When it uses photographs, this method of sticking various images on one surface is called "photomontage"
The Abstract Expressionists of the 1940's and '50's also used this 
method, .... figure/ground - The relationship of the picture surface (ground) to the 
images on... [DOC] [TLE] Art Terms and Definitions [PAR] art education lesson terms and definitions for use with Arttango.