[Digikam-devel] raw problems

[Arnd Baecker]

Hi,

I was about to test the patch
http://bugs.kde.org/show_bug.cgi?id=142055
but before I wanted to look at that current status
to see the difference.

There are various problems in the following situation:
Take the same image in the two versions RAW and JPG
(as they come out of the camera, Canon EOS 350D for this example),
with no color management enabled.

Tests A:
"RAW Files Decoding Settings"
- 16 bits color depth
- interpolate RGB as four colors
+ White balance: "Use camera white balance"
+ Automatic color balance
+ Highlights: Solid white
+ Brightness: 1.0
+ Interpolation: Bilinear
- noise reduction
- enable chromatic aberrations


Tests A - results for the comparison of RAW vs. JPG
---------------------------------------------------

- the thumbnails look very similar
  (the histogram of a screenshot for each thumb
   show only a small variation)

- The histogramms for RAW and JPG differ considerably
  (for the raw one all its weight is near small values).

- BUG:
  first going to the CR2 is fine, histogram is computed
  (takes long!) and shown.
  Then go to JPG - ok.
  Then back to the CR2 - the "Histogram" TAB says
  "Loading image" and this never finishes.
  (will file a separate BKO for this)

- Then, in preview mode (Setting: extract embedded preview)
  going back and forth between JPG and RAW
  one sees that RAW and JPG differ in width slightly
  (Colors etc. are essentially identical)
- With setting:  "Embedded preview load full image size"
  the colors are different
  (the raw one appears much more green).

- Loading the images into the editor,
  they look pretty much like
  those from the preview (when "Embedded preview load full image size"
  is activated), i.e. the raw one appears much more green.


Tests B - results
-----------------

change in the setting:
+ 16 bits color depth

Everything as in A), but:
In image editor: in 16 Bit: almost dark image
(which corresponds to the histogramm seen before ;-)

With patch
----------

Applying
http://casta.nerim.net/digiKam/digikam-kde3-WB-ufraw-multiplier.patch
(which did not change anything?)
and
wget http://casta.nerim.net/digiKam/libkdcraw-kde3-dcraw-WB.patch
wget http://casta.nerim.net/digiKam/digikam-kde3-dcraw-WB.patch
wget http://casta.nerim.net/digiKam/kipi-plugins-kde3-dcraw-WB.patch

Hmm, I don't see a different behaviour compared to A).
So presumably I am looking for an effect at the wrong place
(Just showing off that I haven't understood how to work with
raw under digikam ...;-)

Best, Arnd