Abstract:This paper aiming at the dynamic range and signal-to-noise ratio (SNR) indexes of electronic endoscopes, this article analyses the sources of image noise by CMOS structure and the adjusting of ISO sensitivity, and obtains that the dynamic range and signal-to-noise ratio decrease with the increase of ISO sensitivity, and the maximum signal-to-noise ratio and dynamic range are 40.712 dB and 338.8 respectively when the ISO sensitivity is 100. Increasing the input luminance can significantly reduce the interference of photon shot noise on the image signal-to-noise ratio, which provides a reference for the development, analysis, quality detection and modification of electronic endoscope products.