A multi-modal automatic image registration technique based on complex wavelets

Image registration is considered one of the most fundamental and crucial pre-processing tasks in digital imaging. This paper describes a fast multimodal automatic image registration algorithm that handles the alignment of IR and visible images. A multiresolution approach based on dual tree-complex wavelet transform is employed to speed up the process. At the coarsest level, an accurate registration estimate for higher levels is achieved, using edge detection and cross correlation. Mutual information, on the other hand, is applied at higher levels as a matching criterion applied to the six orientation bands of the complex wavelet. The process is completely automatic, and was tested on several sets of synthetic and real data. Experimental results show that the proposed technique exhibits better accuracy than DWT-based algorithms for uni and multi-modal cases.