ADAPTIVE GAMMA PROCESSING OF THE VIDEO CAMERAS FOR THE EXPANSION OF THE DYNAMIC-RANGE

We have developed a new method for the expansion of the dynamic range of the video camera. A variable and nonlinear gamma characteristic is applied to the input image depending on the distribution of the lumina nce. The gamma characteristic is decided so as to amplify the luminanc e of the dark pixels and to preserve the contrast of the bright pixels for the back-lit objects. The output luminance equals the input lumin ance for the front-lit objects. We have established the decision rule of the gamma characteristic using the learning algorithms of the neura l networks in order to make the decision rule coincide with the human vision. The effect of our new method is the expansion of the dynamic r ange by 9.6 dB. We have developed a new structure for the implementati on of the gamma decision rule. It consists of a cascade connection of RAMs and its scale is less than 1/100 than the conventional structure with a single RAM. We have implemented the adaptive gamma processing i n a consumer video camera.