AUTOMATIC TONE CONTROL METHOD BY CONTRAST GAIN CONTROL OF EDGE

摘要

PROBLEM TO BE SOLVED: To compress the dynamic range of an input picture and to appropriately reproduce the input picture in a smaller output display medium by extracting a minute signal and a rough signal from the input picture, detecting a rough scale edge, generating a contrast gain control signal and correcting a minute signal in accordance with the contrast gain control signal. SOLUTION: A tone scale curve module 80 calculates the tone sale curve of an input picture I and generates a picture I' which is tone scale-processed. An edge signal and a minute signal are extracted from a differential picture D obtained by subtracting the picture I' from the input picture I. The edge signal is modulated by a contrast gain control signal generated by a contrast gain control module 90. Thus, the edge signal and the minute signal of the differential picture D are contained in output D' from a reconstitution filter bank 70. The output D' is synthesized with the picture I' and an output picture IOUT is generated.