Comparative analysis of color architectures for image sensors

We have developed a software simulator to create physical models of a scene, compute camera responses, render the camera images and to measure the perceptual color errors (CIELAB) between the scene and rendered images. The simulator can be used to measure color reproduction errors and analyze the contributions of different sources to the error. We compare three color architectures for digital cameras: (a) a sensor array containing three interleaved color mosaics, (b) an architecture using dichroic prisms to create three spatially separated copies of the image; (c) a single sensor array coupled with a time-varying color filter measuring three images sequentially in time. Here, we analyze the color accuracy of several exposure control methods applied to these architectures. The first exposure control algorithm (traditional) simply stops image acquisition when one channel reaches saturation. In a second scheme, we determine the optimal exposure time for each color channel separately, resulting in a longer total exposure time. In a third scheme we restrict the total exposure duration to that of the first scheme, but we preserve the optimum ratio between color channels. Simulator analyses measure the color reproduction quality of these different exposure control methods as a function of illumination taking into account photon and sensor noise, quantization and color conversion errors.