[Openicc] Open Source compatible AdobeRGB profile

[Hal V. Engel]

On Tuesday 04 July 2006 16:22, Hubert Figuiere wrote:
> This is a very important matter as support AdobeRGB colorspace is a
> requirements for digital photography applications, including but not
> limited to DNG support. I shall remind that most cameras offer to save
> images in the AdobeRGB color space, and that the DNG specification
> mandates that AdobeRGB color space be supported as it is one of the
> possible color space.

Well it is correct that some cameras create images that are supposed to be in 
the AdobeRGB color space it may not be so in the real world.  All devices 
have sample to sample variation and each device really has its own color 
space even if the device vendor says otherwise.  Therefore a camera that 
saves an image in a specific generic color space such as sRGB or AdobeRGB is 
in fact just taking a best guess at what the devices actual color space is 
and then converting the image into some default color space such as sRGB or 
AdobeRGB.

Even if your camera "produces" AdobeRGB or sRGB images you still need to 
periodically create custom profiles in order to have truly correct 
characterization of the device.   This process is fairly simple and there are 
at least two open source options for software to do this.  All that you need 
in addition to the software is an IT8.7/2 target and a little time to 
photograph or scan the target and create the profile(s).

I should add that my experience with profiling RAW processed images for DSLR 
cameras indicates that the actual color space of this class of devices is 
much larger than the AdobeRGB color space.  So I have significant 
reservations about the utility of small (sRGB) or medium (AdobeRGB) size 
color spaces for high end digital photography.

I looked over the DNG specification and I didn't find any reference to 
AdobeRGB or any other specific color space other than the PCS which is XYZ.  
I am not sure why you think that ".. the DNG specification mandates that 
AdobeRGB color space .."  since "AdobeRGB" is not to be found in the 
specification.  I have to admit that I don't know much about this 
specification and perhaps there is some other document that covers this.

Hal