| 摘要 |
PROBLEM TO BE SOLVED: To compensate a digital color image for the saturation characteristics by controlling the saturation signals of colors in the digital color image corresponding to respective pixels on the basis of a calculated local gradient. SOLUTION: A prescribed tone scale function and the red, green and blue pixel values of a source image are inputted to a gradient calculating part 30 of a color difference control part 10, the local gradient of the prescribed tone scale function is calculated so as to be obtained corresponding to the pixel under processing at present, and the calculation output is inputted to a control coefficient calculating part 40. On the basis of the local gradient of the tone scale function determined by the gradient calculating part 30, the control coefficient calculating part 40 determines a scaling coefficient corresponding to a color difference signal. On the basis of that determination, a multiplying part 50 scales the respective color difference signals and outputs them to RGB reconstituting part 70 as compensated color difference signals. That RGB reconstituting part 70 controls the saturation signals of colors at respective pixel positions. |
