A digital matte painter was a matte painter who composited his or her mattes primarily in a computer. Their work could contain elements created in the real world, but ultimately all elements were processed digitally. As such, the credit was one that didn't appear before the advent of BBC Wales DWU productions. The credit tended to appear with greater frequency on programming during the first Russell T Davies era.
The Confidential episode Aliens: the Good, the Bad and the Ugly contained a segment about the discipline.