[Paper] Low-light Color Reproduction by Selective Averaging in Multi-aperture Camera with Bayer Color-filter Low-noise CMOS Image Sensors

Abstract

We have demonstrated effectiveness of the selective averaging with a multi-aperture camera for reducing image sensor noise such as random telegraph signal (RTS) noise and large dark current shot noise. In this paper, noise reduction capability in color reproduction with the proposed method is studied by simulation, where we assume an ultra-high-sensitivity 2 x 2-aperture color camera. In the prototype camera, which is being developed, low-noise Bayer color-filter 0.18um CMOS image sensors based on the folding-integration and cyclic column ADCs with 1280 x 1024 effective pixels are utilized. The synthetic F-number is 0.6. Simulation shows that the effective noise in terms of the peak of noise in histogram is reduced from 1.44 electrons to 0.74 electrons, and RTS noise and large dark current shot noise are successfully removed. Color reproduction errors are quantitatively evaluated. The root-mean-square errors of blue, green, red, and white in the CIE-xy color space becomes approximately a half after the selective averaging.