Script-Fu -> Pastel
This is a an adjustable script to made an image look like it was drawn/painted in pastels. The "sketch amount" and "sketch length" can change the look and feel of results quite a bit, and since the effect can be left on a separate layer when complete (uncheck the "Flatten Image" box) you can set that layers opacity to lessen the effect if desired.
Pastel Dialog
Original Image
"the Lovers" by Pablo PicassoResult 1:
Default Settingslayer dialog:
to adjust results of pastel scriptIf you choose NOT to flatten the image when complete -- you can adjust the layer opacity to tone the effect down as needed. You can choose from the image menu:
WINDOWS > DOCKABLE DIALOGS > LAYERS
(or Ctrl + L)
There you can set the layer opacity. In the example I drag the slider to 25% . . . the "Pastel layer" was already selected.