Research on the Digital Test of TV Camera's Signal to Noise Ratio

This paper presents a quick and objective signal-to-noise ratio (SNR) digital test method for TV camera. Through imaging an overall white transparent test chart with high evenness illumination, the fluctuation of the output video signal reveals the existence of the noise. Using the frame grabber to digitalize the analogue video signal to digital image, the noise can be separated and stood out by digital high pass filter and its amplitude is calculated as root-mean-square (RMS) value. Because the frame grabber introduces additional quantization noise to the digital image, the SNR of the original video signal can be calculated after correcting the quantized noise. The SNR digital test system can get an objective measurement as well as high repeatability, and the results obtained are consistent with those produced by industry standard instrument, so it can be used as a replaceable method for camera's SNR testing.