I dont know if this has been posted before...open image in gimp, select filter-edge detect- edge, then OK in the preview box. Next select Image-Mode-Grayscale. save as (windows BMP seems to work best for me) I had to export the image to another graphics program to invert the colors,and clean up using bucket fill with the background color. Im sure gimp 2 can do it somehow. I wish that I had figured this out before I cleaned and recolored maly's albatros ofreg III by "hand". Joe PS. I was unable to upload a screen capture to show the process.