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any tricks for making black look really black

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any tricks for making black look really black Gez 29 Nov 19:47
  any tricks for making black look really black Gez 29 Nov 20:09
  any tricks for making black look really black Kevin Cozens 29 Nov 21:42
Gez
2015-11-29 19:47:32 UTC (almost 9 years ago)

any tricks for making black look really black

Kevin Cozens wrote:

When it comes to printing, black ink by itself won't give you a real dark black. The blackest-black you can get when printing in CMYK is C-75 M-68 Y-67 K-90 (from a formula on a web page). These percentages are different than I remembered. The main idea is that you need more than just black ink.

That's not correct.
The amount of black generation is controlled by the target CMYK profile, and you just can't create something that is blacker than your RGB black when working in RGB.
GIMP is an RGB editor, it can't produce CMYK separations unless you use a plugin, so the CMYK value in the picker is just a guide of how your colors are going to be separated when your RGB image is converted to a specific CMYK space.
You can't force values.

Those CMYK values you provided could be good for a certain CMYK space (which as a 300% total area coverage) but could be unsuitable for other colorspaces.

At the end it doesn't even matter, as you're absolutely unable to control how the profile will separate your RGB into CMYK unless you're using a tool that lets you control that.

In kwisj's case, I'd try to figure out why the printer is producing a weak black separation (maybe pulling a pure black from the separation, without any CMY beneath).
That's unlikely that is caused by GIMP or the file produced in GIMP, it would be the same producing an sRGB image from any other program.

Gez.

Gez
2015-11-29 20:09:46 UTC (almost 9 years ago)

any tricks for making black look really black

El dom, 29-11-2015 a las 16:47 -0300, Gez escribió:

 
In kwisj's case, I'd try to figure out why the printer is producing a weak black separation (maybe pulling a pure black from the separation,
without any CMY beneath).
That's unlikely that is caused by GIMP or the file produced in GIMP, it
would be the same producing an sRGB image from any other program.

Aaaand, replying to myself. If that's what I suspect (the printer/RIP producing pure K plate from the achromatic values), maybe there is a way to prevent it:

Try to add some color. Instead of pure black, use RGB 1,1,5.

Sometime RIPs, Printer drivers and preflight softwares have specific rules, as converting pure black to K-only black. By making it very dark gray and adding some tint to it, you cheat the RIP so it doesn't do that.

That should work giving you a nice, deep black. Try it and let us know how it went.

Gez.

Kevin Cozens
2015-11-29 21:42:14 UTC (almost 9 years ago)

any tricks for making black look really black

On 15-11-29 02:47 PM, Gez wrote:

The amount of black generation is controlled by the target CMYK profile, and you just can't create something that is blacker than your RGB black when working in RGB.

I wasn't commenting on what you would have to, or might need to do, in GIMP to get a deep black colour on a printed page.

Cheers!

Kevin.

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