Basic Description: Edge uses a variety of edge detection algorithms to highlight sharp contrast changes in an image. The resulting image is binary, with edges indicated as value = 1 and all other pixels with value = 0.
Technical Details: Refer to descriptions of each algorithm.
Instructions: After choosing a selection method and making your selection on the survey, choose an algorithm and enter the parameters using the instructions below.
 Canny
Canny is based on the well-known Canny edge detection algorithm. A higher Threshold will return fewer edges at a given scale. Sigma determines the size of the Gaussian filter used to smooth the image before edges are extracted.
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 Log
LoG using the zero-crossings of the Laplacian of Gaussian filter to detect edges in the selected tiles. A higher Threshold will return fewer edges at a given scale. Sigma determines the size of the Gaussian filter used to smooth the image before edges are extracted.
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 Prewitt
Implements the standard directional Prewitt edge detection algorithm.
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 Sobel
Implements the standard directional Sobel edge detection algorithm.
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 Roberts
Implements the standard Roberts edge detection algorithm.
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 Zerocross
Zerocross using the zero-crossings of the Laplacian filter to detect edges in the selected tiles. A higher Threshold will return fewer edges. This choice is similar to LoG but does not allow smoothing.
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