Efficiency of wavelet coefficients thresholding techniques used for multimedia and astronomical image denoising

This paper deals with image denoising based on the wavelet transform realized by Mallat algorithm and À trous algorithm. The effectiveness of global and subband thresholding techniques are studied on multimedia and astronomical images contaminated by Gaussian noise. Experimental results on several testing images are compared with each other from two objective quality aspects (PSNR, RMSE). Astronomical image denoising techniques differ from those used for multimedia images, because astronomical data are processed by computers and are not evaluated by humans. Thus we show especially the difference between quality criteria related with both types of images after denoising. In case of astronomical data, important scientific criteria as stellar magnitude and FWHM (Full Width at Half Maximum) changes are studied in processed images after noise removal.