1996 Volume 8 Issue 6 Pages 1154-1159
Auto exposure (AE) is an important function of video cameras to adjust the image luminance. In this paper, the exposure control systems of the AE using color information are discussed. Current AE systems detect the backlighting and excessive frontlighting, and conduct the exposure control putting emphasis on the main object by compensating the exposure. This backlighting / excessive frontlighting compensation is characterized by adjusting the luminance of the main object where it is appropriate, causing the background to become worse. However, in the AE systems which have been proposed so far, the compensation amount is determined according to the degree of backlighting and excessive frontlighting, regardless of the importance of the background. Since these AE systems control the exposure obtaining information from the luminance signal, judging the importance of the background with only luminance information is difficult. The proposed exposure control system employs "hue" and "chroma" of pixels to derive the importance of the background, and determines a compensation amount by fuzzy reasoning.Simulations of AE are carried out for the conventional system and proposed one. The performance of each system is tested through the assessment experiments of human subjects for image samples of simulation results, and the proposed system is shown to be efficient for AE.
