Cross colouration is the presence of false colour in
an image. This only affects video that has been processed in composite
format rather than being processed in component format. For further details
on how this artefact comes about, see my Video
Connectors article. Areas of closely spaced lines in the image take
on false colours between the lines, typically a purple discolouration.
White shirts with fine dark stripes are particularly prone to showing this
artefact. Black and white movies that have been processed at some stage
in composite format are also prone to showing this artefact, as a purple
discolouration around fine lines.
Eric Clapton: Unplugged 2:06
Close up of Eric Clapton's collar - note the finely spaced black lines
on his shirt and collar and the resultant false colours on his collar in
the image.