[Digikam-users] [SPF:fail] Re: Dark 16 bit RAW decoding

[Gerhard Kulzer]

Am Friday 25 January 2008 schrieb Paul Waldo:
> Thanks for the reply, Gerhard.
>
> OK, this make a bit more sense now as to *why* UFRaw is working for me. 
> Any thoughts on why my profile, generated in lprof, causes the conversion
> to be very dark, almost black?
>
> In case it helps, here is the output from lprof:
>
> I have chosen CIE XYZ as PCS
> Unknown white point (X:1e-314, Y:7e-312, Z:7e-312)
> Primaries (x-y): [Red: 0.625415, 0.277302] [Green: 0, 1] [Blue: 0.0833993,
> 0] Estimated gamma: [Red: 1.19788] [Green: 1.22472] [Blue: 1.24135]
> Loading sheets...
> Reference sheet: /home/paul/.lprof/target_refs/R060101.txt
> Measurement sheet: /home/paul/.lprof/temp/meaurement.cgt
> Gamut hull: 195 inside, 0 outside, 57 on boundaries
> Fitting error (delta E CIELAB): mean=1.97997, RMS=3.01769, 95%%=6.1929,
> median=1.09214, MAD=0.666138
> Fitting error (delta E CIE94): mean=1.10034, RMS=1.5087, 95%%=3.06707,
> median=0.777355, MAD=0.432199
> Performing 2-fold cross validation ...
> 2-fold CV: estimated RMS dE=4.04654, dE94=2.04384
> 2-fold adj. CV: estimated RMS dE=3.70133, dE94=1.86485
>
> Here are my profile parameters:
>
> Resolution (CLUT points):  33
> Profile verbosity: Store anything
> Regression:
>     Smoothness: 0.500
>     Deviation: 1.00e-05
> Linear Bradford
>
I'm not profile savvy enough to tell what's wrong with it. You can send me the 
profile to my address, it's not big. Or if you have icc-examin installed you 
can actually see the tone curves in a profile, if they're straight then 
there's no correction done.


Gerhard

> On Friday 25 January 2008 12:03:20 pm Gerhard Kulzer wrote:
> > Am Friday 25 January 2008 schrieb Paul Waldo:
> > > I stumbled across a discussion of dark RAW conversions in the FAQ.
> > > Apparently Digikam cannot use the manufacturer-supplied camera profile,
> > > yet UFRaw can. This puzzles me, since they both are just front ends to
> > > dcraw...
>
> [snip]
>
> > As I understand it, Canon profiles that come with the camera lack tone
> > mapping and gamma correction parameters. digiKam does not touch these
> > properties during raw conversion, but Ufraw does. They have a whole lot
> > of code to supplement dcraw in the conversion process. One day dcraw will
> > hopefully do it as it does it already for 8 bit, or we'll integrate the
> > ufraw code.
> >
> > On the other hand Bibblepro and selfmade lprof profiles work well with
> > digiKam in my experience since they have tone mapping included, images
> > come out normally bright.
> >
> > Gerhard



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