Objective To study the problem of eliminating the noises introduced during image collection process of linear array CCD. Methods Through experiments, it was found that Gaussian noise and salt pepper noise were usually introduced into the detection system of prints. Wavelet transforms and Gaussian-median mixed algorithm were used in the denoising processing. Results Through comparison with different methods, the feasibility of these two methods were proved. Conclusion Wavelet transforms was good in removing the Gaussian noise, while Gaussian-median mixed algorithm achieved good results in eliminating slat pepper noise because it could keep the details of the images during denoising.