Re: [Gimp-print-devel] Calculating actual Ink amounts from CMYK pipeline

[Solomon P. <pi...@sh...>]

On Mon, Jul 01, 2024 at 03:00:49PM -0400, Walker Blackwell wrote:
> I can follow 60% of this . . .

When it comes to this stuff, I feel like the one-eyed king leading the 
blind.  :(
 
> If I were to force it to print the basic CMYK percentages (basically 
> nix all the GCR combo stuff and print 40% black if that is what the 
> pixel has for its K value no matter what)
> 
> I see that I can just say output[0] = k;
> 
> But I don’t follow the logic of ck * cg.

I _think_ what happens here is that it works out the common K between 
the channels, then uses a (non-linear) lookup table (and the color 
balance knobs) to figure the corresponding amount to reduce each channel 
by.

> Maybe ideally I’m simply saying for the color outputs that it’s 1 * 
> cg->color_balance. ?

That sounds logical, but I've never sufficiently immersed myself in 
gutenprint's core color channel stuff to truly understand it, and I'm 
embarassed to say I've probably forogotten 89.3% of what I managed to 
absorb the last time around.

 - Solomon
-- 
Solomon Peachy			      pizza at shaftnet dot org (email&xmpp)
                                      @pizza:shaftnet dot org   (matrix)
Dowling Park, FL                      speachy (libera.chat)