1. An image denoising method, comprising: performing preliminary denoising processing of an acquired image to be processed, so as to obtain a preliminarily denoised image; calculating a residual quantity corresponding to a central pixel of each unit area in the image to be processed according to numerical values of specific energy parameters to which the image to be processed and the preliminarily denoised image correspond, respectively; and using the residual quantity to calculate a weight matrix corresponding to each unit area, and performing a non-local mean value calculation on the image to be processed according to the weight matrix to realize the denoising processing of the image to be processed.