Photomontage
Photomontage is the process (and result) of making a composite photograph by cutting and joining a number of other photographs. The composite picture is sometimes photographed so that the final image is converted back into a seamless photographic print. Today, image-editing software, although not using film, produces similar results. This latter technique is referred to by professionals as "compositing", and in casual usage is often called "photoshopping".
'Group of Royal Family'
by and after John Jabez Edwin Mayall
early 1860s
NPG x132718
Prince Albert of Saxe-Coburg and Gotha, Queen Victoria and their children
after John Jabez Edwin Mayall
circa 1861
NPG Ax9571
'The Kings and Queens of England: From the Conquest to Queen Victoria'
by Henry Hering
1862
NPG Ax131392
David Ball; Angus McBean
by Angus McBean
1956
NPG x39318
Angus McBean
by Angus McBean
1960
NPG x39317
Duncan Grant
by Godfrey Argent
7 June 1968
NPG x88049
Identity
by Liz Rideal
1985
NPG D11008
Sir Richard Branson
by David Mach
1999
NPG 6494