Bug 137278 - 16-bit/channel workspace when working with RAW conversions
Summary: 16-bit/channel workspace when working with RAW conversions
Status: RESOLVED FIXED
Alias: None
Product: digikam
Classification: Applications
Component: Plugin-DImg-RAW (show other bugs)
Version: unspecified
Platform: Ubuntu Linux
: NOR wishlist
Target Milestone: ---
Assignee: Digikam Developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2006-11-13 11:48 UTC by Jakob Østergaard
Modified: 2018-07-05 13:34 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In: 6.0.0


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Description Jakob Østergaard 2006-11-13 11:48:24 UTC
Version:            (using KDE KDE 3.5.2)
Installed from:    Ubuntu Packages
OS:                Linux

As a hobby photographer I have the following workflow when I process digital images from my camera:
1) First I copy the RAW files from the CF card
2) Then I run a batch job to convert all RAW files to JPEG
3) Viewing the JPEGs allows me to delete the 90% of the images that are not "good"
4) Then, using ShowPhoto, I take the remaining RAW images, one by one, and adjust colour levels, cropping, noise reduction etc. etc.

However, in step 4, I am losing some of the image quality from the RAW file, because the way ShowPhoto works, it converts the RAW image (which has 10 or 12 bits/channel resolution) to an 8-bit/channel work-space. I then "stretch" colurs and noise-reduce on the 8-bit/channel workspace. The resulting image will have holes in the histogram, if I stretch the curves of the image.

If ShowPhoto used a 16-bit/channel workspace instead, only converting to 8-bit/channel when saving the resulting TIFF, then the resulting image histogram would be without holes (in all the common cases, except when the curves are stretched violently).

I hope the above explains the work process and the problem, and my suggestion for a significant improvement. If this feature request is misplaced (sorry I don't know ShowPhoto/DigiKam internals), please let me know.

So, to sum up, I propose the following change:

ShowPhoto currently does:
1) RAW -> 8-bit/channel conversion
2) Allows user to edit image
3) Saves 8-bit/channel image to resulting file

I propose instead:
1) RAW -> 16-bit/channel conversion
2) Allows user to edit 16-bit/channel image
3) Scales to 8-bit/channel during save to resulting file

If someone can point me in the right direction, I might even have time to see if I can make this change myself (no promises though). Thank you very much, for a very useful tool :)
Comment 1 caulier.gilles 2006-11-13 12:10:34 UTC
Jakob,

Witch digiKam/showfoto release you use ?

Gilles Caulier
Comment 2 Jakob Østergaard 2006-11-13 12:40:22 UTC
Gilles Caulier wrote:
> ------- Additional Comments From caulier.gilles kdemail net  2006-11-13 12:10 -------
> Jakob,
> 
> Witch digiKam/showfoto release you use ?
> 
> Gilles Caulier


It's the one from the LTS Ubuntu packages - if you need the version 
number I'll have to get back to you tonight when I'm home. My home 
machine is not online now.

/ jakob
Comment 3 caulier.gilles 2006-11-13 16:10:32 UTC
Yes, the version number please...

Gilles 
Comment 4 Jakob Østergaard 2006-11-15 23:16:58 UTC
showFoto 0.3.1 from KDE 3.5.2.
Comment 5 caulier.gilles 2006-11-16 08:44:58 UTC
ok. You use digiKam 0.8.2. it support only 8 bits/color/pixel depth. 

16 bits color depth pictures and Color management support have been added into digiKam 0.9.0 (RC under way, final release planed at Christmast).

I mark this file like dupplicate than #103176 (witch have been closed).

I recommend you to read the web project page and especially this one :

http://www.digikam.org/?q=about/features09x

For more informations, look the NEWS files about 0.9.0 release with the full list of changes/fix/improvements released since one year :

http://websvn.kde.org/trunk/extragear/graphics/digikam/NEWS?rev=603529&view=auto

Gilles Caulier

*** This bug has been marked as a duplicate of 103176 ***
Comment 6 Jakob Østergaard 2006-11-16 09:39:35 UTC
Thanks a lot for the reply - and sorry I didn't find the information 
myself (I was looking - but obviously not hard enough).

I will try out 0.9.0 as soon as possible - it looks like it's exactly 
what I need.

Cheers,
Comment 7 caulier.gilles 2018-07-05 13:34:56 UTC
Not reproducible with digiKam 6.0.0 pre-release and libraw 0.19.

Gilles Caulier