Patent ID: 8107123

Claim:
A tone correction apparatus for carrying out tone correction upon dividing one image area of a digital image into a plurality of local regions, comprising: an average luminance calculation part for obtaining average luminance of each of said local regions of said digital image; a correction amount calculation part for comparing the average luminance of each of said local regions and a predetermined value defined from a range of all luminance tone levels, thereby obtaining a direction of correction and a correction amount of the average luminance of each of said local regions to be as a first correction amount for each of said local regions; an interpolation part for obtaining a second correction amount for each pixel by spatial interpolation with respect to said first correction amount by using positions of each pixel located between adjacent local regions; and a tone conversion part for selecting for each pixel, one tone conversion function from among a previously prepared plurality of tone conversion functions by using said second correction amount, thereby correcting luminance of each pixel.