In photoshop, I took my drawing ( [link] ) I transformed it into a layer, I duplicated it, then transformed the duplicated one (on top of the first) in "multiply" (it turns it black and transparent instead of black and white). I applied a brown color between the 2 layers, and at last, I put white on top of all layers just where I needed it.
Hum ... scuse me for my poor english I hope you understand what I say !
Oh, you're really kind to explain me the whole process Yes, I understand, so it was a matter of coloring, that's nice. If you understood my typo [bceuase=because], I surely understand your english, which is perfectly fine, actually need not to worry