Some of the filters on the Filter>Sketch menu imitate different drawing methods. When used alone, these filters work well, but they’re nothing to write home about.
I wanted to improve upon the results, so instead of applying the sketch filters to the original image in Technique 41, I applied the filters to a copied layer, and then adjusted the blending mode.
I started with a photograph of a rowboat pulled up on the shore of a lake (top).
For my first sketch, I applied the Chalk & Charcoal filter to the copied layer and set the blending mode to Lighten (middle left).
For the second sketch, I started fresh with the image and applied the Graphic Pen filter to the copied layer, and then set the blending mode to Hard Light (middle right).
The last sketch I created applied the Charcoal filter to the copied layer using navy blue as the Foreground color (resulting in a blue sketch). Then, I set the blending mode to Soft Light.
Three different filters applied using three different blending modes give very different results.
Original image Harold Davis.