Czornyj brought up an interesting subject, Additivity Failure, which occurs for various reasons but is poorly quantified as it it exceedingly complex, non-linear, and worse, varies a great deal from one person to the next.
As a consequence of this unpleasantness, it's largely ignored and it would seem for practical purposes, ignoring it works sufficiently well and life goes on.
I'd like to examine this more closely and one thing that would facilitate this is being able to specify X,Y,Z values directly in Photoshop where RGB values would normally be entered.
One approach is to use an ICC matrix profile that converts from ICC working space to XYZ. Since the working space is also XYZ this should be the zenith of simplicity but I haven't run across a profile that does this.
There are a few issues.
- XYZ are absolutes that are linearly scaled to an arbitrary luminance.
- The actual XYZ values on a monitor are color adapted to the monitor profile's white point. The working space XYZ values are adapted to D50
Since I normally, especially in repro mode, work with the monitor set at D50 and 100 nits neither of these issues is a problem. For others there would need to be some of additional work. Possibly a set of profiles at different nit and monitor CCTs levels.
So, ideally, I would like to create color patches, or use standard patch sets like X-Rite's Colorchecker. Then place my cursor over the patch in PS, read the X,Y, and Z values, and then be able to do the same with an I1 monitor patch reader which directly reads these.
This would make exploring additivity failure in areas where I suspect it may be occurring much simpler.
Has someone run across anything like this: