PhotoshopElements

Trace Contour

The Trace Contour filter finds the transitions between major areas of brightness and thinly outlines them for an effect similar to the lines in a contour map. You can set the level for evaluating color values, and specify whether to outline pixels that are below (Lower) or above (Upper) that level.

Use the Info palette in grayscale mode to identify a color value that you want traced. Then enter the value in the Level text box.