censorship aside - there's a long history of this starting with the constructivists (specifically Rodchenko), bauhaus photographers and photomontage artists using both re-appropriated imagery and their own work. Some did it for purely 'artistic' purposes, some to give an entirely different socio-political meaning to the base image.
The examples you have are cut-outs against a background that shows through the photo, rather than something on the image surface obstructing the image.