Patent ID: 7292370

Claim:
An image processing device comprising: a converting section for converting image data according to a conversion characteristic of gradation conversion of the image data; a designating section for designating a modification to the conversion characteristic of gradation conversion of the image data; and a control section adapted to control the converting section such that a gradation of the image data is converted in accordance with the modified conversion characteristic, wherein the control section is further adapted to correct changes, which are imposed by the modification to the conversion characteristic on the difference values between each color component of a pixel in the image data and the gray level of that pixel, by reconverting the image data which is converted by the converting section, or adjusting the modified conversion characteristic of the converting section, wherein the control section reconverts the image data which is converted by the converting section, or adjusts the modified conversion characteristic, such that the difference values between each color component of a pixel and the gray level of that pixel of the image data remain substantially unchanged as compared to before the image data is converted by the converting section, and wherein the control section reconverts the image data in accordance with a conversion characteristic which satisfies the following expressions: R2′−(R2′+G2′+B2′)/3 is substantially equal to R2−(R2+G2+B2)/3, G2′−(R2′+G2′+B2′)/3 is substantially equal to G2−(R2+G2+B2)/3, B2′−(R2′+G2′+B2′)/3 is substantially equal to B2−(R2+G2+B2)/3, wherein R 2 ′, G 2 ′, B 2 ′ are color component values of respective pixels of image data when image data, whose gradation has been converted in accordance with the modified conversion characteristic, is converted, and R 2 , G 2 , B 2 are color component values of respective pixels of image data when image data, whose gradation has not been converted, is converted.