On Wide Dynamic Range Tone Mapping CMOS Image Sensor

Abstract

The dynamic range of a natural scene often covers over 6 decades of intensity from bright to dark areas. Typical image sensors, however, have limited ability to capture this dynamic range available in nature. Even after designing specific wide dynamic range (WDR) image sensors, displaying them on conventional media with limited ability requires computationally complex tone mapping.This paper proposed a novel CMOS pixel which can capture and perform tone mapping during data acquisition. The pixel requires a reference voltage to generate tone mapped response. A number of different reference signals are proposed and generated which can perform WDR operation. Nevertheless, fixed pattern noise (FPN) effects the performance of these pixel. A pixel model with simple parameter extraction procedure is described for a typical tone mapping operator. This model is then used to obtain a simple procedure for pixel calibration leading to reduced FPN. The new proposed pixel response is able to capture upto 6 decades of light intensity and reported FPN correction procedure produces 1% of FPN contrast error.