Re: Feedback on success, creating a camera profile
Re: Feedback on success, creating a camera profile
- Subject: Re: Feedback on success, creating a camera profile
- From: Ben Goren <email@hidden>
- Date: Sat, 04 May 2013 09:31:30 -0700
On May 4, 2013, at 7:33 AM, MARK SEGAL <email@hidden> wrote:
> We have differing ideas about what constitutes explanation and justification. I'll leave it at that. The Adobe folks would be better positioned than me to address these contentions scientifically, if they chose to.
I'm not aware that there's anything even vaguely controversial about what I wrote. Read the DNG specification, and it's overwhelmingly clear that it's meant as a general-purpose tool.
Indeed, right at the top of chapter 6 on mapping camera space to XYZ, they discuss the reasoning behind supporting two different illuminants and the recommended strategy for extrapolating to other illuminants based on the user-selected color temperature. "Extrapolation" is what you want for this type of general-purpose tool, but -- obviously! -- it's not going to get you precise results.
And this sort of fuzzy logic pervades the spec. I kid you not, the first step in ``Translating Camera Neutral Coordinates to White Balance xy Coordinates'' is, ``Guess an xy value.'' They then describe an iterative process that will, indeed, provide not-bad results in a generic tool.
But if you actually want to perfectly normalize white balance and exposure, the way to do it is to shoot a chart, dump the raw data to a linear 1.0 gamma UNIWB TIFF, build a matrix profile, do a reverse lookup of D50 white, and use the resulting RGB values to derive linear channel multipliers for subsequent raw development. There's no guessing and the results are perfect within the error bars of your equipment.
It should be obvious why Adobe wouldn't take such an approach for their tools, and equally obvious why, as a result, their tools aren't capable of delivering the same results as different tools actually intended for the job.
Really, I have no idea why you're getting so upset over this. It's hardly different from cautioning somebody against trying to pull a boat in a trailer with a sports car. Sure, you can strap a canoe to the roof and you can probably jerry-rig something for a fishing boat, but that's not what the car is designed for and you'll get *much* better results using something that *is* designed for the task.
Cheers,
b&
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