description
This command produces four colour separations for black, cyan, magenta, and yellow printing passes. The created files are local files with the same file name
The colour removal algorithm is to remove ALL the underlying black for each pixel in the red, green, and blue images and place that into a black separation. Corresponding changes are made to the cyan, magenta, and yellow separations.
[Note that in colour images produced synthetically or scanned in with filters, the result is red, green, and blue separations. Displaying that image on a CRT monitor uses additive colours, the red, green, and blue phosphors that emit light, so that max r,g,b adds together to display white. Printing that image on a piece of paper uses subtractive colours, the cyan, magenta, and yellow inks or toners that reflect light, so that max c,m,y subtracts together to reflect black. In effect, you can map r,g,b files to c,m,y files by renaming red—cyan, green—magenta, blue—yellow, and inverting the pixel values max—min and min—max.]
examples
% list -l [Indigo]<AIS>Baboon-*.AIS
Baboon-blue.ais!1 264192 30-Mar-78 23:58:16 PST
Baboon-green.ais!1 264192 30-Mar-78 23:48:59 PST
Baboon-red.ais!1 264192 30-Mar-78 23:36:54 PST
% FourColorSeparation [Indigo]<AIS>Baboon
Starting color separations. . . Done
% list -l Baboon*.ais
Baboon-black.AIS!1 264192 19-Jul-84 11:26:59 PDT
Baboon-cyan.AIS!1 264192 19-Jul-84 11:27:01 PDT
Baboon-magenta.AIS!1 264192 19-Jul-84 11:27:02 PDT
Baboon-yellow.AIS!1 264192 19-Jul-84 11:27:04 PDT
%
warnings
FourColorSeparation assumes that the red, green, and blue separations have -red.AIS, -green.AIS, -blue.AIS in their filenames. Using -grn or -blu will not work.