Patent ID: 6870955
Filing Date: 2005-03-22
Classification: H04N

Abstract:
1. A method for deciding a semi-S curve for processing tone scale of a digital image, comprising steps of: a) analyzing tone scale distribution of said image to decide a weighting value of high occurrence color; b) analyzing tone scale of said image and deciding a transition point TP for the semi-S curve through steps of: making a histogram of tone scale, making summation of samples probability F c) deciding a shadow portion color enhancement curve O-TP of the semi-S curve locating before the transition point TP, the curve O-TP passing through origin point O(0, 0), the transition point TP and a maximum downward offset point determined by a maximum downward offset D in which F L =Σ F n (n=O˜(N/2)), C 1 is a predetermined constant; and d) deciding a light portion color enhancement curve TP-E of the semi-S curve locating after the transition point TP, the curve TP-E passing through an end point, the transition point TP and a maximum downward offset point determined by a maximum upward offset D in which F H =Σ F n (n=(N+Mg)/2−Mg), C 2 is a predetermined constant; whereby, the semi-S curve composed of the curve O-TP and the curve TP-E is obtained.