摘要:Edges are prominent features that specify the boundary between two different regions in animage. Edge detection algorithm reveals the sharp discontinuities points. This processor reduces the uselessinformation while preserving the significant structure. There are a lot of different methods to detect the edge ofimages that have been proposed over the past years. However, they cannot still find an algorithm with a strongresponse to edges. This paper reviews three main categories of edge detection techniques includingdifferentiation, Wavelets transform, and Gabor Filters. In the study, the advantages and disadvantages of thesealgorithms are investigated and compared. Some of the researchers have combined these methods with eachother and their effects have usually shown better results. After research about these methods we concluded that,the third category is appropriate for real images containing several noises. These groups also have resemblanceto human visual system and can extract local feature such as edges, and the tissues of images