Artistic Style in AKVIS Sketch
AKVIS Sketch offers 2 styles of photo to sketch conversion: Classic and Artistic (http://akvis.com/en/sketch/)
"Artistic style is designed to create expressive drawings that look like the handmade work of a real artist. In this style, it is easy to create both a quick sketch and a carefully drawn and shaded pencil drawing. The main advantage of this style is the ability to play with hatching and to vary the number of shadings and shadows to give natural tonal transitions."