| Keyboard Shortcut | Menu Shortcut | Menu Location |
| Shift+E | Alt+R, A | Raster -> Nonlinear Edge |
The Nonlinear Edge command traces boundaries between colors. The results from Nonlinear Edge are often smoother than the results of the Linear Edge command.
Original color image
Color image after Nonlinear Edge command
Nonlinear Edge image after cleaning up with Threshold and Remove Noise