Method for suppressing night low-illumination image noise

The invention discloses a method for suppressing night low-illumination image noise. The method comprises the following steps of: judging and finding a gain enhanced low-illumination image, performing nonlinear mapping on a noise sensitive region in the low-illumination image, performing one-time median filter on the nonlinear mapped image, and finally outputting a result image, namely the noise suppressed image. The noise of the image is suppressed by adopting a method of combining the nonlinear mapping and the median filter, so the noise of the low-illumination image is suppressed when the visibility of the original image is kept, and the picture monitoring quality of the night image is improved.