1. An ultrasound diagnosis apparatus comprising: a decomposing unit configured to decompose ultrasound image data into low-frequency decomposed image data and high-frequency decomposed image data at each of a predetermined number of hierarchical levels, by performing a hierarchical multi-resolution analysis; a diffusion filter unit configured to apply, at a lowest hierarchical level of the predetermined number of hierarchical levels, a non-linear anisotropic diffusion filter to the low-frequency decomposed image data and the high-frequency decomposed image data at the lowest hierarchical level, configured to apply, at each of the hierarchical levels higher than the lowest hierarchical level, a non-linear anisotropic diffusion filter to data output from a hierarchical level immediately underneath that has been reconstructed by performing a multi-resolution analysis and to the high-frequency decomposed image data at that hierarchical level, and configured to generate, for each of the hierarchical levels, edge information of a signal either from the low-frequency decomposed image data at the lowest hierarchical level or from the data output from the hierarchical level immediately underneath; an adjusting unit configured to adjust a signal level of the high-frequency decomposed image data for each of the hierarchical levels, based on the edge information obtained at each of the hierarchical levels; and a reconstructing unit configured to obtain corrected data of the ultrasound image data by hierarchically performing a multi-resolution synthesis on data output from the diffusion filter unit and data output from the adjusting unit that are obtained at each of the hierarchical levels.