Edge

This transformation lets you locate, lighten, or darken edges in an image.

Amount

The amount control lets you control how much of the edge transformation is applied to the input image. You can apply a percentage of the transformation to the entire image, or you can specify an amount mask to restrict the effects of the transformation to only part of the input image.

Color Space

This control lets you select the HSV, HSL, or RGB color space. If you select RGB, then the red, green, and blue channels of the input image are edge enhanced separately and combined in the output image. If you select HSV or HSL, then only the V or L channel is affected, leaving the hue and saturation intact.

Method

This control lets you select from three different edge detectors.

Roberts -- produces thinner, less distinct edges

Sobel -- produces thicker, more distinct edges

Laplacian --  works by computing the difference between a pixel and its eight nearest neighbors -- produces the thinnest edges

Action

This control lets you select how the edge information is used to modify the input image.

Compute -- causes the result of the edge transformation to be the output image.

Lighten -- causes edges detected in the input image to be lightened.

Darken -- causes edges detected in the input image to be darkened.

Strength

This slider lets you select increase or decrease the intensity of the edges, making them more or less visible.