Multi-exposure & multi-focus image fusion in transform domain

Human visual system (HVS) is able to capture, process and record images with high dynamic range of luminosity, colour and focus. Unfortunately general purpose digital cameras suffer from limitations of their dynamic ranges and are thus unable to produce visually optimized photographic images. The approach used to resolve this problem is to capture images of the same scene using different exposure and focus settings and to use software based post processing technique to fuse the resulting images. Post processing techniques in general suffer from the fact that the fusion is done on already encoded images, which are decoded for the application of the pixel domain fusion techniques. The coding losses in the multiple exposure images lead to algorithmic loss in fusion, and hence would best be avoided. In this paper we propose an algorithm to perform fully automatic multi-exposure/focus image fusion in discrete cosine transform (DCT) domain. We show that fusion in DCT domain enables efficient fusion of lossless image data and the algorithm's use as an in-camera solution. This is the first attempt in addressing the problem of image fusion in transform domain. The results are compared with that of the existing state-of-the art algorithms.