This is an adjustable script
only one parameter to tweak.
Works best on images that have some light areas.
Script-FU > Sketch > Quick Sketch
; Installation: ; This script should be placed in the user or system-wide script folder. ; ; Windows Vista/7/8) ; C:\Program Files\GIMP 2\share\gimp\2.0\scripts ; or ; C:\Users\YOUR-NAME\.gimp-2.8\scripts ; ; Windows XP ; C:\Program Files\GIMP 2\share\gimp\2.0\scripts ; or ; C:\Documents and Settings\yourname\.gimp-2.8\scripts ; ; Linux ; /home/yourname/.gimp-2.8/scripts ; or ; Linux system-wide ; /usr/share/gimp/2.0/scripts
