Wavelets for Image Fusion

In thi s chapter we pres ent some recent resuits on the use of wavelet al­ gorithms for imag e fusion . The chapt er starts with abrief introduction of imag e fusion . The following sections describe three different wave­ let transforms and the way they can be employed to fuse 2-D images. These include: th e discrete wavelet transform (DWT); th e dual -tree complex wavelet transform (DT-CWT); and Mallat's discrete dyadic wavelet tr ansform (DDWT), which can also be used to compute a multi­ scale edge representation of an image . The three wavelet fusion schemes are compared both qualitatively and quantitatively and are applied to fuse multifocus , remote sensing and medical (CT and MR) image s. The experimental compar ison clearly shows th at DT-CWT fusion techniques provide better results than their DWT counterparts. In addition, the use of DT-CWT gives control over dire ctional information in the im­ ages, while the use of multiscale edge fusion methods provides cont rol over the edge information to be retained in the fused output. The chap­ ter concludes with a discussion about the strong points and difficulties associated with each of th e proposed wavelet fusion schemes and with some ideas for future research .