Thank you for your comment In fact it is not exact, I began to paint on a photo of my bathroom (it's true ) in order to have something in the "black in white". After, i overpaint on this. The purpose of this technique is for not starting paint on white leaf, but with a material of departure. Otherwise, all the rest it is painted in the hand
The master of this technique is "LEVENTEP" He has an interesting approach and I advise to all people to look at his works.