[Digikam-users] Dark 16 bit RAW decoding

[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...

My manufacturer-supplied camera profile works great in UFRaw, with gamma set 
to 0.45.  When I use the same profile with Digikam, I get a dark image.

So, I tried to take the FAQ's advice.  I created a profile by photographing an 
IT8 target and using lprof to create a profile.  When I use this new profile 
for Digikam RAW conversion, I get an image that is even darker than when I 
used the manufacturer-supplied camera profile! :-O

I'm sure that someone out there has gotten 16-bit decoding of Canon raw images 
to work well.  Any hints?  Thanks in advance!

Paul

On Wednesday 16 January 2008 10:30:47 am Paul Waldo wrote:
> Thanks for the reply, Jakob.  Comments below...
>
> Jakob Østergaard Hegelund wrote:
> > On Wednesday 16 January 2008, Paul Waldo wrote:
> >> Hi all,
> >>
> >> When I try to edit a RAW image, it is very dark.  Yes, I did RTFM; I
> >> have color management enabled :-)
> >>
> >> I'm running digikam 0.9.2-final on KDE 3.5.8
> >> Here are my digikam settings:
> >>
> >> Color Management
> >> ------------------------------
> >> Enable Color Management: on
> >> Launch Color Management plugin with RAW files: on
> >> Use color managed view: on
> >> Color profiles selected for Monitor, Workspace (Adobe RGB), Input,
> >> Soft Proof
> >> Black point compensation: off
> >> Rendering Intent: perceptual
> >
> > My guess would be that you're using the wrong profile.
> >
> > I had a *lot* of problems with this, but with the right profile for the
> > camera (and none for the monitor as it's sort-of close to sRGB which I
> > also use as workspace), everything works.
>
> I'm using the same profiles that work great in UFRaw.  That got me to
> thinking about the differences.  When I convert using my profile in
> UFRaw, I set the gamma to 0.45 and linearity to 0.02.  I see no way to
> do this in Digikam...
>
> >> RAW Decoding
> >> --------------------------
> >> 16 bit color depth: on
> >> Interpolate RGB as four colors: off
> >> Use camera white balance: on
> >> Automatic color balance: on
> >>
> >> Thanks for any insights!
> >>
> >>
> >> Paul
> >>
> >> PS
> >> Is there any way to select a specific color balance when converting
> >> RAW?  Camera WB works most of the time, but sometimes I need a manual
> >> WB, such as when photographing with a grey card.
> >
> > The RAW converter uses the cammera supplied WB, which means, if you set
> > the custom WB on the camera when you use grey card (select the grey
> > card image for custom WB before shooting the real photos), the correct
> > WB will be applied automatically during conversion.
> >
> > At least this is how it works in 0.9.2 with my EOS 350D.
> >
> > For actual WB adjustments later on, use the WB adjust tool in the
> > editor.
>
> Ah, OK.  I had not seen that before.  FWIW, I tried setting gamma here,
> but it had no effect.  The only thing I could do was the the EV
> Compensation way up (3 EV).  In order to do a manual WB with the picker,
> I had to guess where to click because the image was so dark!