[Digikam-users] A digikam beginner story

[Matthias Weiß]

Hi all!


 This is a rather lengthy story about my first encounter with digikam and
RAW files. It might give insight into a beginners view of digikam (maybe
useful for GUI design, default settings) or otherwise a hopefully
entertaining read.


I bought a Panasonic Lumix LX3 last week and since then I'm exploring the
possibilities of a good digital camera. I'm a novice with regards to digital
photography, but I'm an experienced Linux user.


After getting familiar with the camera I wanted to know whether I could open
a RAW file under Linux and convert it into a png or jpeg. gwenview failed as
I was expecting it and I thought the same would happen with digikam.

Before I started digikam, I copied 8 RAW files into a new folder in my
"Local Collections" path. All 8 images are night shots. I started digikam,
selected the new collection folder - and surprise - all 8 photos where
there. Wow, that was far to easy, no googling for patches, no esoteric
options somewhere on the command-line or other time consuming crap, just one
click and I got it.

So I got bold and wanted to convert one RAW file to a png. Intuitively I
marked one RAW file, selected "Tools -> Convert Images", chose "Format: PNG"
and clicked "Start". The progress bar was at 100% far to quickly so I felt
uncomfortable immediately. And I was right, in the "Result" column there was
an ugly "Failed." staring at me. Brilliant. Such a promising start, and now
the troubles are starting ... . I retried several times but being an
experienced Linuxer I knew it wouldn't change the result, this is
"deterministic Linux" not "random result Windows".

So I had to find out why I got that "Failed." result. Clicking around I
didn't get any information why the conversion failed. So I restarted digikam
from the command-line and watched the console output in order to find a
hint. Nothing. After some more trying around I double clicked the "Failed."
result and got the error message. Ahh, there it is, very well hidden indeed.
And the friendly dialogue told me:

"convert: No decode delegate for this image format ..."

So I googled for this, found out that this is the convert command from
ImageMagick and read in some user forums about some file formats that are
not supported and one has to recompile the ImageMagick package with some
options and hope for the best. Ah, so mystic errors, nothing works,
compiling yourself and patching around after all. This is Linux how I know
it. But I compiled and fiddled in makefiles, source code too many times to
do it again.

But I wasn't willing to admit defeat yet and tried another path. Why not
open the RAW file in digikam with the editor and safe it as png? OK, so
let's go. One RAW file marked, click on "Edit" and here we go. The progress
bar was moving forward slowly, aha, so now it is really doing something. The
100% mark was reached and - oh my god - what a disaster. The image looked
hell. Completely different than the small preview in the album view the
image now looked completely over exposed by several EV's, street lights
clipping throughout, the night sky looked like it was dawn, incredible noise
over the whole picture, I was deflated. My conclusion was: In the album view
probably the embedded thumbnail jpegs from the camera where used, and what I
see in the editor is the "work" of dcraw. I could come up with only 2
explanations for this disaster:

- dcraw isn't really up to the task and that's the best what it's able to do

- the sensor data is really this crappy and the camera jpeg engine is doing
one hell of a miracle job to come up with some usable results.

Reading articles on dpreview.com and parts of the digikam docu about what
the camera and proprietary RAW converters are doing "behind the back" of the
user, the message that my shiny new cam is a cheating chunk of plastic sank
in more and more. I felt betraid. Ok, so I had to search

the web for some esoteric, magic options to dcraw so that after a major
overhaul the image would be acceptable. No more dreams of getting a better
image than the default jpeg camera output, no illusions about preserving the
true, unmangled image data.

I tried several command-line options of dcraw I found on the web recommended
for my LX3, in every case the resulting tiff file was digital waste. A black
and white image with just noise and some random lines.

So I decided that on my operating system of choice - Linux - it was too
early to do RAW development. Disappointed I moved to my other computer with
a clean Windows XP SP2 installation, all stupid consumer crap from Microsoft
de-installed, nearly all services disabled, something that resembles some
shadows of decent OS. I took the CD bundled with my cam and installed
SilkyPix. Or at least I tried. Because the installation routine stopped at
the last step telling me that "Installshield was interrupted" and it is now
terminating the installation without installing anything. Fantastic. Because
no further explanation was presented I searched for temporary folders where
SilkyPix was decompressing and preparing it's installation in the hope I'd
find some hint why the fracking installation died. Nothing. Again I fiddled
around for an hour or so and eventually gave up again. 2 defeats in 1 day.

I moved back to the 1st computer, which is a dual boot, starting my
completely messed up Windows 2000 installation. I stuffed in the SilkyPix CD
and - surprise - it installed uncomplainingly.

Also the RAW file development was doing fine, beautiful images as results.
But I could only convert to jpeg or tiff. No png. And I knew that some magic
rework to the crappy sensor data was going on in the background, out of my
control or insight, and I disliked this thought allot.

But at least I could use the RAW file capability of the cam, one reason I
chose the LX3 over some other compact cams without RAW file option.


 Next day I was taking photos again in RAW format, this time day shots.
Because during my tests of RAW file handling in digikam this program
impressed me allot, I wanted to explore it a bit more. Further I was
interested to see how the data of a day shot RAW file would look like. When
the night shot was already overexposed and clipping, what would happen with
photos having lots of brightness?

But this time I chose to use the "Import" functionality in digikam. After I
created a new album I right clicked on it but got no "Add Images" in the
context menu as I'm getting with the menubar in the Import menu.
Deliberately inconsistent? Don't know. I downloaded the new RAW's into my
new test album, selected the album, selected 1 image out of it and headed
for "Tools -> Convert Images". But suddenly this was greyed out. Huh?

Fine, so I started the editor, curiously waiting for the progress bar to
reach 100%, and there it was: just beautiful. Correct exposure, nice
colours, no clipping, practically no noise. I was puzzled.

Once again I thought about possible reasons and could think of only 2
explanations:

- The sensor of my LX3 has difficulties with long exposed night shots

- There is a difference in how dcraw/libraw handles the RAW decoding

I took the latter more comfortable explanation and once again went over the
possible RAW conversion settings. And suddenly it blinked into my eyes:
"Auto Brightness". I took the night shot again, untoggled this "Auto
Brightness" option, hit the "Update" button and a beautiful night shot
appeared. No noise, no clipping, correct brightness.


 In summary, choosing accidentally a dark image together with a default
option that was unusable for exactly this type of photos spoiled my first
encounter of RAW file treatment under Linux/digikam. Which is a pity because
I really got to like digikam, a deep bow to the developers.


 So now I only have to find out how to get rid of that damn barrel
distortion ...


 regards

matthias
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.kde.org/pipermail/digikam-users/attachments/20091010/9bd26591/attachment.html>