If you combine the Find Edges filter and the Overlay blending mode can produce a high-contrast sketch effect that seems to work with many types of images.
This recipe includes multiple Overlay layers, which boost contrast, so the recipe works particularly well with low-contrast images. In the recipe, I have used 3 Overlay layers—you can use more or fewer, though but, beware, more than 3 can produce excessive contrast. If the result is too harsh, add some Gaussian Blur. (About 3 or 4)
- In the Layers palette, duplicate the original image layer by dragging the background layer onto the “Create a new layer” icon, or use Ctrl J.
- Using the pull-down blending mode menu in the Layers palette,(Which normally shows the word Normal) change the duplicate layer’s blending mode to Overlay (or use the shortcut Alt/Opt-Shift-O) and rename it “Overlay 1.”
- Reduce the Overlay 1 layer’s opacity to 60%.
- Apply Filter > Stylise > Find Edges to the Overlay 1 layer. Add some Gaussian blur at this stage.
- Use Ctrl J to duplicate the Overlay 1 layer. Name the new layer “Overlay 2.”
- Use Ctrl F to apply Filter > Stylise > Find Edges to the Overlay 2 layer.
- You can repeat steps 5 and 6 if you like, however, it adds more contrast and the image gets darker. I have found that this method does not work for all pictures, it makes some seem absolutely gaudy whilst one application plus a Gaussian blue sometimes works and gives a good end result. This setup is very much a matter of experimenting. See what works best for you. Try a few variations.
