Image fusion refers to the technique of integrating information from two or more images to obtain a single image retaining important features from each. The new image obtained after fusion is improved with respect to image quality, more suitable for human and machine perception and various image processing tasks like image analysis, segmentation, object recognition etc. Different fusion methods have been proposed in literature, including multi-resolution analysis. This paper is based on multi-resolution image fusion using wavelet transform. The key step in image fusion based on wavelet transform is that of wavelet coefficient combination in an appropriate way in order to obtain the best quality in the final image. Various coefficient combination methods have been proposed in the literature. This paper presents comparative analysis of a few selected methods , which are commonly used, for the fusion of multi-focus images and medical images.