[Hervé]

I have all my grey maps (bump, disp, masks etc.) set to sGray in PS..

[tom]

For product or package visualization we will often get many variations of artwork designs in CMYK Illustrator format, with of course "white" as the negative space.
When these are rasterized to RGB you end up with an uncalibrated "linear" image but that includes white as the "not printed area."

Being quite fluent in desktop publishing and color management, I can't say I understand your workflow in this conversion. It does not really matter in what color space you create the artwork and making a CMYK to RGB conversion doesn't mean you ended up with a linear image at all. What's the destination RGB profile you're using in Illustrator?

[dmeyer]

For product or package visualization we will often get many variations of artwork designs in CMYK Illustrator format, with of course "white" as the negative space.
When these are rasterized to RGB you end up with an uncalibrated "linear" image but that includes white as the "not printed area."

Being quite fluent in desktop publishing and color management, I can't say I understand your workflow in this conversion. It does not really matter in what color space you create the artwork and making a CMYK to RGB conversion doesn't mean you ended up with a linear image at all. What's the destination RGB profile you're using in Illustrator?

Ok - sorry for the confusion. Upon further inspection it appears that when testing with PNG export out of Illustrator that Photoshop was not picking up the profile for some reason, but is with PSD and TIFF.

I suppose the question is then should we be applying any gamma to this before feeding it to maxwell?

[tom]

No, because what you see on your monitor as "correct" has already 2.2 gamma baked into its pixels.

[RichG]

[/quote] Upon further inspection it appears that when testing with PNG export out of Illustrator that Photoshop was not picking up the profile for some reason, but is with PSD and TIFF.[/quote]

PNG doesn't preserve profiles.

[tom]

PNG doesn't preserve profiles.

PNG exported from Maxwell does. Maybe, Illustrator is not doing the same.

[RichG]

PNG doesn't preserve profiles.

PNG exported from Maxwell does. Maybe, Illustrator is not doing the same.

Really? I'd always thought that was just a given with PNG format. Something new every day!

[tom]

http://www.libpng.org/pub/png/spec/1.2/PNG-Chunks.html

P.S. Only RGB color spaces though... CMYK is not supported.