COMBINING SPATIAL AND FREQUENCY FILTERING TO REDUCE SPECKLE NOISE IN IMAGES

. The paper considers a comparison of various combinations of spatial and frequency filters for suppressing speckle noise of images belonging to different types. The main characteristics, advantages and disadvantages of popular spatial and frequency filters used for noisy image processing are presented. Four combinations of filters created by applying the average and median filters and the wavelet-based filters are considered. The results of machine experiments have shown the advantage of the wavelet median filter compared to other filter combinations according to the criteria of peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM).