A topic has come up in a separate thread about wanting to use a press profile as the working space profile in Photoshop. As a general rule we don’t typically recommend this. But I thought I’d throw this out there for a discussion on the pros and cons of doing this.
In the meantime I’ll hunt around and see if we wrote an article on this in our newsletters.
I believe that unless the profile is specifically designed as a working space it is unwise to use it.
I cannot recall why I have this belief but I think it was something to do with how arithmetic is done within the working space.
Again memory stretching; the working space in LightRoom (Melissa) is a modification of ProPhoto and the modification was done to improve editing within the working space.
As far as RGB editing/working spaces are concerned, using a device profile as an editing space is a bad idea. In my opinion. That’s because edit spaces are not just for encoding the color meaning of pixels, but need to have predictable color behavior when moving those pixels from one location of the color space to another. i.e Editing. An Ideal RGB editing space would have things like as R=G=B, from 0 to 255, always being neutral. And being reasonably perceptual uniform too.
Grey balance is easy to achieve on a mathematically defined edit space like Adobe RGB, but R=G=B being neutral, from 0 to 255, won’t happen on a real-world RGB devices. Editing an image in a real world device space risks introducing undesired/unpredictable color/tone shifts as you change the appearance of pixels with tools such as curves and levels.
Much the same thing for perceptual uniformity of editing color spaces. When editing, you want the same size move to a pixel to mean the same size change to the pixels appearance, regardless of where you are in the color-space. Again that’s easy with a synthetic edit space like Adobe RGB, but probably won’t happen in a real world RGB device space. Looking at gamut plots in ColorThink of RGB print spaces that I build, I sometimes see non-uniformites in the gamut surface in wire-frame view. And I’d hazard a guess that that those non-uniformities wont just be on the gamut surface either.
My understanding is that CMYK editing spaces also need this same good behavior. For moving pixels around inside them. But I am not aware of the specifics of how they do that for CMYK editing space. Maybe someone here can explain how they do that.
Using a real-world press ICC profile as a workingspace could be fraught with possible issues:
While a press profile might create great color when converting to the press, if you’re using the profile as a working space then you’re editing your file in press CMYK, the press’s ideosyncratic device space. Everything that was odd about the press the day it was sampled, is now odd about your editing space.
All that said, G7 (and G7+) has the means to calibrate a printing system so that tonality and gray balance are predictable and similar in appearance to other systems.
If G7-calibrated press measurements were averaged over multiple sheets (or even better, multiple runs from multiple presses) and then smoothed using Curve4/+ Blend tool or other measurement massaging software like ColorAnt, then it might create a decent working space.