Wikipedia
Pseudo-photograph
A pseudo-photograph is "an image, whether made by computer-graphics or otherwise howsoever, which appears to be a photograph".
Although the term pseudo-photograph can be applied regardless of what it depicts, in law its meaning is especially relevant regarding child pornography.
In the UK, the Criminal Justice and Public Order Act 1994 amended the Protection of Children Act 1978 so as to define the concept of an "indecent pseudo-photograph of a child".