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

[Paul Waldo]

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?

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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