[argyllcms] Re: Camera calibration: LUT only as good as matrix?
- From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 3 Jul 2013 06:28:37 -0700
On Jul 3, 2013, at 1:08 AM, Torsten Bronger <bronger@xxxxxxxxxxxxxxxxxxxxx>
wrote:
> 1. Convert to TIFF:
>
> dcraw -M -o 0 -4 -T -A 2186 2678 51 118 -b 1.03 DSC02310.ARW
>
> The "-b 1.03" sets the brightness so that the GS0 patch has the
> desired value of approx 90.45. I don't know whether this is
> necessary. The -A parameter uses the patch GS4 for white
> balancing because it is supposed to be unsaturated according to
> the reference file.
Rather than use -b to normalize exposure, I've had much better luck developing
to a UNIWB gamma 1.0 TIFF, building a profile from that, doing a reverse lookup
of D50 white, doing a bit of math on the results, and using those values as the
channel multipliers. The result is a TIFF that has perfectly normalized white
balance and exposure both.
For details, see here:
http://trumpetpower.com/photos/Exposure
Note that I do the final development in that document not with dcraw but with
Raw Photo Processor. The math for deriving the white balance channel
multipliers is different between the two, and you'll be on your own to figure
out what that is.
Cheers,
b&
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