Re: [Gimp-user] Pure black n white with smooth curves

[Liam R E Quin <liam holoweb net>]

On Sun, 2018-04-29 at 07:22 -0500, Frank Turk wrote:
>   If there was a way to extract the "K" layer in a "CMYK"
> image,
> it might be easier to grab just the black. 

You can use the separate+ plugin to do that, although what people think
of as "pure black" for printing is not actually 0 in CMYK value -
designers more often specify a rich black, e.g. Adobe Rich Black, whic
(depending on the final print medium) might be 0.75, 0.68, 0.67, 0.90
CMYK respectively.

There's also undercolour removal and overprinting.

For the origial question, i'd probably desaturate and use curves with a
very steep slope, the endpoints (bottom and top) close to the middle of
the image.

I used desaturate, then value propagate (more black, 0.2 or so) to make
the lines more robust, then curves, to make
http://www.holoweb.net/~liam/download/ankhslave-gimp-original.png
The curves looked like this:
http://www.holoweb.net/~liam/download/ankhslave-curves.png

liam (ankh)


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