[Openicc] Named color profiles

[Chris Murphy]

I am slightly confused about named color profiles also. I have seen one, because I made it myself with some software about 8 years ago. I have never seen one since. I've never seen one used, or implemented the use of one at any client location. When writing RWCM it was one of those things where we kinda had to punt on. There are few (if any at this point) tools that make them, and I think even fewer use them. It was a good idea that just somehow went nowhere.

NCP's device values are optional. The only thing required is either an XYZ or LAB value for the color. The point of device values is they can be "hand tuned" visually to get better results than just passing the XYZ/LAB values through an output device profile, for a particular device (condition) like a color laser printer.

Since the PCS is defined as D50, I don't see how you can have anything other than D50 based values. They'd have to be chromatically adapted for some other lighting condition in a CMM or elsewhere it seems.


Chris



On Apr 10, 2011, at 3:27 AM, Richard Hughes wrote:

> I'm slightly confused about named color profiles. I've been asked to
> support NCP in the gnome-color-manager viewer tool, but I'm a little
> unsure of the basics.
> 
> As I understand it, each named color in a profile has a title (with
> shared prefix and suffix) and two values, a PCS value and a device
> value. I'm struggling to work out what the device value should be, if
> the PCS is XYZ. Even if the PCS is Lab, surely for v4 profiles we
> assume D50, and we can trivially work out the LAB value from the XYZ
> value or vice versa. Basically I'm struggling to work out why you
> would ever want a NCP with a PCS of Lab.
> 
> So a few questions:
> 
> * If the profile is v4 and PCS is XYZ, what values do I put into the
> NC device? The same as the NC PCS?
> * Do PCS Lab named color profiles exist? Does anybody have any
> examples of NCPs of either PCS type?
> * Is is possible to have a v2 NC profile with D65? Is it sane?
> * What's the normal convention of displaying the
> %{prefix}%{title}%{suffix} to the user as text? Delimit by " " or by "
> - "
> 
> Thanks for any advice.
> 
> Richard.
> _______________________________________________
> openicc mailing list
> openicc at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/openicc