Proc. SPIE 6816, Sensors, Cameras, and Systems for Industrial/Scientific Applications IX
Complementary metal oxide semiconductors, Image processing -- Digital techniques, CCD cameras -- Calibration
We present data for the dark current of a commercially available CMOS image sensor for different gain settings and bias offsets over the temperature range of 295 to 340 K and exposure times of 0 to 500 ms. The analysis of hot pixels shows two different sources of dark current. One source results in hot pixels with high but constant count for exposure times smaller than the frame time. Other hot pixels exhibit a linear increase with exposure time. We discuss how these hot pixels can be used to calculate the dark current for all pixels. Finally, we show that for low bias settings with universally zero counts for the dark frame one still needs to correct for dark current. The correction of thermal noise can therefore result in dark frames with negative pixel values. We show how one can calculate dark frames with negative pixel count.
William C. Porter ; Bradley Kopp ; Justin C. Dunlap ; Ralf Widenhorn and Erik Bodegom, "Dark current measurements in a CMOS imager", Proc. SPIE 6816, Sensors, Cameras, and Systems for Industrial/Scientific Applications IX, 68160C (February 29, 2008); doi:10.1117/12.769079