SYSTEM AND METHOD FOR DIGITAL IMAGE TONE MAPPING USING ADAPTIVE SIGMOIDAL FUNCTION BASED ON PERCEPTUAL PREFERENCE GUIDELINE

摘要

PROBLEM TO BE SOLVED: To faster generate a reproduced image fitting user's preference at a lower cost in an image reproduction system. SOLUTION: An adaptive image tone mapping curve (170) based on perceptual preference guidelines is generated as a sigmoidal function. The sigmoidal function parameters (150) (slope and shift) are determined by original image statistics (149). Tone curves (170) generated for different images each have a smooth sigmoidal shape, so that a tone mapping process does not change an image histogram shape drastically. A sigmoidal tone curve (170) calculation can be implemented efficiently by using simple arithmetic operations by pre-calculating and storing various factors used in the calculation of alpha and beta and by generating a pair of fixed tone curves (158) with two extreme slopes and interpolating between the curves (158).