Image processing method and apparatus, and color conversion table generation method and apparatus

An apparatus for generating a color conversion table, comprising:

• storage device which stores first and second images, pixel values of which are expressed on an N-dimensional color space;
• generation device which generates an N-dimensional color conversion table on the basis of differences between pixel values of corresponding pixels in the first and second images;
• and
• adjustment device which adjusts generation of table values of the color conversion table by said generation device so that a change amount of a pixel value defined by the color conversion table generated by said generation device does not exceed a predetermined value;
• wherein when a difference between grid point data of the color conversion table generated by said generation device and a reference table is not less than a predetermined value, said adjustment device adjusts the grid point data of the color conversion table;
• and
• wherein let (A0, A1, A2, . . . , AN) be grid point data of the color conversion table, (B0, B1, B2,. . . , BN) be grid point data of the reference table, and Diff be the difference, and when the difference Diff given by:
• Diff=√(A0−B0)2+(A1−B1)2+(A2−B2)2+ . . . +(An−Bn)2
• is larger than a predetermined threshold value T, said adjustment device multiplies the grid point data by a value obtained based on the threshold value T and the difference Diff.

An apparatus for generating a color conversion table, comprising:

• storage device which stores first and second images, pixel values of which are expressed on an N-dimensional color space;
• generation device which generates an N-dimensional color conversion table on the basis of differences between pixel values of corresponding pixels in the first and second images;
• and
• adjustment device which adjusts generation of table values of the color conversion table by said generation device so that a change amount of a pixel value defined by the color conversion table generated by said generation device does not exceed a predetermined value;
• wherein when a distance between the pixel values of the corresponding pixels on the color space exceeds a threshold value, said adjustment device adjusts the difference between the pixel values of the corresponding pixels on the basis of the distance and the threshold value;
• and
• wherein let (A0, A1, A2, . . . , AN) be pixel values in the first image, (B0, B1, B2, . . . , BN) be pixel values of corresponding pixels in the second image, and Diff be the distance, and when the distance Diff given by:
• Diff=√(A0−B0)2+(A1−B1)2+(A2−B2)2+ . . . +(An−Bn)2
• is larger than a predetermined threshold value T, said adjustment device multiplies differences between the corresponding pixels for respective components by a value obtained based on the threshold value T and the distance Diff.

An image processing method comprising:

• inputting an image sensed by image sensing device;
• acquiring at least one pixel value pair based on a source pixel value obtained from an image and a destination pixel value obtained from an image;
• determining an image processing parameter for converting one pixel value of the pixel value pair into the other pixel value of said pixel value pair, on the basis of the acquired pixel value pair;
• registering the determined image processing parameter;
• and
• converting pixel values of an input image input by said input device on the basis of the registered image processing parameter, and outputting a converted image as an output image.

An apparatus for generating a color conversion table, comprising:

• storage device which stores first and second images, pixel values of which are expressed on an N-dimensional color space;
• generation device which generates an N-dimensional color conversion table on the basis of differences between pixel values of corresponding pixels in the first and second images;
• and
• adjustment device which adjusts generation of table values of the color conversion table by said generation device so that a change amount of a pixel value defined by the color conversion table generated by said generation device does not exceed a predetermined value;
• wherein when a distance between pixel values before and after conversion by the color conversion table generated by said generation device exceeds a threshold value, said adjustment device adjusts a corresponding table value in the color conversion table;
• and
• wherein let (A0, A1, A2, . . . , AN) be pixel values before conversion by the color conversion table, (B0, B1, B2,... , BN) be pixel values after conversion, and Diff be the distance, and when the distance Diff given by:
• Diff=√(A0−B0)2+(A1−B1)2+(A2−B2)2+ . . . +(An−Bn)2
• is larger than a predetermined threshold value T, said adjustment device updates the color conversion table by multiplying the corresponding table value by a value obtained based on the threshold value T and the distance Diff.

An apparatus for generating a color conversion table, comprising:

• storage device which stores first and second images, pixel values of which are expressed on an N-dimensional color space;
• generation device which generates an N-dimensional color conversion table on the basis of differences between pixel values of corresponding pixels in the first and second images;
• and
• adjustment device which adjusts generation of table values of the color conversion table by said generation device so that a change amount of a pixel value defined by the color conversion table generated by said generation device does not exceed a predetermined value.