Based on the wavelet transform and the relation between signal singularity and wavelet transform modular maximum, a noise removal technique is discussed.

Wavelet multi-resolution analysis method was used to detect de-noising disturbance signal, character values of the transient voltage disturbance signal were extracted more precisely.

Secondly, using locally variance estimation, a locally adaptive image-denoising algorithm was presented. Also this algorithm could be applied to the complex wavelet domain.