Do you mean what it means or where the setting is?
The setting is in CMYK color settings when you choose custom. You select the GCR radio button and scroll black generation to maximum
GCR stands for Gray Component Replacement, and means that the higher the amount of GCR you use, the more the black plate is used (and the less the CMY is used) to render not only neutral tones, but also uses more black as "unwanted" color to provide "drawing" to imagery.
Okay, thanks John!
All that makes total sense, but I was wondering if there was a place I could set my OWN custom black. Turning on GCR to have black generation be "maximum" sets 0/0/0/100. Is there a way I could, for example, have the default black be my own (or my client’s own) custom setting, say, 20/20/20/80 ?
I realize these are silly numbers, I’m just using them as a hypothetical.
I imagine profiling software gives you some control over the CMYK build that results from 0R/0G/0B, but I don’t think Photoshop gives you that option.
Not that you can’t create fills of that build in CMYK mode, or do some selective color work in blacks…