A layout setting that forces the background color to be omitted exactly where a foreground element sits. Instead of printing the top ink over the bottom ink, the press leaves a blank hole in the bottom layer. This prevents unwanted color mixing, such as yellow printing over cyan and turning green, but it requires precise registration to avoid white gaps at the edges.
Heard on the job
Make sure that white text is set to knockout, or the RIP will just ignore it against the black background.
Do not mix it up with
- Overprint: Knockout removes the background ink, while overprint prints the top ink directly over the background ink.