Leelavathi H P , Ram Manohar Nisarg
In the field of remote sensing, satellite imaging and medical imaging, images captured are often noisy, blurred and may exhibit in-sufficient resolution. Due to this instability, super imposing of Multi-sensor images has become imperative to obtain clear image, which is more appropriative for human visual perception. Image fusion has become a discipline, which demands more formal solution in different situations. Several situations in image processing require both high Spatial and high Spectral information in single image itself. This paper reviews the existing advanced pixel based Spatial domain image fusion techniques such as Average and Weighted Average method, Select Maximum, Brovey Transform, Intensity Hue Saturation(IHS), Principal Component Analysis (PCA) and Frequency domain image fusion techniques such as Fast Fourier Transform, Laplacian Pyramid, Local regression, Smoothing filter (SF), etc. Our paper is organized in the following way: Section-1: Gives introduction to image fusion. Section-2: Provides details of different fusion techniques used in both Spatial and Frequency domain. Section-3: Provides details of Measuring Techniques. Section-4: Provides comparisons of fusion methods in Spatial and Frequency domain. Finally, Section-5: Provides a Summary of the paper and its main conclusions.