The scenario - have an inkjet printer which regularly runs out of black
ink, but still has plenty of colour ink. I would like to change black to
dark blue or whatever, so I can print eg. a concert ticket with a black
barcode, which will still scan fine at the venue entrance.
On SGI in Days of Olde, this would be " repcol ticket.rgb 0 0 0 0 0 20
10 " or similar, ie. replace all pixels within 10 units (out of 255) of
black with dark blue. Good old Paul Haeberli and his gfx tools.
Appreciate assistance in doing this in Gimp - 2.6.7 on Mac with Snow Leopard
(10.6). Or indeed a command line tool of any kind, I need this little trick
quite a bit.
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