I wrote some software based on some academic papers to painterly render (Stroke Based Rendering) a photograph. The software takes a photo and turns it into a painting (turn photo to painting). Here, the software simulates brush marks but you can also simulate impasto or digital painting. Check http://3dstereophoto.blogspot.com/p/painting-software.html for free image-based non photorealistic rendering software for windows 64 bit.