Improved nonlinear diffusion denoising method based on wavelet transform and contrast sensitivity function for low-light-level images

The electron-multiplying charge-coupled device (EMCCD) is widely used in low-light-level (LLL) imaging field. In order to solve the problems of low signal-to-noise ratio (SNR) and low contrast of EMCCD LLL images under low illumination, a denoising method based on the nonlinear diffusion filter with wavelet transform and contrast sensitivity function (CSF) is proposed. Aiming at the problems existing in the P-M diffusion model, that is, the diffusion coefficient is easily disturbed by noise, and the direction affects the noise reduction process, the method introduces the wavelet transform and the CSF, then a new diffusion function is proposed to reduce the noise of LLL images. The experimental results show that, compared with other denoising methods, the proposed method has better denoising effect on EMCCD LLL images.