In Recent Years, Monitoring Of Coral Reef Status And Health Are Done With The Assist From Image Processing Technique. Since Underwater Images Are Always Suffer From Major Drawbacks, Research In This Area Is Still Active. In This Paper, We Propose To Use Edge Based Segmentation Where We Modify The Original Canny Edge Detector And Then Use The Blob Processing Technique To Extract Dominant Features From The Images. We Conduct The Experiments Using Images That Are Extracted From Video Transect And The Results Are Promising For Estimating Coral Reefs Distribution.