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Length/Width Ratio Test for Fish Classification

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  • Computer Science


Connexions module: m11768 1 Length/Width Ratio Test for Fish Classification ∗ Kyle Clarkson Jason Sedano Ian Clark This work is produced by The Connexions Project and licensed under the Creative Commons Attribution License † Abstract This test determines whether a fish is a salmon or a trout, or neither based on the length and width of the fish One simple way to tell different fish apart is due to their ratio of length to width. For every species of fish, that ratio is essentially the same. On reason salmon are unique in that regard is because during spawning season, they grow wider and thus their length to width ratio becomes much smaller (approximately 2:1 or 3:1). Other fish, such as steelhead trout, which maintain a much more sleek, approximately 3:1 to 4:1 length to width ratio even during spawning season. This test is done using primarily the Canny Edge Detection method which is performed by Matlab using the command edge. It takes the image of the fish and finds an outline of it. ∗ Version 1.1: Dec 18, 2003 1:52 pm -0600 † Connexions module: m11768 2 Canny edge detection Image Figure 1: The Fish image after the canny edge detection is run on it. 1 Canny Edge Detection Image edges contain strong contrasts in intensity. The Canny Edge Detector tries to find only true edges by only selecting localized edge points and only responding once to a single real edge. The Canny method also filters noise with a convolution mask built through Canny's algorithm. The edge detector then uses the gradient of the image and summing along the x direction and y direction to obtain the edge value. Direction of the edge is easily determined by looking at each directions value and seeing which one is larger. However, it is important to test for errors when one direction is zero, so Canny looks at the angle between the x-direction and y-direction. Canny also uses supp

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