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.
Original Image"the Lovers" by Pablo Picasso
Result 1:Default Settings
layer dialog:to adjust results of pastel script
If 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.
result modified:opacity set to 25%
Sketch length Modified:sketch length increased
Sketch Amount Modified:sketch amount increased