Yet again, as I learn in Wikipedia, just how little did I know:

Décollage, in art, is the opposite of collage; instead of an image being built up of all or parts of existing images, it is created by cutting, tearing away or otherwise removing, pieces of an original image.[1] The French word “décollage” translates into English literally as “take-off” or “to become unglued” or “to become unstuck”. Examples of Décollage include etrécissements and cut-up technique. A similar technique is the lacerated poster, a poster in which one has been placed over another or others, and the top poster or posters have been ripped, revealing to a greater or lesser degree the poster or posters underneath.