“It refers to the fact that Photoshop is used to make a new image from several others. He did on canvass what PS does on the computer”
Yeah, and that’s a stupid comparison, since unless they work in collage, painters actually create their own images on any particular canvas, rather than mixing seperate images together. Also, basically every artist who ever lived mixed on one canvas images he had pulled from different sources.
It is most certainly NOT the same as what photoshop does.