[Digikam-users] Dark Images for 16-bit raw and reconstructed highlights

[Gilles Caulier]

2009/5/26 Paul Waldo <paul at waldoware.com>:
> Hi Gilles,
>
> Yes, I can reproduce using dcraw, but the effects are not as bad.  I start with a raw from my Digital Rebel.  It has a full histogram; showfoto shows values from 0 to 64k if I do no highlight restoration.  I then used "dcraw -c -H n photo.crw | pnmtopng > photo_Hn.png" for n in 0..3.
>
> The H0 and H2 PNG show full-featured histograms from 0-255.  The H1 and H3 histograms, OTOH, show degradation.  The images are somewhat dark and the fullness of the histogram runs in the approximate range 0-230.  There are a couple little spikes after that, but essentially nothing.
>
> I guess this means this is a dcraw problem?

Yes, indeep i think.

I recommend to ask to dave cofin directly. All future fixes will be
reported later in libraw by Alex...

Gilles

>
> Paul
> ----- "Gilles Caulier" <caulier.gilles at gmail.com> wrote:
>
>> For me sometime, yes, sometime no, this depand of the picture
>> content.
>> Sound like improvment in libraw need to be done.
>>
>> Question : with your picture, can you reproduce the dysfunction with
>> dcraw command line tool ?
>>
>> Gilles Caulier
>>
>> 2009/5/26 Paul Waldo <paul at waldoware.com>:
>> > Can anyone else confirm that converting a raw with Unclip and/or
>> Rebuild Highlights produce a dark image with much shadow detail thrown
>> away?  I plan on filing a bug and want to make sure this is not just
>> my issue.  Thanks in advance!
>> >
>> > Paul
>> > ----- "Paul Waldo" <paul at waldoware.com> wrote:
>> >
>> >> Hi David,
>> >>
>> >> Thanks for having a look.  I find that "Solid White" and "Blend"
>> >> produce good results.  I get the dark image in "Unclip" and
>> "Rebuild"
>> >> mode.  Do you get the same results?
>> >>
>> >> Paul
>> >> ----- "davidvincentjones" <davidvj at verizon.net> wrote:
>> >>
>> >> > Taking your raw data ... I applied my usual 'blend' plus 'auto
>> >> > brightness'
>> >> > and found the image anything but dark.
>> >> >
>> >> > My reading of the image indicated slightly blown highlights but
>> a
>> >> good
>> >> > black
>> >> > range. I do not by the way think that my process lost the
>> highlight
>> >> > detail.
>> >> >
>> >> > Without using the 'auto brightness', and simply manually opening
>> up
>> >> > the data
>> >> > provides a very similar result.
>> >> >
>> >> > Are you perhaps using an icc that is totally incompatible?
>> >> >
>> >> > David
>> >> >
>> >> >
>> >> > Bugzilla from paul at waldoware.com wrote:
>> >> > >
>> >> > > Hi Mikolaj,
>> >> > >
>> >> > > Sorry it took solong to respond, but I had hosting issues...
>> >> > > The original raw file can be found here:
>> >> > > http://www.waldoware.com/photo2009-02-26_18-52-30-000034.crw
>> >> > >
>> >> > > I did a conversion using the defaults plus setting Highlights
>> to
>> >> > Rebuild
>> >> > > which is viewable here:
>> >> > >
>> >> >
>> >>
>> http://www.waldoware.com/photo2009-02-26_18-52-30-000034_highlights_rebuild.png
>> >> > >
>> >> > > BTW, only two out of the four Highlights options cause this
>> >> > truncation of
>> >> > > pixels.  Any ideas you have would be greatly appreciated!
>> >> > >
>> >> > > Paul
>> >> > >
>> >> > > ----- "Mikolaj Machowski" <mikmach at wp.pl> wrote:
>> >> > >
>> >> > >> On Tuesday 12 May 2009 15:20:25 Paul Waldo wrote:
>> >> > >> > Has anyone in the Digikam community had good results with
>> >> > Highlight
>> >> > >> > Rebuild?  I just can't get it to work without destroying my
>> >> > image
>> >> > >> :-(
>> >> > >> >
>> >> > >> > Paul
>> >> > >>
>> >> > >> I used HR successfully in the past, didn't use recently being
>> >> more
>> >> > >> careful
>> >> > >> when shooting. Could you post somewhere your RAW for testing?
>> >> > >>
>> >> > >> m.
>> >> > >> _______________________________________________
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>> >> > >
>> >> > >
>> >> >
>> >> > --
>> >> > View this message in context:
>> >> >
>> >>
>> http://www.nabble.com/Dark-Images-for-16-bit-raw-and-reconstructed-highlights-tp23414351p23556239.html
>> >> > Sent from the digikam-users mailing list archive at Nabble.com.
>> >> >
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