Hi Jose, No, L*a*b* is not the ACR internal working space. (*) ACR's primary internal representation uses the ProPhoto/RIMM/ROMM RGB primaries. Exposure and brightness are based on the traditional logarithmic base 2 formulation (i.e., in stops). So boosting Exposure to +1, for example, means doubling the linear scene-referred values (i.e., increasing exposure by 1 stop). The white balance math (color temperature and tint) simply associates user-chosen white points (e.g., tungsten) to corresponding camera whites, by means of a profile's color matrix or matrices. More details (for developers) can be found in public DNG SDK on the Adobe site. Cheers, Eric (*) ACR does use L*a*b* for some internal color difference estimates, e.g., for auto-calculated masks. On May 23, 2011, at 5:51 PM, José Ángel Bueno García wrote:
Hi Barry, Hi Tom:
The procedure at institution is avoid .tif or .jpg and shot raw from DSLR camera. Of course the raw is .dng.
"I always ask the question: "What is the intended use of the data after acquisition?" can be the site of the institution, inkjet print or offset, so the DNG raw serves with the software tools that most of us have access: DNG Converter, DNG Profile Editor, PS CS,...
Are you saying that GaMapICC isn't usefull? Or RoughProfiler. You can make conversions having the source of light for visualization in account.
For what I know, lights at exposure spaces are "something near" D50 (halogen tungsten), or the manufacturers try to get it. And what about the fast chromatic adaptation of human eyes?
I reproduce art and photographic artifacs with flash, not with an almost monochromatic light as anyone can see in a SPD graph, and because is the less spiky light source (flash) that I know.
In the other hand, is not L*a*b* the ACR working space?. L* for the exposure and brightness, a* for the color temperature and b* for the hue/shade (I think my translator don't works fine here).
For me the less usefull illuminant is D65 that is high latitudes daylight most of the time, far away from 4950ºK in subtropical environments.
Salud
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