graphics are appropriately reproduced by a specific device such as an external device as compared with the first embodiment.

  In the new profile (compressed correction profile) of the present embodiment, two or more continuous lattice points REV, each of which corresponds to a lattice point REV to be changed, and a Lab corresponding to a lattice point REVx. The value is the same value. In this way, the data size of the new profile can be reduced while making the Lab values corresponding to the lattice points REVx different from each other.

  The grid points REVx are not limited to 5 × 5 × 5 (125) grid points, but the grid points REV are N × N × N grid points, and the grid points REVx are M × M × M. N and M may be values satisfying (N−1) / (M−1) = k. Here, M, N, and K are integers that satisfy N> M ≧ 2, k ≧ 2. The grid points REVx have, for example, the same number (type) as the so-called WEB safe color (216 types of RGB values) defined in a general RGB color space in which each component value is represented by 256 gradations. Preferably they are arranged.

C. Variations:
The present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

(1) In the above embodiment, page data and a compressed correction profile generated using this page data are associated with each other to form one PDF / A file. Instead, the page data and the compressed correction profile generated using the page data are stored as separate files in the storage device 240, and the page data and the compressed correction profile are associated with each other by a file name or the like. May be. The file including the page data and the compressed correction profile is not limited to the PDF / A file, but may be another file format (for example, PDF file).

(2) In the above embodiment, a profile for converting the color values of the scanner RGB color space into the color values of the CIELAB color space (L * a * b * color space) is generated. It is not something that can be done. For example, the present invention may be applied to generation of a profile for converting a color value of a printer device-dependent RGB color space into a color value of a printer CMYK color space. Generally speaking, the present invention can be applied to creating a profile in which a plurality of sets of values in the second color space are associated with a plurality of grid points in the first color space.

(3) In the profile correction processing of each of the embodiments described above, the profile generation unit N20 sets the Lab value corresponding to the grid point REV to be changed to a grid that is in the order before the grid point REV to be changed and is not to be changed. The value is changed to the same value as the Lab value corresponding to the point REV. Instead of this, the profile generation unit N20 may change the Lab values corresponding to a plurality of grid points REV to be changed to the same value regardless of the Lab values corresponding to the grid points REV that are not the change target. good. For example, the profile generation unit N20 may change all Lab values (L *, a *, b *) corresponding to a plurality of grid points REV to be changed to (0, 0, 0). In addition, it is not necessary to make all Lab values (L *, a *, b *) corresponding to a plurality of grid points REV to be changed in the same order, for example, two values may be the same.

  In the above embodiment, Deflate compression is used for profile compression, but other compression methods may be used. In this case, in the profile correction processing of the above-described embodiment, the profile generation unit N20 changes the data so that the data size of the compressed correction profile is reduced when compression is performed using the employed compression method. The Lab value corresponding to the grid point REV may be changed. A system that can compress multiple consecutively different values, for example, a system that can compress consecutive values such as “1, 2, 3, 4, 5” as “1-5” In that case, the profile generation unit N20 may change the Lab values corresponding to the plurality of grid points REV to be changed in the order to different values that are regularly continued.

  Generally speaking, the profile generation unit N20 generates compression when two or more sets of Lab values corresponding to two or more grid points to be changed are compressed using a specific compression method. Preferably, the data size of the completed correction profile is changed so as to be smaller than the data size of the compressed reference profile generated when the reference profile is compressed by a specific compression method.

(4) In the profile correction process in the above-described embodiment, each classification area CA is set to a cubic shape having eight lattice points REV as vertices, but the present invention is not limited to this. For example, each classification area CA may be an area having the same size as the embodiment and centered on one grid point REV. In general, each classification area CA is preferably defined based on at least one or more grid points.

(5) In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced with hardware. Also good.

  DESCRIPTION OF SYMBOLS 100 ... Server, 110 ... CPU110, 130 ... Communication part, 140 ... Storage device, 200 ... Multi-function device, 210 ... CPU, 240 ... Storage device, 250 ... Communication unit, 260 ... operation unit, 280 ... scanner unit, 300 ... computer, 340 ... storage device, 1000 ... image processing system,

Claims (7)

An image processing apparatus,
An image data generation unit for generating image data;
An output unit that associates and outputs the generated image data and a color conversion profile suitable for the image data generation unit;
With
The color conversion profile is data in which a plurality of sets of values in a second color space are arranged in a predetermined order based on positions of a plurality of grid points in the first color space depending on the image data generation unit. Represents
The plurality of grid points include a first grid point and a second grid point whose order is later than the order of the first grid point;
The first grid point and the second grid point represent colors that cannot be expressed by the image data generation unit,
Between the first grid point and the second grid point, there is no other grid point representing a color that can be expressed by the image data generation unit,
In the color conversion profile, the first set of values corresponding to the first grid points and the second set of values corresponding to the second grid points are the same value,
In the color conversion profile, at least the first set of values corresponding to the first grid point and the second set of values corresponding to the second grid point are compressed. The image processing apparatus according to claim 1,
The plurality of grid points in the first color space are third grid points representing colors within a range that can be expressed by the image data generation unit, and the order of the third grid points is the first grid point. Including the third grid point that is ahead of
A third set of values in the second color space corresponding to the third grid point, the first set of values corresponding to the first grid point, and the second set corresponding to the second grid point. An image processing apparatus having the same value as The image processing apparatus according to claim 1, wherein:
The plurality of grid points in the first color space are:
A first grid point group in the first color space, wherein the first component values of the grid points belonging to the first grid point group are the same, the second component values are the same, and the third The first grid point group having different component values and the first component value of each grid point being a first value;
A second grid point group in the first color space, the first component values of the grid points belonging to the second grid point group are the same, the second component values are the same, and the third The second grid point group having component values different from each other and the first component value of each grid point being a second value different from the first value;
Including
The color conversion profile is data in which a plurality of sets of values corresponding to the first grid point group and a plurality of sets of values corresponding to the second grid point group are successively arranged in this order,
The image processing apparatus, wherein the first grid point is included in the first grid point group, and the second grid point is included in the second grid point group. The image processing apparatus according to any one of claims 1 to 3,
The plurality of grid points in the first color space are N × N × N grid points,
The plurality of grid points in the first color space are M × M × M specific grid points, and the M is (N−1) / (M−1) = k (N> M ≧ 2, k ≧ 2 (M, N, k are integers)) including the specific lattice point,
In the color conversion profile, each set of values in the second color space corresponding to the specific grid point represents each other regardless of whether or not it represents a color within a range that cannot be expressed by the image data generation unit. An image processing apparatus having different values. The image processing apparatus according to claim 4,
The first set of values corresponding to the first grid point and the second set of values corresponding to the second grid point are one of the M × M × M specific grid points. An image processing apparatus having the same value as the set in the second color space corresponding to a grid point. A method for creating a color conversion profile associated with image data generated by an image data generation device,
(A) A reference color conversion profile having a plurality of sets of values in a second color space corresponding to a plurality of grid points in the first color space depending on the image data generation device, wherein the plurality of sets of values Preparing the reference color conversion profile arranged according to a predetermined order of the plurality of grid points;
(B) a step of identifying two or more target grid points representing colors that cannot be expressed by the image data generation device among the plurality of grid points, wherein the two or more target grid points are Including one grid point and a second grid point, and no other grid point representing a color that can be expressed by the image data generation device exists between the first grid point and the second grid point, Process,
(C) creating a correction color conversion profile by changing two or more sets of values in the second color space corresponding to the two or more target grid points in the reference color conversion profile, The first set of values corresponding to the first grid points and the second set of values corresponding to the second grid points are changed to the same value; and
(D) compressing the corrected color conversion profile by a specific method to create a compressed corrected color conversion profile, the first set of values and the second set changed to the same value The data size of the compressed corrected color conversion profile is smaller than the data size of the compressed reference color conversion profile generated when the reference color conversion profile is compressed by the specific method. And said process,
A creation method comprising: The creation method according to claim 6,
The step (b)
(B1) preparing the test image data obtained by reading the test image by the image data generation device;
(B2) using the pixel values in the test image data to identify the two or more target grid points representing colors that cannot be expressed by the image data generation device among the plurality of grid points;
Including creation method.

Images