Use the Gradient filter to detect edges that are present in the image. You'll find the filter in the Process > Morphological Filter menu.
See also
Overview - Morphological Filter
Working with morphological filters
Settings for the filter
Here you'll find information on how you can set the shape and size of the morphological filter.
The dialog box that is opened when you use an image processing operation is made up in the same way for every operation. Click here to switch to a description of this dialog box.
Exactly what happens?
This filter is a combination of the Erosion filter, the Dilation filter, and an arithmetical subtraction. The source image is first eroded, which filters fine disturbance particles out of the image, and removes the object's outer edges. The source image is then dilated. The dilation removes small holes, as well as irregularities on the edges. Finally, the eroded image is subtracted from the dilated image.
The illustration demonstrates the way the filter works on a simple structure. In the source image (1) you see the original structure. After the filtering has taken place (2) the edges of the structure are clearly recognizable. The Laplace filter (3) produces a comparable result. The lines created by the Laplace filter are typically thinner than those of the Gradient filter.
Comparison with other filters
The way this filter works is similar to the way the edge detection filters work. You'll find an overview of the available edge detection filters here.
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