Image enhancement based on the stationary wavelet translation whit rotation, shift and scale invariance

Since traditional discrete orthonormal wavelet transform being more sensitive to the original position of signal, a stationary wavelet transform which possess the properties of rotation, shift and scale invariance is proposed. The image is transformed to polar coordinates, and confirming the principal axis orientation to adopt orientation energy function, then rotating the principal axis of image to the level orientation to gain the unifying image in the orientation. By reforming the image and rotation, shift and invariance to the wavelet bases, thus the influence of shift and scale is eliminated, renormalized image projected on to the multi-resolution subspaces spanned by a set of shifted and dilated orthonormal wavelet basis function to get stationary translation and scale invariance. The non-linear gain operator enhances the image, combining Otsu adaptive optimization threshold estimation function. Experimental result show that the method can better reserve the image edge and enhance the image at the same time, and being a kind of valid method of the image enhancement.