.TH BLIND-CHROMA-KEY 1 blind
.SH NAME
blind-chroma-key - Replace a colour range with transparency
.SH SYNOPSIS
.B blind-chroma-key
.I key-stream
.SH DESCRIPTION
.B blind-chroma-key
reads a video from stdin and colours from
.IR key-stream .
Each frame in
.I key-stream
should contain exactly two pixels. The colour of
the first pixel, and all colours with a distance
from that colour upto the same distance the colour
of the second pixel has to that colour, will be
turned into transparency in the video from stdin,
and the resulting video will be printed to stdout.
.P
If the two colours in a frame from
.I key-stream
have the same alpha value, all matching colours
will be turned into full transparency. Otherwise,
the colours matching the first colour will be
given the transparency specified with the first
colour, all other matching colours will have
a transparency between to two specified alpha
values. However, if alpha value of the second
colour is less than the alpha value of the first
colour, twos alpha values are inverted.
.SH SEE ALSO
.BR blind (7),
.BR blind-from-text (1),
.BR blind-colour-ciexyz (1),
.BR blind-colour-srgb (1),
.BR blind-dual-key (1),
.BR blind-primary-key (1)
.SH AUTHORS
Mattias Andrée
.RI < maandree@kth.se >