Research on a method to extend dynamic range of CMOS APS

Dynamic range is a very important figure of merit to an imaging system since it decides the range of brightness we can observe. The paper first introduces the design of a CMOS sensor, which achieves high dynamic range by its dual slope response. And then a model is established to illustrate how the dual slope response works. A method to reconstruct the acquired image from multi-slope response to linear response over fully extended dynamic range is also developed and analyzed by simulations and experiments. In addition, the reconstruction error is discussed. Experimental tests were carried out using the extended dynamic range CMOS camera working in dual slope mode, and then the image was restored from dual slope response to linear response over fully extended dynamic range. The results show a favorable aspect of the CMOS imager with dual slope response and data restoration method in large dynamic range imaging.