JP3346862B2 - Image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for performing color correction on input image data using parameters and processing the input image data.

[0002]

2. Description of the Related Art Conventionally, once parameters for correcting the characteristics of an output device are determined, image processing is performed using the same parameters for any image. This parameter is generally determined so as to minimize the average of the square errors for all colors, but there are naturally colors with small errors and large colors among these colors. Depending on the design of the image, the color with the large error may be an important color for the design. For this reason,
In an output device that outputs many images of a person, the parameters may be determined with emphasis on skin color. However, in this case, there is a problem that an error for an image other than a person becomes large. That is, there is a problem that an optimum parameter cannot be selected depending on a picture. Also, the color reproduction range (Gamut) of the input signal
Is larger than the color reproduction range of the output device, the color reproduction range of the input signal is uniformly compressed as shown in FIG. 1, so that the colors to be accurately reproduced are compressed and the colors are shifted. There was also a problem.

[0003]

According to the present invention, a mode is selected.
An object of the present invention is to perform an optimum color correction according to a picture pattern of an image only by making a selection .

[0004]

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an image processing apparatus for performing color correction on input image data by using parameters and processes the input image data.
Center mode to optimize the color of the center part of the image in the data
And the maximum mode that optimizes the color of the part with the largest area
And the center mode and the maximum mode.
And operation means for selecting one of the, Tsu by the said operation means
Color to determine the optimal color according to the selected mode
Determining means and the optimized color determining means
Characterized by comprising a parameter calculating means for calculating the parameters for color correction based on optimization color
And

[0006]

[0007]

[0008]

According to the present invention, in an image in input image data,
The center mode that optimizes the color of the heart and the maximum area
The maximum mode is set to optimize the color of a certain part,
Among the set modes, the center mode and the maximum
Select one of the modes by operating
Parameters are calculated according to the color and the color is corrected.
Only by selecting a mode with the operation means, it is possible to perform optimal color correction according to the picture pattern of the image.

[0009]

[0010]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 2, an overall configuration diagram of an embodiment of the present invention will be described. The color correction means 100, which is a color correction circuit, performs color correction on the input color signal according to the set parameters, and outputs an output color signal. The output unit 101, which is a printer, records an image on transfer paper based on the input output color signal. The parameter calculating means 102, which is a parameter calculating circuit, sets the specified optimized color as a fixed point as shown in the color space of FIG. 3, and sets the input signal Gamut and the preset signal based on the fixed point. Gam of output device
ut, the color reproduction range is compressed, and the parameters are calculated, and the parameters are set in the color correction means 100. Optimized color determination means 103 which is an optimized color determination circuit
Optimizes the color of the central part of the image as shown as the face part in FIG. 4 or the color of the part with the largest area in the image as shown as the blue sky part in FIG. 5 according to the instruction. The color is determined, and an optimized color is instructed to the parameter calculation means 102. An operation means 104, which is an operation panel, is a switch for selecting a center mode in which the color of the central portion of the image is the optimum color and a maximum mode in which the color of the portion having the largest area is the optimum color. The center mode is normally selected, and one of the modes is instructed to the optimization color determination means 103.

The control of the optimized color determining means 103 will be described with reference to the flowchart of FIG. S601 is a step of detecting the designated mode, and determines whether the mode is the center mode. S602 is a step in which when the central mode is detected in S601, the color of the central portion of the image is determined to be the optimized color. S
Step 603 is a step of creating a histogram of the number of colors used in the image when it is detected in S601 that the mode is not the center mode, that is, when the mode is the maximum mode. S604 is a step of determining the color indicating the maximum value (the color having the largest area in the image) in the histogram and making it the optimized color. S605 is a parameter
This is a step of instructing the data calculation means 102 on the optimized color.

The control of the parameter calculation means 102 will be described with reference to the flowchart of FIG. In step S701, a predetermined input signal Gamut and an output device Gamut are set.
This is the step of reading. S702 is a step of reading the specified optimized color. In step S703, the optimized color is set as a fixed point as shown in the color space of FIG. 3, and based on the fixed point, the input signal Gamut and the output device Gamut are output.
This is a step of compressing the color reproduction range from t. S7
Step 04 is a step of calculating parameters for correction determined according to the compression of the color reproduction range. S705
Is a step for setting parameters in the color correction means 100. As a method of compressing the color reproduction range, there is a method of uniformly compressing the brightness and saturation while maintaining the hue, and a method of elastically deforming the color reproduction range assuming that the color reproduction range is an elastic body. A method may be used. Also, the parameter
As a method of calculating the data, a least square method with a constraint condition that the fixed point has a minimum error can be considered.

[0014]

As described above, according to the present invention,
Just by selecting the mode, it is possible to perform optimal color correction according to the picture pattern of the image.

[0015]

[0016]

[Brief description of the drawings]

FIG. 1 is a model diagram showing conventional color gamut compression.

FIG. 2 is a block diagram showing the overall configuration of the present invention.

FIG. 3 is a model diagram showing compression and the like of a color reproduction range according to the present invention;

FIG. 4 is a diagram showing a case where a center mode is selected.

FIG. 5 is a diagram showing a case where a maximum mode is selected.

FIG. 6 is a flow chart showing control of an optimized color determining means.
G

FIG. 7 is a flowchart showing control of a parameter calculating means.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 color correction means 101 output means 102 parameter calculation means 103 optimized color determination means 104 operation means 105 operation panel

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Claims (1)

(57) [Claims] 1. An image processing apparatus for performing color correction using parameters on input image data for processing, wherein a color of a central portion of an image in the input image data is optimized.
Center mode and maximum mode that optimizes the color of the area with the largest area
When sets a, the center mode and operation means for selecting one of a maximum mode, optimum color depending on the selected mode I by the said operating means
And optimization color determining means for determining an optimized color group is determined by the optimization color determining means
That it comprises a, a parameter calculating means for calculating the parameters for color correction Zui image processing apparatus according to claim.