Patent ID: 7113227

Claim:
A gradation correcting apparatus comprising: a maximum value detection means for detecting a maximum value of a luminance signal within a predetermined period of time, and outputting it as a maximum luminance value; a comparison means for comparing a first white threshold value, the maximum luminance value, and the luminance signal, and outputting a result of the comparison as a white comparison signal; a linear conversion means for receiving the first white threshold value, a second white threshold value, the maximum luminance value, and the luminance signal, and performing a predetermined linear conversion on the luminance signal to output a white linear-converted luminance signal; and a control means for selecting one from among the luminance signal, the second white threshold value, and the white linear-converted luminance signal, on the basis of the white comparison signal, and outputting it as a white corrected luminance signal; wherein the control means selects the luminance signal when the white comparison signal indicates that the luminance signal is equal to or smaller than the first white threshold value, selects the white linear-converted luminance signal when the white comparison signal indicates that the luminance signal is larger than the first white threshold value and equal to or smaller than the maximum luminance value, and selects the second white threshold value when the white comparison signal indicates that the luminance signal is larger than the first white threshold value and larger than the maximum luminance value.