New article on color management

Started Apr 26, 2013 | Discussions thread
Detail Man
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Re: Camera-->sRGB versus Camera-->ProPhoto-->sRGB
In reply to Iliah Borg, May 28, 2013

Iliah Borg wrote:

Detail Man wrote:

All raw converters ultimately have to take the demosaiced raw camera coordinates (RGB or GMCY) and map them to XYZ or Lab, though it may be only an intermediate step. This is especially true for raw converters that use ICC profiles, where either XYZ or Lab D50 is the working space. The final mapping from XYZ to any of the standard RGB spaces is just a linear transform plus an encoding curve. The lookup tables provide a mechanism for non-linear corrections (e.g., if you need to tweak deep saturated reds differently than less-saturated reds, something the earlier matrix-only profiles obviously could not do).

- Eric Chan, Reply #51 on: July 28, 2008, 08:31:26 PM

http://www.luminous-landscape.com/forum/index.php?topic=26524.msg211284#msg211284

Iliah Borg wrote:

All raw converters ultimately have to take the demosaiced raw camera coordinates (RGB or GMCY) and map them to XYZ or Lab

Thу above is incorrect.

(Perhaps) one exception being RAW Photo Processor (RPP) ?

The "have" part is totally wrong. Fantastically wrong.

Interesting. I wanted to attribute the statement to its author (Eric Chan). I wonder if any digital cameras exist that may take such approaches. You mentioned that in your understanding this might (at least in the case of the Olympus E-M5) be a typical in-camera processing scenario:

Iliah Borg wrote:

Yes. Essentially (simplifying and omitting any secrets of trade) what happens is:

Apply WB; run 1st stage NR and sharpening; perform demosaicking; convert from camera colour to XYZ; apply 2nd stage of sharpening on Y; convert to LCH; apply tone curve to L; apply saturation to C; apply "look" to H; apply 2nd stage of NR over L and C; smooth H; apply convert to output space (like sRGB or AdobeRGB).

http://www.dpreview.com/forums/post/42201474

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