[argyllcms] Re: RGB black is not clean
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 18 Oct 2021 15:47:41 +1100
0815xl@xxxxxx wrote:
Hi,
my cmyk profile has a neutral black in the aF rendering intent (7,5 -0,6
-0,3).
Unfortunately not the RGB profile, its black (aF) is deeper but not neutral
(4,6
3,8 -4,0).
Would more yellow fix the error? What can I do to fix it?
if you are using printcal to create the linearization, then take
a look at the maximum device target values you are using.
(Actually I can't remember if it' s the maximum or minimum values
you should try changing for a print RGB space. You might
have to experiment and find out.)
You can probably change them to adjust the black point hue
to some degree, but usually you will want to keep one
channel at 100% while reducing one or two of the others.
There is a tradeoff between the L* value and how neutral it will be.
I have now viewed black from cmyk and rgb profile in photoshop.
You mean the raw raster values sent to the printer ?
If I convert sRGB into my printer color space absolute colorimetric. I get 5
3 -4
(RGB) and 7 0 -2 (CMYK).
You can clearly see that cmyk is better/more neutral.
But not quite as dark.
With RGB there is still plenty of reserve, why it cannot reach 7 0 -2?
It depends on what the linearization is doing to your values, and
how you printer is converting from RGB to CMYK.
Cheers,
Graeme Gill.
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