JP2003324620A - Image processing equipment and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image simply which corresponds to the desired color reproduction of a user. <P>SOLUTION: The user selects arbitrary color reproduction between first color reproduction, which reproduces an image displayed in a display device visually and faithfully and second color reproduction which reproduces memory colors such as skin color and green of plants more preferably. A color mapping part 22 sets a mapping LUT, corresponding to the purpose of color reproduction. An input device model, converting part 21, receives RGB data and converts the data to Lab data. On the basis of the Lab data, the color mapping part 22 performs color conversion process to the respective color of skin color, blue, green and gray of intermediate lightness and forms and outputs L' a' b' data. By using the L' a' b' data, an image-forming device model converting part 23 forms CMYK data which correspond to an image-forming device, and outputs the data to an image output part 130. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing device and an image processing method.

[0002]

2. Description of the Related Art Recent color printers are provided with various color conversion / processing functions in order to obtain desired color reproduction by a user.

[0003]

However, the detailed color conversion / processing function has a high degree of freedom, and if it is used incorrectly, not only the desired image is obtained, but also unacceptable results are often generated. Obtaining a desired image requires a lot of knowledge and experience.

The present invention has been made in view of the above problems, and an object thereof is to easily obtain an image according to a color reproduction desired by a user.

[0005]

In order to achieve the object of the present invention, for example, an image processing apparatus of the present invention has the following configuration.

That is, the input RGB data is converted into the first RGB data.
Intermediate data conversion means for converting to intermediate data, holding means for holding a color conversion table corresponding to a plurality of types of color reproduction, selection means for selecting a desired color reproduction, and a plurality of types of holding means for holding the color conversion table. A color conversion table that performs a color conversion process on the first intermediate data by using a color conversion table that corresponds to a desired color reproduction among the color conversion tables that corresponds to the color reproduction to generate second intermediate data. Means and an output means for generating and outputting output data based on the second intermediate data.

In order to achieve the object of the present invention, for example, the image processing method of the present invention has the following configuration.

That is, a color conversion table corresponding to a plurality of types of color reproduction is held in a memory, and an intermediate data conversion step of converting the input RGB data into first intermediate data and a desired color reproduction are selected. And a color conversion table corresponding to a desired color reproduction among color conversion tables corresponding to a plurality of types of color reproduction stored in the memory, and the color conversion processing is performed on the first intermediate data. And a color conversion step of generating second intermediate data, and an output step of generating and outputting output data based on the second intermediate data.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail according to preferred embodiments with reference to the accompanying drawings.

FIG. 1 shows the basic configuration of the image processing apparatus according to this embodiment and shows the relationship with the peripheral equipment of the image processing apparatus. An image processing apparatus 100 according to the present exemplary embodiment includes a PC (personal computer), a workstation, and the like, and includes each unit described below. 11
An image input unit 0 inputs image data from the image input device 101 and the image recording medium 102, which will be described later, to the image processing unit 120. An image processing unit 120 performs each image processing described below,
An image output unit 130 outputs the image data that has undergone image processing by the image processing unit 120 to the image forming apparatus 103 described below.

An image input device 101 is composed of a digital camera, a scanner or the like, and supplies an image to the image processing device 100 as electronic data. An image recording medium 102 is composed of a CD-ROM, a DVD-ROM, or the like, and an image is recorded as electronic data. Like the image input apparatus 101, the image is supplied to the image processing apparatus 100 as electronic data. To do. An image forming apparatus 103 functions as a printer and prints an image based on the image data output from the image output unit 130 on a storage medium such as paper. More specifically, the image forming apparatus 1
03 is a color that forms an image on a paper surface with cyan (hereinafter C), magenta (hereinafter M), yellow (hereinafter Y), and black (hereinafter K) ink or toner. It is a printer.

FIG. 10 shows the basic configuration of the image processing apparatus 100. 1001 is a CPU, RAM 1002 and RO
The program and data stored and stored in M1003 are used to control the entire apparatus and perform data communication with the image forming apparatus 103, and also perform image processing including color conversion processing, which will be described later. A RAM 1002 has an area for temporarily storing programs and data loaded from an external storage device 1006 and a recording medium drive, and a CPU 1
It also has a work area used when 001 performs various processes. A ROM 1003 stores programs and data for controlling the entire apparatus.

An operation unit 1004 is composed of a keyboard, a pointing device such as a mouse, or the like, and various instructions from a user can be input to the apparatus. A display unit 1005 includes a CRT, a liquid crystal screen, and the like, and can display images, character information, and the like. Reference numeral 1006 denotes an external storage device as an external device connected via a hard disk drive or a communication line, and an OS (not shown) for controlling the entire apparatus and the image processing program 1 functioning as the image processing unit 120.
Holds 007 as a file, and if necessary, R
It is read by the AM 1002 and is the execution target of the CPU 1001.

A recording medium drive 1008 functions as the image input unit 110, reads image data recorded in the image recording medium 102, and outputs the image data to the RAM 1002 or the external storage device 1006. An I / F (interface) unit 1009 functions as a higher-order image input unit 110 and stores image data from the image input device 101 in a RAM.
1002 and the external storage device 1006. 1010
Is an I / F (interface) unit, and the image output unit 1
It functions as 30, and outputs image data, which is a result of color conversion described later, to the image forming apparatus 103. Reference numeral 1011 is a bus connecting the above-mentioned units.

FIG. 2 shows a functional configuration of the image processing unit 120. The RGB color signals forming the image data are converted by the input device model conversion unit 21 into the color signals of the respective components L, a, and b, and the respective color signals are reproduced by the color mapping unit 22 in various color reproductions described later. L ', according to
The signals a ′ and b ′ are converted into color signals that can be reproduced by the image forming apparatus 103. Then, the respective signals of L ′, a ′, and b are converted by the image forming apparatus model conversion unit 23 into CMYK color signals depending on the image forming apparatus 103. The input device model conversion unit 21 is typically sRGB.
According to the conversion formula based on the standard (IEC61966), R
A uniform color space CIELAB corresponding to color perception of GB color signals
Convert to the upper color signal Lab. The image forming apparatus model conversion unit 23 typically uses a known color separation look-up table (hereinafter referred to as LUT) method to transfer the color signals L′ a′b ′ in the CIELAB color space to the image forming apparatus 103. It is converted into a dependent output color signal CMYK.

The color separation LUT is an appropriate discrete L'a'b 'based on the CMYK color signals and the colorimetric values (CIELAB values) of the print output from the image forming apparatus 103.
The CMYK color signal corresponding to the input color signal (CIELAB value) is obtained and created based on this relationship. The output color signal CMYK corresponding to the arbitrary color signal L'a'b 'is obtained by a known interpolation method using the color separation LUT.
The color mapping unit 22 converts the input color signal Lab into a color signal L′ a′b ′ that can be reproduced by the image forming apparatus 103. Generally, when the input color signal Lab is the image forming apparatus 10,
3 can be reproduced, the input color signal is used as it is as the output color signal L'a'b ', and if the input color signal cannot be reproduced by the image forming apparatus 103, it is converted by a known mapping method.

However, even if the input color signal Lab can be reproduced by the image forming apparatus 103, if the input color signal is used as it is as the output color signal, it is impossible to realize high-level color reproduction. Therefore, in the present embodiment, a target color, which will be described later, is set according to the purpose of color reproduction, and even when the input color signal can be reproduced by the image forming apparatus 103, the color signal is converted based on the target color to obtain the advanced color. Achieves excellent color reproduction. In the present embodiment, for the purpose of the color reproduction, there are two color reproductions generally required for a color printer, 1) a first color reproduction that faithfully reproduces an image displayed on a monitor, and 2) a skin color or a green of a plant. The second color reproduction that more preferably reproduces the memory color is taken up. Regarding 1), specifically, the display unit 100
The reproducibility in which the image displayed in No. 5 and the image when this image is formed on the paper are visually recognized as the same color. Regarding 2), specifically, each hue such as flesh color, blue, and green is rotated in a predetermined direction in the CIELAB color space by a predetermined amount in the a * and b * planes for the image with the first reproducibility, and It refers to reproducing an image brighter than the image according to the first reproducibility.

The color mapping unit 22 is typically a mapping LU integrated with the input device model conversion unit 21.
It is realized as T24. That is, mapping LUT2
4 (actually, the color mapping section 22) holds a plurality of types of RGB input color signals and the color-mapped output color signals L'a'b 'corresponding to the respective RGB input color signals in association with each other. ing. That is, this mapping LU
By referring to T24, L'a'b 'for an appropriate RGB input color signal can be uniquely obtained by a color reproduction instruction from the operation unit 1004 by the user. In addition,
The L'a'b 'color signal corresponding to an arbitrary RGB input color signal is obtained by a known interpolation method using the mapping LUT 24.

Next, the target colors for the first color reproduction and the second color reproduction will be described. The target color is an output color signal L'a'b 'that is converted by the color mapping unit 22 from a specific input color signal Lab according to the purpose of color reproduction. Typically, it is a colorimetric value of a color to be reproduced by a specific RGB input color signal.

A color conversion process for realizing the first color reproduction and the second color reproduction for each skin color, blue color, green color, and gray color of intermediate lightness by using the mapping LUT 24 will be described below.

<Skin color> When the purpose of color reproduction is the first color reproduction, the input color signal Lab corresponding to the skin color is converted into the output color signal Lm'am'bm 'from magenta. Specifically, the input color signal Lab is changed to CIELA as shown in FIG.
Input color signal Lab in a *, b * plane in B color space
Is converted into a color (Lm'am'bm ') indicated by the position rotated clockwise around the lower left corner.

When the purpose of color reproduction is the second color reproduction, the output color signal Lm 'for the purpose of the first color reproduction is obtained.
Output color signal L from magenta more than am'bm '
converted to p'ap'bp '. Specifically, when the first color reproduction is performed on the input color signal Lab with the position of the input color signal Lab within the a * and b * planes in the CIELAB color space as shown in FIG. The color (Lp'ap'b) indicated by the position rotated more clockwise than
p '). FIG. 3 is a schematic diagram showing conversion of the input color signal Lab corresponding to the skin color in the CIELAB color space.

<Green> When the purpose of color reproduction is the first color reproduction, the input color signal Lab corresponding to green is converted into the output color signal Lm'am'bm 'of cyan. Specifically, the input color signal Lab is changed to CIELA as shown in FIG.
Input color signal Lab in a *, b * plane in B color space
Is converted into a color (Lm'am'bm ') indicated by the position rotated counterclockwise around the lower right corner.

When the purpose of color reproduction is the second color reproduction, the output color signal Lm 'for the purpose of the first color reproduction is obtained.
It is converted into an output color signal Lp'ap'bp 'which is the same as am'bm' or more cyan. Specifically, the input color signal Lab is set to the CIEL as shown in FIG.
Input color signal La in the a * and b * planes in the AB color space
The color indicated by the position where the position of b is rotated counterclockwise more than when the first color reproduction is performed centering on the lower right corner (L
p'ap'bp '). FIG. 4 is a schematic diagram showing conversion in the CIELAB color space of the input color signal Lab corresponding to green.

<Blue> When the purpose of color reproduction is the first color reproduction, the input color signal Lab corresponding to blue is converted into the output color signal Lm'am'bm 'of cyan. Specifically, the input color signal Lab is changed to CIELA as shown in FIG.
Input color signal Lab in a *, b * plane in B color space
Is converted into a color (Lm'am'bm ') indicated by the position rotated clockwise around the upper left corner.

When the purpose of color reproduction is the second color reproduction, the output color signal Lm 'for the purpose of the first color reproduction is obtained.
Output color signal L from magenta more than am'bm '
converted to p'ap'bp '. Specifically, when the input color signal Lab is subjected to the first color reproduction with the position of the input color signal Lab within the a *, b * plane in the CIELAB color space as shown in FIG. It is converted to a color (Lp'ap'bp ') indicated by a position rotated clockwise by a larger amount. FIG. 5 is a schematic diagram showing conversion of the input color signal Lab corresponding to blue color in the CIELAB color space.

4) The input color signal Lab corresponding to gray of intermediate lightness, that is, an achromatic color, is an output color signal Lm ′ from blue when the purpose of color reproduction is the first color reproduction and the second color reproduction. It is converted into am'bm 'and Lp'ap'bp'.
Specifically, as shown in FIG. 7, on the a * and b * planes in the CIELAB color space, the color (Lm'am'bm) indicated by the position translated from the position of the input color signal Lab in the minus direction of the b * axis. ', Lp'ap'bp'). FIG. 7 is a schematic diagram showing conversion in the CIELAB color space of the input color signal Lab corresponding to gray of intermediate lightness, that is, achromatic color.

The skin color, the blue color, the green color, and the gray of the intermediate brightness may be determined by referring to the RGB data input by the input device model conversion section 21 or the color mapping section 22. Alternatively, the determination may be made by referring to the Lab data.

Further, the brightness of the entire image is changed by performing the conversion for each color. Mapping L in FIG.
The change in brightness component when color conversion is performed using the UT 24 is shown. In the figure, the horizontal axis represents the brightness component L before the color conversion, and the vertical axis represents the brightness component L ′ after the color conversion.
The curve shown by the solid line shows the brightness component Lm 'in the first color reproduction, and the curve shown by the dotted line shows the brightness component Lp' in the second color reproduction. Below is the equation for this curve,
That is, the relational expression between the brightness component L before the color conversion and the brightness component L ′ after the color conversion is shown below.

Lo = Li × (Low-Lobk) / (Liw-Libk) + Lobk where Li is the brightness component of the input color signal Lab, and Lo is the output color signal (the brightness component Lm in the case of the first color reproduction). ', The brightness component Lp in the case of the second color reproduction'), Liw and Low are the maximum values of the L components that can be input / output, and Libk and Lobk are the minimum values of the L components that can be input / output. . Further, when the purpose of color reproduction is the second color reproduction, it is converted into Lp 'which is brighter than the brightness component Lm' of the output color signal for the purpose of the first color reproduction. That is, the image in which the second color reproduction is realized becomes a brighter image than the image in which the first color reproduction is realized.

Next, FIG. 8 shows a flow chart of the color conversion processing performed by the image processing apparatus in this embodiment. First, the user uses the operation unit 1004 to reproduce the first color that faithfully reproduces the image displayed on the display unit 1005, and the second color that more preferably reproduces a memory color such as skin color or green of plants. An arbitrary color reproduction between the reproduction and the reproduction is selected (step S801).

Next, the color mapping section 22 sets a mapping LUT corresponding to the purpose of color reproduction (step S802). Next, when the input device model conversion unit 21 receives the RGB data from the image input device 101 or the image recording medium 102 via the image input unit 110 (step S803), it converts this into Lab data, and further the color mapping unit. 22 performs the above color conversion processing for each color on the Lab data to generate and output L'a'b 'data (step S804).

Then, using this L'a'b 'data,
The image forming apparatus model conversion unit 23 generates CMYK data according to the image forming apparatus 103 and outputs the CMYK data to the image output unit 130 (step S805). The image input unit 110
When it is determined that the data input to is the final data, the processing ends.

FIG. 9 shows the display unit 10 used to select an arbitrary color reproducibility in step S801.
An example of the GUI displayed on 05 is shown. The user operates the operation unit 1
By operating this GUI using 004, arbitrary color reproduction can be selected.

The GUI shown in the figure includes a "color adjustment" page. In this page, the user slides the slide bar 901 left and right using the operation unit 1004 to perform "faithful color reproduction" (first An arbitrary position between "color reproduction" and "preferred color reproduction" (second color reproduction) or a discrete position can be selected. Reproduction of skin color, green, blue, brightness, and gray can be adjusted according to the position of the selected slide bar. In this case, the mapping LUT corresponds to the LUT corresponding to the first color reproduction.
It may be calculated by a known method from the LUT corresponding to the second color reproduction, or if the slide bar is used to discretely select, an LUT corresponding to each discrete position should be prepared in advance. You may stay.

As described above, according to the image processing apparatus and the image processing method of the present embodiment, the two color reproductions generally required for the color printer, and the image displayed on the monitor are faithfully reproduced. It is possible to realize an arbitrary color reproduction between the first color reproduction and the second color reproduction that more preferably reproduces a flesh color or a memory color such as green of vegetation. As a result, the user of the color printer can obtain a desired output image only by selecting the purpose of color reproduction, and it is possible to reduce the need for color adjustment that requires knowledge and experience.

<Other Embodiments> An object of the present invention is to provide a storage medium (or recording medium) recording a program code of software for realizing the functions of the above-described embodiments.
It is needless to say that it is also achieved by supplying the system or device and the computer (or CPU or MPU) of the system or device reads and executes the program code stored in the storage medium. in this case,
The program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instructions of the program code. It goes without saying that a case where some or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing is also included.

Furthermore, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program code. Needless to say, this also includes a case where a CPU or the like included in the function expansion card or the function expansion unit performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

[0039]

As described above, according to the present invention,
An image corresponding to the color reproduction desired by the user can be easily obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of an image processing apparatus according to an embodiment of the present invention and showing a relationship with peripheral devices of the image processing apparatus.

FIG. 2 is a block diagram showing a functional configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 3 is a CIELA of an input color signal Lab corresponding to a skin color.
It is a schematic diagram which shows the conversion in B color space.

FIG. 4 is a CIELA of an input color signal Lab corresponding to green.
It is a schematic diagram which shows the conversion in B color space.

FIG. 5 is a CIELA of an input color signal Lab corresponding to blue.
It is a figure which shows the conversion in B color space.

FIG. 6 is a schematic diagram showing a relationship between a brightness component after realization of the first color reproduction and a brightness component after realization of the second color reproduction.

FIG. 7 is a schematic diagram showing conversion in the CIELAB color space of an input color signal Lab corresponding to a gray of intermediate lightness, that is, an achromatic color.

FIG. 8 is a flowchart of processing performed by the image processing apparatus according to the embodiment of the present invention.

FIG. 9 is a diagram showing an example of a GUI displayed on a display unit 1005, which is used for selecting an arbitrary color reproducibility in step S801.

FIG. 10 is a block diagram showing a basic configuration of an image processing apparatus according to an embodiment of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Osamu Yamada             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Takuya Shimada             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2C187 AF03 BF10 GA03 GA05                 2C262 AB11 AB20 AC02 BA01 BA02                       BC01 BC11 BC17 BC19 EA02                       EA05                 5B057 AA11 CA01 CA08 CA12 CA16                       CB01 CB08 CB12 CB16 CC01                       CE17 CE18 CH07 CH08                 5C077 LL19 MP08 PP32 PP33 PP36                       PP37 PQ08 PQ12 PQ23 SS05                       SS06 TT02                 5C079 HB01 HB03 HB08 HB12 LA31                       LB02 MA04 MA11 MA17 MA19                       MA20 NA03 NA17 PA03

Claims (13)

[Claims] 1. An intermediate data conversion means for converting input RGB data into first intermediate data, a holding means for holding a color conversion table corresponding to a plurality of types of color reproduction, and a desired color reproduction. A color conversion process is performed on the first intermediate data by using a color conversion table corresponding to a desired color reproduction among a plurality of types of color conversion tables held by the holding unit and held by the holding unit. And an output unit for generating and outputting output data based on the second intermediate data. 2. The image processing apparatus according to claim 1, wherein the selection unit selects any color reproduction between the first color reproduction and the second color reproduction. 3. In the first color reproduction, the color of an image on a storage medium on which an image based on the output data is printed is displayed on a display unit that displays an image based on the color and the RGB data. The image processing apparatus according to claim 2, wherein the image is reproduced in a color that is visually recognized as the same color as the image. 4. In the second color reproduction, the hues such as flesh color, blue color, green color, etc. are applied to the CIEL for the image based on the first reproducibility.
The image processing according to claim 2, wherein the color reproduction is performed in a predetermined direction in the a * and b * planes in the AB color space by a predetermined amount, and the color reproduction is brighter than the image by the first color reproduction. apparatus. 5. The image processing apparatus according to claim 1, wherein the first intermediate data is Lab data. 6. The image processing apparatus according to claim 1, wherein the second intermediate data is Lab data converted by the color conversion unit. 7. The color conversion means uses a color conversion table corresponding to a desired color reproduction, a color conversion table corresponding to the first color reproduction and a color conversion table corresponding to the second color conversion. The image processing apparatus according to claim 2, wherein the image processing apparatus is obtained by: 8. The image processing apparatus according to claim 1, wherein the output data is CMYK data. 9. The color conversion table is a mapping LU.
The image processing apparatus according to claim 1, wherein the image processing apparatus is T. 10. An intermediate data conversion step of converting input RGB data into first intermediate data by holding a color conversion table corresponding to a plurality of types of color reproduction in a memory, and selecting a desired color reproduction. And a color conversion table corresponding to a desired color reproduction among the color conversion tables corresponding to a plurality of types of color reproduction stored in the memory, using the color conversion processing on the first intermediate data. And an output step for generating and outputting output data based on the second intermediate data, and a color conversion step for generating the second intermediate data. 11. By making the information processing device read the data,
A program that causes the information processing apparatus to function as the image processing apparatus according to claim 1. 12. The information processing device reads the data,
A program for causing the information processing apparatus to execute the image processing method according to claim 10. 13. A computer-readable storage medium that stores the program according to claim 11 or 12.