Image Fusion is the process of combining information from two or more images of the same scene taken at the same instant or at different instants to provide more detailed images than the individual images separately. Image fusion has applications in different areas like commercial, military, medical, remote sensing, urban development, agricultural, etc. We present here the different image fusion techniques and algorithms including PCA, Wavelets, Shearlets and Noiselets. © 2017 Elsevier B.V., All rights reserved.