Would this document shed any light on this subject? Help me understand it.http://developer.apple.com/library/mac/#technotes/tn2035/_index.html
I've been reading up on that after concerns over unexpected behavior changes in my Epson driver interface and how it deals with tagged images out of CS3 Photoshop print dialog using "Printer Manages Color" with my Epson NX400 in Mac OS 10.6.8.
At first in Tiger the Colorsync radio button was selectable over Epson Color Controls in "Color Matching" menu by first selecting "Photoshop Manages Color" in Photoshop print dialog. Now they're both grayed out with Colorsync selected. It's vice versa when "Printer Manages Color" with Epson Color Controls selected and both grayed out.
In Tiger and throughout all the driver updates I always get pretty darn close color matching where at the beginning it required the color space data be in AdobeRGB and using AdobeRGB and 1.8 gamma selected in Epson's Color Management menu.
Upgraded to new computer with OS 10.6 and now it worked having the data converted to sRGB. If I didn't have the right conversion it would show up in print similar to assigning each color space to the wrong data with regards to hue/saturation.
Now after subsequent Epson printer driver updates from Apple with the final in OS 10.6.8, it doesn't matter what color space the data is written printed out of Photoshop. I can edit the image in any color space and the Epson print using "Printer Manages Color" and the AdobeRGB 1.8 gamma Epson setting will render it faithfully in the print.
That document above got me to wonder how and in what spooling format the data of the image in Photoshop is being handed off for Epson to print from where I still get the same color match even with all these on/off driver settings and color space data changes. How is Epson, Photoshop and the image data working between each other in translating the data so it provides this match without "Photoshop Manages Color"? It's like it's generating the data from the color managed display screen dump.
This is the quote from the above Apple developer doc that makes me wonder if Quartz, PDF and Colorsync is getting involved under the hood when using "Printer Manages Color"...
From "Color Model In Quartz" chapter:
PDF color space equivalence
Another simple but very important concept that Quartz inherited from PDF is color space equivalence. An implied rule is that color conversions are necessary only if the source color space is different from the destination. Quartz takes advantage of this simple rule to properly organize the flow of color data through multiple rendering stages:
How is the data being handled and in what format is it being spooled from Photoshop and handed off to the Epson driver to get such close and consistent color matching through all the driver setting/color space changes that don't happen in Safari and Preview where I don't get a color match no matter the Epson setting or color space?
It looks as if there's something going on under the hood I don't think even the Apple and Epson engineers understand.
Correction: I can now get color matching out of Preview using Epson Color Controls and the AdobeRGB/1.8 gamma setting with the image written in sRGB. And now it works with the image written in AdobeRGB.