JP2003116012A - Conversion process part forming method, conversion process part forming equipment, storage medium and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the smoothing control to a lookup table is insufficient. SOLUTION: A lookup table is formed by using a lookup table and a lookup table after smoothing wherein smoothing is performed to the lookup table.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conversion processing section creating method, a conversion processing section creating method, a storage medium and a program in a device that prints on a plurality of different output media such as a printing machine and a printer.

[0002]

2. Description of the Related Art In an image device such as an inkjet printer, when RGB color signals input from an image input unit are converted into device colors (for example, CMYK) of the image device and a color image is output from an image output unit. , The color reproducibility should be kept good. As a technique for this, there is known a method of performing color conversion by using a three-dimensional look-up table (LUT) for pre-stage color conversion (color correction) and post-stage color conversion (color separation).

In the former-stage color conversion, so-called color reproduction space mapping is performed, in which a range in which color cannot be reproduced by the image output unit is compressed and mapped in a range in which color can be reproduced.

As this color reproduction space mapping technique, conventionally, when color conversion is performed using a three-dimensional look-up table (LUT) and color reproduction space mapping (color gamut conversion) is performed, the output color space (color The space formed by the color signal between the reproduction conversion system and the output system is divided into an area where color reproduction space mapping processing is performed and an area where that processing is not performed, and the input color space (input system and color reproduction conversion) There is known a configuration in which a color reproduction space mapping is performed by performing mapping on a space formed by a color signal with a system to determine a clipping region.

In the latter-stage color conversion, RGB from the image input unit is used.
A so-called color separation process is performed to convert the signal into the device color of the printer.

By the way, in the color conversion method using the LUT as described above, the values at the grid points on the LUT are often calculated independently, and there is no continuity with the values at the adjacent grid points. However, discontinuity may occur in the LUT on the basis of the signal value. For example, in Japanese Patent Laid-Open No. 2001-016476, in order to eliminate this discontinuity, smoothing is performed by a three-dimensional filter independently for R, G, and B channels. It is carried out. Further, in order to prevent gray from becoming a chromatic color by the smoothing processing, the processing target area is divided into a gray area and a chromatic color area, and the gray area is kept in the relationship of R = G = B. I try to do smoothing.

[0007]

However, when the above-mentioned conventional technique is applied to the pre-stage color conversion, smoothing is performed uniformly for the entire color space except gray and gray, so that, for example, in the vicinity of skin color, It is not possible to locally smooth (or smooth) only specific chromatic colors, such as preserving the tint before and after smoothing, and adjustments that take into account color fluctuations due to smoothing must be performed in advance during color adjustment. However, there was a problem that adjustment was difficult.

Further, when the prior art is applied to the preceding color conversion, since the gray area and the chromatic color area are processed completely separately, the gray area and the chromatic color around the gray area are processed. There was a case where the color change of was discontinuous.

Further, by applying the above-mentioned conventional technique to at least one of the front stage and the rear stage,
In the latter part, for example, near solid areas (maximum saturation of each color,
There is a problem in that a desired value cannot be held before and after smoothing in a portion different from the noise to be smoothed such as (the point at which the maximum density is obtained), for example, in the peak of the color signal change on the right side of FIG.

The present invention has been made in view of the above problems, and an object of the present invention is to locally (without smoothing) only a specific color of a chromatic color.

Another object of the present invention is to prevent discontinuity in tint change between chromatic colors on the gray line and around the gray.

It is still another object of the present invention to maintain a peak of a color signal change before and after smoothing and to selectively perform smoothing only on noise to be smoothed.

[0013]

In order to achieve the above object, the present invention uses a first look-up table and a look-up table after smoothing in which the first look-up table is smoothed. It is characterized in that a lookup table 2 is created. Further, the smoothing is performed according to a parameter for controlling the smoothing. Also,
The smoothing is performed according to the smoothing strength for each hue. The second lookup table is created from a weighted average of the smoothed lookup table and the first lookup table.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] [Structure] FIG. 1 is a block diagram showing a schematic structure of an image processing apparatus according to an embodiment.

In FIG. 1, the host computer 100
Is a word processor, spreadsheet, application software 101 such as an internet browser, an operating system (OS) 102, and various drawing command groups (image drawing command, text drawing command, graphics drawing command, etc.) issued from the application software 101 to the OS 102. ) To create print data representing an output image, a printer driver 103,
It also has software such as a monitor driver 104 that creates image data to be displayed on the monitor 106.

The host computer 100, as various hardware for operating these software,
CPU 108, hard disk drive (HDD) 10
7, RAM 109, ROM 110 and the like.

The configuration shown in FIG.
A personal computer 100 in which ws (registered trademark of Microsoft Corporation) is installed as the OS 102 and arbitrary application software 101 having a printing function is conceivable. Further, for example, an inkjet printer can be used as the printer 106, and a CRT or LCD can be used as the monitor 106.

The application software 101 of the host computer 100 is classified into text data classified into text such as characters, graphics data classified into graphics such as graphics, and photographic images based on the image displayed on the monitor 105. The output image data to be printed is created using the image data to be printed. When printing the output image, a print request is issued from the application software 101 to the OS 102, the text data portion is a text drawing instruction, the graphics data portion is a graphics drawing instruction, and
In the image data portion, a drawing command group configured as an image drawing command is sent to the OS 102.

When the OS 102 receives the print request,
A drawing command group is passed to the printer driver 103 corresponding to the printer to execute printing. Printer driver 103
Processes a print request and a drawing command group input from the OS 102, creates print data printable by the printer 105, and transfers the print data to the printer 105.

When the printer 105 is a raster printer, the printer driver 103 responds to the drawing command group by
Image correction processing is sequentially performed, and images are sequentially rasterized in an RGB 24-bit page memory. After all drawing commands have been rasterized, the printer driver 103
Converts the RGB data stored in the page memory into a data format printable by the printer 106, for example, CMYK data, and transfers the CMYK data to the printer 105.

FIG. 2 is a diagram for explaining the processing performed by the printer driver 103.

In FIG. 2, the image correction processing unit 120
Image correction processing is performed on the color information included in the drawing command group input from the OS 102. Specifically, the RGB color information is converted into a luminance / color difference signal, an exposure correction process is performed on the luminance signal, and then the corrected luminance / color difference signal is inversely converted into RGB color information.

The printer correction processing unit 121 refers to the image-corrected RGB color information and rasterizes the image based on a drawing command to generate a raster image on the page memory. Then, the raster image is subjected to color reproduction space mapping (gamut mapping), color separation into CMYK, gradation correction, and the like to generate CMYK data that determines the color reproducibility of the printer 105 for each pixel.

FIG. 3 is a diagram for explaining the processing of the printer correction processing section 121 in detail.

In FIG. 3, the input image data B1 is processed by the front color signal conversion unit B1 for color matching processing, the rear color signal conversion unit B3 for color separation processing in consideration of the characteristics of the ink jet printer, and the gradation correction unit B4. Gradation correction and halftone processing are performed, and the dot information of CMYKcm corresponding to each ink is transferred to the printer B5 to form an image.

[Deriving the pre-stage color processing table] Next, referring to FIG.
A method of deriving the pre-stage color processing table 212 used in the pre-stage color signal conversion unit B2 will be described in detail with reference to. still,
In the present embodiment, a table is used for description, but it goes without saying that a color conversion function equivalent to the following table may be used.

The pre-stage color processing table 212 is a three-dimensional LUT for performing color matching between RGB monitor and RGB printer output devices having different color reproducibility. The derivation of the pre-stage color processing table 212 is roughly based on a device-independent color space (Device I) of the monitor RGB data 205 and the printer RGB data 231.
(Nendent Space: DIS) data, and monitor RGB data 205 and printer RGB data 231 are associated with each other.

Conversion from monitor RGB to DIS Monitor RGB data 205 is XY which is DIS, by calculation using a conversion formula according to a standard such as sRGB.
Convert to Z color space data. Here, the chromaticity in the CIE L * a * b * color space is calculated in consideration of human color vision.

Printer RGB to DIS Conversion As the printer 105, dark ink CM is used in the embodiment.
Assume an inkjet printer that uses a total of six colors of ink, YK and cm of light ink. In an inkjet printer, it is necessary to perform color separation in consideration of the granularity of printed dots and the total amount of ink droplets that a recording medium can accept per unit time and unit area. After taking these conditions into consideration, the input RGB data is color-separated and an appropriate C
The post-stage color processing table 203 used in the post-stage color signal conversion unit B3 that outputs the combination of MYKcm inks is preset.

If the color processing of the printer is operated via the post-stage color processing table 203, the printer configuration, for example CM
The printer can be handled as an RGB device that simply processes RGB data, without being affected by the configuration such as four colors of YK or six colors of CMYKcm.

In an ink jet printer, since a variety of complicated factors such as a change in color due to color mixture of ink and a change in color due to ink permeation into a recording medium are related to color development, its color development characteristic is predicted. Is difficult to do. Therefore, in order to express the color reproducibility of the inkjet printer while avoiding the difficulty of predicting the color development, L * a corresponding to a specific printer RGB is obtained by the following method.
* B * data is required. That is, possible printer RGB
A color patch is printed at a combination of data and at an appropriate sampling interval, and the color patch is measured by a colorimeter such as Spectrolino manufactured by Gretag Co. to obtain grid point data in the printer color reproduction space. If the L * a * b * value of the grid point is obtained, a known interpolation calculation such as tetrahedral interpolation is used for the L * a * b * value (DIS coordinate value) corresponding to an arbitrary printer RGB value. Then, it can be obtained from the lattice point L * a * b * value.

In the embodiment, the sampling interval of the post-stage RGB signal values is "16", and the post-stage RGB signal values 0, 1
6, 32, 48, 64, 80, 96, 112, 128,
144, 160, 176, 192, 208, 224, 2
17 × 17 × 17 with 40 and 255 grid points
The post-stage color processing table 203 of the lattice (4913 points) is used.

L * of grid points in the post-stage color processing table 203
For the a * b * data, the grid points are thinned out (corresponding to the sampling interval “32”), and the subsequent RGB signal values 0, 32, 64, 9
6, 128, 160, 192, 224, and 255 (9 × 9 × 9) grids (729 points) corresponding to grid points, that is, a subset of the post-stage color processing table 203 that is actually used is color-measured, and 729 L * a * b * data 20
Ask for 4.

Gamut Mapping Next, gamut mapping for converting the monitor L * a * b * data 206 into the printer target L * a * b * data 207 will be described with reference to FIG.

In the L * a * b * color space shown in FIG. 5,
The monitor RGB gamut (color reproduction range) is the printer RG.
The lightness L * and the saturation S are wider than those of the B gamut.
Therefore, by simply associating the monitor RGB and the printer RGB in the L * a * b * color space, all the RGB combinations displayed on the monitor cannot be output as appropriate chromaticity by the printer. Therefore, L * a *
Although the b * values cannot be matched, gamut mapping is performed so that the printer can output a color tone similar to the monitor display.

As a gamut mapping method, in the embodiment, the gamut of the monitor RGB data 205 is changed on the L * a * b * color space to change the L of the printer target.
* A * b * data 207 is generated so that the L * a * b * data 207 of the printer target is inside the gamut of the printer RBG, for example, while maintaining the lightness L * as shown in FIG. , Saturation S = √ (a * ² + b * ² )
Perform processing such as lowering.

Generation of pre-stage color processing table By the above gamut mapping, the L * a * b * data 207 of the printer target is adjusted so as to be in the RGB gamut of the printer. That is, the L * a * b * data 207 of the printer target can be associated with the printer RGB data 231 by following the processes of P1 → P2 → P3 shown in FIG.

Here, the L * a * of the printer target converted to fit in the RGB gamut of the printer.
For each point (L * a * b * value) of b * data 207,
L * a * b * → RGB conversion must be performed. Here, RGB is obtained by tetrahedral interpolation using L * a * b * data 207 of the printer target of L * a * b * → RGB conversion and the points forming the RGB gamut of the printers around it. Extrapolate the points that do not fit in the RGB gamut of the printer. In addition, L * a * b
As the * → RGB conversion method, it is also possible to use an inverse tetrahedral interpolation, a conversion method that forms a printer model using a neural network or multiple regression equation.

On the other hand, the RGB data 205 of the monitor is associated with the L * a * b * data 207 of the printer target by following the processing of 205 → 206 → 207. Therefore, the above two processes are sequentially followed, 205 → 2
06 → 207 → P1 → 204 → P2 → 203 → P3 → 2
It is possible to finally obtain the pre-stage color processing table 212 by sequentially converting into 31.

In the following, with further reference to FIG.
The correspondence between the B, CMYK signal values and the L * a * b * values will be described in detail.

FIG. 6 shows White → Red in the color solid of FIG. 7 corresponding to the color gamut of the printer and the monitor.
9 is a graph schematically showing a change in chromaticity of an axis traced in the order of → Black. In addition, from the left, the CM on the RGB printer
It shows changes in YKcm signal switching, printer gamut, and monitor RGB signal values.

For example, the printer CMY shown on the left side of FIG.
How to switch the Kcm signal is R in the bright area of m and Y.
ed is expressed, and M and Y have the maximum saturation (the center part of the figure), and the complementary color C is added to M and Y, so that the colors become darker,
Eventually, K enters and the color components of M and Y are reduced to reach an achromatic Bk (the central part of the figure).

Similarly, the way of switching the monitor RGB signals on the right side of FIG. 6 is such that the maximum brightness of any of the RGB signals is the maximum (White), the G and B signals are gradually reduced, and the brightness is lowered, and the relative brightness is reduced. The saturation due to the R signal increases.
Further, the saturation is maximized at the point where the G and B signals are zero and the R signal is 255, and thereafter, the brightness and the saturation are both lowered by weakening the R signal itself.

By the way, in the above-mentioned "conversion from printer RGB to DIS", when the printer gamut is constructed, the combination of RGB sampled with the step width 32 is printed by the printer and the L * a * b * data is obtained. Obtained. The sampling points of the printer L * a * b * data 202 shown in FIG. 5 to be subjected to color measurement are indicated by horizontal broken lines in FIG.

[Smoothing] The pre-stage color processing table obtained by the above processing is affected by the error in the L * a * b * value of the color prediction model of the printer, the difference in the processing method at the printer gamut boundary, and the like. , Is discontinuous.

Therefore, in the present embodiment, the generated pre-stage color processing table is smoothed.

Hereinafter, the smoothing method of this embodiment will be described in detail with reference to the drawings.

Smoothing processing section The smoothing processing section has a pre-stage color processing table 212 (17) created in the above-mentioned "creation of pre-stage color processing table".
X17x17 RGB-R'G'B 'correspondence table),
It is assumed that the data is stored in the memory as an array of LUT_SRC []. Also, LUT_SMOO
TH [] and LUT_DEST [] have the same form,
LUT_SRC [] is respectively the pre-stage color processing table after smoothing and the pre-stage color processing table that is the output of the smoothing processing unit in FIG. 9.

The data input to the smoothing processing section in FIG. 9 is the parameter P indicating the smoothing intensity for each color.
(Here 0 <= p <= 1. P is p_R, p_Y, p_
G, p_C, p_B, and p_M, and vectors having parameters corresponding to the six hues) are input to the color smoothing processing unit 901. Then, the pre-stage color processing table LUT_SMOOTH [] subjected to the smoothing process for each color in the color-specific smoothing processing unit 901 and the pre-stage color processing table LUT_SRC [] (21 before the smoothing process)
2), L * a * b * data LAB [] (204) at the subsequent R'G'B 'lattice points, and a threshold value th_smooth indicating the amount of change in the L * a * b * value allowed before and after smoothing.
Is input to the selector control signal processing unit 902. From the selector control signal processing unit 902, if the amount of change in the L * a * b * value before and after smoothing is within the allowable range, smoothing processing is performed for each color. Pre-stage color processing table LUT
If _SMOOTH [] is outside the allowable range, the pre-stage color processing table LUT_SRC [] before smoothing processing
A selector control signal for selecting (212) is output. In the selector 903, the pre-stage color processing table LUT_SRC [] (212), LUT_S before smoothing processing is performed for each grid point by the selector control signal.
Either MOOTH [] is selected and output as the output table LUT_DEST [] of the smoothing processing for each color.

Hereinafter, the smoothing processing unit for each color of FIG. 9 which constitutes a part of the above-mentioned smoothing processing unit will be described with reference to FIG.
Details will be described with reference to 0.

Color-based smoothing processing section In the color-based smoothing processing section 901, R, Y, G, C,
Smoothing with different intensities is performed for each of the six hues B and M.

The color-based smoothing processing unit 901 includes a pre-stage color processing table LUT_SR before smoothing processing.
C [] (212) and a parameter P representing the smoothing intensity for each of the six hues of R, Y, G, C, B and M (where P is P = [p_R, p_Y, p_G, p_C, p_
B, p_M] vector. ) Is input, and LUT_DEST [] is output as a smoothing result for each color.

The input pre-stage color processing table LUT_SRC [] (212) before the smoothing processing is smoothed by the simple smoothing processing unit 1001 using the functional expression of Formula 1 and output as LUT_SMOOTH [].

[0054]

[Equation 1]

Here, k, j, i are 1 or more, (17
-1) It shall take a value between the following.

Smoothed pre-stage color processing table LUT_S output from the simple smoothing processing unit 1001.
Using MOOTH [], the Δ described in FIG.
R, ΔY, ΔG, ΔC, ΔB and ΔM are obtained. Using this and the input smoothing intensity P for each color, the color-based operation unit 1002 obtains a smoothing result for each color by the operation represented by the operation expression of Equation 2.

[0057]

[Equation 2]

Here, R ', G', and B'are R, G, and B elements at certain lattice points in the array LUT_DEST [] having vectors as elements, and R, G, and B are arrays having vectors as elements. R, G, and B elements at each lattice point of LUT_SRC [] and Rsm, Gsm, and Bsm are R, G, and B elements at a lattice point of an array LUT_SMOOTH [] having vector elements.

Further, ΔR, ΔY, ΔG, ΔC, ΔB, Δ
M is determined by the magnitude relationship of each RGB in FIG.
In the six areas shown in Fig. 12, the values are respectively obtained as shown in Fig. 12. For example, as for the RED system color, as the distance from the RED axis becomes smaller as shown in Fig. 13, the value becomes continuously smaller. And YEL on both sides of the RED axis
It is set to be 0 on the LOW axis and the MAGENTA axis. As a result, it is possible to control smoothing such that local smoothing is performed or not performed, and in addition, discontinuous occurrence of color change can be prevented. In addition, it becomes possible to improve the reproducibility near the solid portion.

The obtained smoothing result is the LUT
_DEST [] is output from the color smoothing processing unit.

Here, as the smoothing method, an example of a simple average of the values of the surrounding grid points and the grid point of interest in three dimensions has been described, but of course the same effect can be obtained by using other smoothing methods.

The selector control signal processing section 902 which constitutes a part of the smoothing processing section will be described below with reference to FIG.
1 will be described in detail.

Selector control signal processing unit The selector control signal processing unit 902 has a pre-stage color processing table LUT_SRC [] (21) before smoothing processing.
2), pre-color processing table L after smoothing processing for each color
UT_SMOOTH [] and the colorimetric data table LAB [] (204) in the subsequent stage are input, and a selector control signal that allows smoothing when the change in tint (color difference = ΔE) is within the reference value before and after smoothing is input. Output.

LUT_SRC [] (212) and LUT
_SMOOTH [] together with the colorimetric data table LAB [] (204) in the subsequent stage respectively, the color prediction unit (1101,
1102), and the colorimetric data table LA at the subsequent stage is input.
By performing tetrahedral interpolation using B [] (204), L *
converted to a * b * value, respectively SRC_LA
B [] and SMOOTH_LAB [] are stored.

L * a * corresponding to each table obtained above
b * value SRC_LAB [], SMOOTH_LA
B [] is input to the ΔE calculation unit 1103, ΔE (color difference) before and after smoothing of the corresponding grid point is calculated, and stored in the color difference table delta_e [].

The comparing unit 1104 compares the input maximum allowable value th_smooth of ΔE with delta_e [] at each grid point, and if the change in ΔE before and after smoothing is within the allowable range. , Selector 9
03 outputs a selector control signal for selecting LUT_SMOOTH [], and a selector control signal for selecting LUT_SRC [] when the change in ΔE is outside the allowable range. With this configuration, it is possible to smooth noise while suppressing a change in color tone.

Next, the post-stage color signal conversion unit of FIG. 6-B3 will be described. For the sake of simplicity, the following description will be on the post-stage color conversion of the 3 or 4 color system.

[0068]

[Equation 3]

[0069]

[Equation 4]

In the latter-stage color conversion unit of FIG. 6-B3, the printer R'G'B 'signal obtained through the former-stage color signal conversion unit is converted into the CMYK8 [bit] color signal value corresponding to the ink of the printer. . The conversion of the color signal from R'G'B 'to CMYK can be performed as shown in Formula 3 and Formula 4 by using the color masking method which is a conventionally known technique. There are various methods for selecting the signal value of K. For example, a vector [D_r−KD] obtained by subtracting the K value from each of the vector elements on the rightmost side of Expression 3 is used.
_G−K D_b−K] ^ t is replaced with the vector on the rightmost side, and a trial is performed while restricting the K value by using the condition that the color signal value CMY corresponding to the ink amount is always positive or zero. Misleadingly looking for the masking matrix, K
Any method of determining the value can be used.

In the present embodiment, the latter-stage color signal conversion table is generated by using the above method, and the final latter-stage color signal conversion table is determined by manually performing fine adjustment if necessary.

Next, the gradation correction section of FIG. 6-B4 will be described.

In the gradation correction unit of FIG. 6-B4, the CMYK8 in which the color signals of the input image are sequentially converted by the front and rear conversion units.
[Bit] CMYK2 that can print data with a printer
[Bit] Convert to data. For this gradation correction, for example, a Bayer type 16 × 16 matrix is applied to each of the C, M, Y, and K images, and 1 when the pixel value on the corresponding image is larger than the matrix element, If the pixel value is less than or equal to the element of the matrix, it can be obtained by setting it to 0. Also, an error diffusion method or the like may be used as the halftoning method.

For example, Japanese Patent Laid-Open No. 3-1 used in this embodiment.
Instead of the interpolation described in Japanese Patent No. 3066, other interpolation methods such as cubic interpolation may be used.

As the color reproduction space mapping technique, there are several conventionally known methods, but they are not particularly specified in this embodiment.

[Modification of Embodiment] Change of Control Signal Calculation Method of Selector Control Signal Processing Unit In the first embodiment, when the selector control signal is set, the color prediction value before and after smoothing (L * a *) is set. The amount of change before and after smoothing is specified based on b *).

However, the amount of change before and after smoothing is RG
Using the signal value of B, for example, ΔE = sqrt ((Rsr
c-Rsm) ^ 2 + (Gsrc-Gsm) ^ 2 + (Bs
rc-Bsm) ^ 2) or the like. In this case, the color prediction units 1101, 1102 and L of FIG.
AB [] becomes unnecessary, LUT_SRC [] is used instead of SRC_LAB [], and LUT_SMOOTH [] is used instead of SMOOTH_LAB [].
The system configuration can be simplified and the amount of memory used can be reduced.

Further, instead of ΔE, the hue difference ΔHU
It is also within the scope of the present invention to use E, the difference ΔC in saturation, the difference ΔL in lightness, and the like.

Modification of Simple Smoothing Processing 1001 In the first embodiment, the simple smoothing processing unit 1001 is used.
Although the number of times of smoothing is 1 in the above description, a fixed or variable parameter n may be given to the number of times of smoothing to perform smoothing n times. In this case, smoothing can be written more effectively. In this case, the simple smoothing processing unit 1 of FIG.
As an input to 001, the (n-1) th smoothing result may be recursively input and smoothed.

Change of the color-specific arithmetic processing unit 1002 In the first embodiment, the color-specific processing in the color-specific arithmetic processing unit 1002 is classified into 6 hues of RYGCBM, but L = (max
(R_, max (g_, b _)) + min (r_, mi
n (g_, b _))) / 2 or the like may be used for each brightness direction.

Similarly, the color-based processing in the color-based arithmetic processing unit 1002 is V (rr-r ') = exp (-α. (Rr-')).
It is possible to perform smoothing around a specific color by setting the smoothing strength in each lattice using a spherical potential such as / (rr ′).

Further, in order to set the smoothing strength of each grid, the smoothing strength of each grid is stored 3
It is also conceivable to use a dimensional look-up table.

Parameter setting method Even if the parameters such as the smoothing strength, the allowable value of mutation before and after smoothing, and the number of smoothing are fixed, G
A UI may be provided to allow the user to input data.

In such a case, in order to allow the user to confirm and set the smoothing effect, RG
It is also effective to provide a graph of signal values such as B and L * a * b * values, and a preview screen that displays both images processed by the lookup table before smoothing and the lookup table after smoothing. is there. Of course, it is easier to confirm if both images processed by the look-up table before smoothing and the look-up table after smoothing the sample image are displayed at the same time.

[Other Embodiments] The present invention realizes the functions of the embodiments in an apparatus or system connected to the various devices so as to operate the various devices so as to realize the functions of the above-described embodiments. The program code itself and a means for supplying the program code to a computer, for example, a storage medium storing the program code constitutes the present invention.

A storage medium for storing the program code is, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-R.
An OM, a magnetic tape, a non-volatile memory card, a ROM, or the like can be used.

Further, not only the functions of the above-described embodiments are realized by executing the supplied program code by the computer, but also the OS (operating system) in which the program code is operating in the computer, or another Needless to say, the program code is also included in the embodiments of the present invention when the functions of the above-described embodiments are realized in cooperation with application software or the like.

Further, the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, and then stored in the function expansion board or the function storage unit based on the instruction of the program code. Needless to say, the present invention also includes a case where a CPU provided therein performs a part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

Further, the above-mentioned plurality of embodiments may be combined.

As described above, the peaks of the color signal change can be maintained before and after smoothing, and only the noise of the specific color of the chromatic color to be smoothed can be selectively smoothed.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration.

FIG. 2 is a diagram illustrating a process performed by a printer driver.

FIG. 3 is a diagram illustrating color processing performed by a printer driver.

FIG. 4 is a diagram conceptually illustrating gamut compression in a saturation direction on a (brightness-saturation) plane.

FIG. 5 is a diagram showing a data flow of a pre-stage LUT derivation process for performing color matching.

FIG. 6 is a diagram schematically showing grid points for color measurement on a two-dimensional plane.

FIG. 7 is a diagram showing a relationship between a colorimetric point added by the method of the first embodiment of the present application, a post-stage LUT (left diagram), a printer Gamut (middle diagram), and a pre-stage LUT (right diagram).

FIG. 8 is an enlarged view of a side having lower lightness than the maximum saturation point in FIG.

FIG. 9 is a diagram showing a relationship between a colorimetric point added by the method of the second embodiment of the present application, a post-stage LUT (left figure), a printer Gamut (middle figure), and a pre-stage LUT (right figure).

FIG. 10 is a diagram schematically showing two-dimensionally the colorimetric points added to the conventional equidistant colorimetric points by the method of the first embodiment of the present application.

FIG. 11 is a diagram schematically showing two-dimensionally the colorimetric points added to the conventional equidistant colorimetric points by the method of the second embodiment of the present application.

FIG. 12 is a diagram schematically showing two-dimensionally the colorimetric points added to the conventional equidistant colorimetric points by the method of the second embodiment of the present application.

FIG. 13 is a diagram showing an example of ΔR.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/60 B41J 3/00 B (72) Inventor Jushu Fukao 3-30 Shimomaruko, Ota-ku, Tokyo No. 2 F-term in Canon Co., Ltd. (reference) 2C262 AA02 AA24 AB11 BA02 BA09 BA18 BC01 BC19 5B057 CE05 CE18 CH01 CH07 CH11 DA16 DB06 DB09 5C077 MP08 PP02 PP32 PP33 PP35 PP36 PQ08 PQ12 PQ22 PQ23 SS06 TT02 5C079B11 HB01 HB03 HB01 HB03 HB01 HB03 H12 LB02 MA01 MA04 MA11 MA17 PA03

Claims (18)

[Claims] 1. A first look-up table and the first look-up table.
The conversion processing unit creating method, wherein the second lookup table is created using the smoothed lookup table obtained by performing smoothing on the lookup table of FIG. 2. The conversion processing unit creating method according to claim 1, wherein the smoothing is performed according to a parameter for controlling the smoothing. 3. The smoothing is performed according to a smoothing intensity for each hue.
The conversion processing part creation method described in the item. 4. The conversion unit creating method according to claim 1, wherein the second look-up table is created from a weighted average of the smoothed look-up table and the first look-up table. 5. The conversion unit creating method according to claim 2, wherein the parameter defines a change amount of the lookup table before and after the smoothing. 6. The conversion unit creating method according to claim 5, wherein the defined parameter relates to chromaticity. 7. The conversion unit creating method according to claim 2, wherein the parameter is a smoothing intensity corresponding to at least one specific color. 8. The conversion unit creating method according to claim 2, wherein the parameter is automatically set. 9. The conversion unit creating method according to claim 2, wherein the parameter is manually set. 10. A result of smoothing the lookup table after the smoothing and the lookup table before smoothing for each color is obtained, and the obtained smoothing result and the first lookup table are used to perform the smoothing. 2. The conversion unit creation method according to claim 1, wherein the lookup table No. 2 is created. 11. The second lookup table,
According to the color difference, the hue difference, the saturation difference, or the brightness difference of the first lookup table, the second
12. The conversion unit creating method according to claim 11, further comprising selectively using the look-up table of 1. and the first look-up table. 12. The conversion unit creating method according to claim 1, wherein performing the smoothing means performing the smoothing a plurality of times. 13. The method according to claim 1, wherein the smoothing is performed according to a smoothing intensity for each lightness. 14. The method according to claim 1, wherein a preview image processed using the look-up table before and after smoothing is displayed. 15. The conversion unit creating method according to claim 1, wherein the lookup table to be smoothed relates to RGB. 16. A conversion processing unit that creates a second lookup table using the first lookup table and the smoothed lookup table obtained by smoothing the first lookup table. Creation device. 17. A recording medium storing a computer-readable program, a procedure for obtaining a first look-up table, a procedure for obtaining a smoothed look-up table by smoothing the first look-up table, A storage medium storing a program, comprising: the lookup table; and a procedure of creating a second lookup table using the smoothed lookup table obtained by smoothing the lookup table. 18. A procedure for obtaining a first look-up table, a procedure for obtaining a smoothed look-up table obtained by smoothing the look-up table, and smoothing for the first look-up table and the look-up table. And a procedure for creating a second lookup table using the lookup table after smoothing.