The HMT method applied in natural image denoising was thoroughly studied. T
he HMT method was compared with others under different conditions, such as
different complexity of the texture, different-type noise and different tra
nsform domain. Some key conclusions were obtained. First, the method in tra
nsform domain is better than the traditional one which is not in transform
domain. Second, the performance of HMT in the DCT domain is similar to that
in the wavelet domain. Third, when the noise is white, result of HMT is ex
cellent. However, when the noise is related to the image itself, the perfor
mance is determined by the complexity of the texture, as well as the noise
density.