When the rocket or missile launches

the ground testing images are interfered seriously by smoke. The research on the weakening of smoke in images is very important in the ground testing image preprocessing. This paper firstly discusses smog removing in the frequency domain

and it proposes a new homomorphic filtering method. Then it proposes Weighing Wavelet Coefficient approach weakening smoke on account of the multi-resolution and space-frequency nature of the Wavelet Transform. Finally it adopts five different objective appraisal methods to evaluate the disposed images. Experimental results show that the two proposed approaches are more effective on smog weakening than the other three.