Abstract :Abstract— Digital image processing is a subset of the electronic domain wherein the image is converted to an array of small integers called pixels that representing a physical quantity such as scene radiance and stored in a digital memory,and processed by computer or other digital hardware. Edge detection is very useful in a number of context.Edges characterize object boundaries and are, therefore, useful for segmentation, registration, and identification of objects in scenes. Thresholding decision is the key uncertainty in the edge detection techniques. This paper explain how existing Fuzzy Logic ideas can be supplemented by the use of Automatic thresholding and generated threshold value has been used with Sobel Operator. Matlab Programming is done at different Stages.