A similarity index in the complex wavelet domain

It is known that in the field of image synthesis, multi-frame image processing can produce better results than just single-image enhancement techniques. Such a technique uses similarity assessment to select the images for synthesis. In this paper, we propose a new image similarity assessment index by using complex wavelet. It is found that the proposed index is robust to small rotations and translations as well as large intensity and contrast changes. Therefore, it can be widely applied in the field of image synthesis, especially high dynamic range imaging.