[Digikam-devel] [Bug 130996] New: Wish: More control over jpeg options
jwest at melaque.com
Mon Jul 17 21:04:44 BST 2006
------- You are receiving this mail because: -------
You are the assignee for the bug, or are watching the assignee.
Summary: Wish: More control over jpeg options
AssignedTo: digikam-devel kde org
ReportedBy: jwest melaque com
Version: 0.9.0-svn (using KDE 3.5.3, Debian Package 4:3.5.3-1 (testing/unstable))
Compiler: Target: i486-linux-gnu
OS: Linux (i686) release 2.6.15-1-686-smp
More control options for jpeg creation.
Example, the 'advanced' save option for gimp 2.2 allows control for Optimize,
Smoothing, Progressive, use restart markers, force baseline jpeg, Sub sampling,
DCT method, and editable comment field.
I am really interested in having easy control over Subsampling. This option was originally in jpeg to help further compress large files by averaging out similar colors, in able to reduce the jpeg file size. The default value for libjpeg is
2x2, 1x1, 1,1 . Digikam currently does not set this option, and therefore uses this default. Breifly, this default option throws away half of the color information, perhaps great for vidio compression, but not for todays high-quality color photography.
For those who might be impatient as I was, you can quickly add the following to graphics/digikam/libs/dimg/loaders/jpegloader.cpp around line #485, after the line: jpeg_set_defaults(&cinfo); to set the subsampling to not compress as much.
cinfo.comp_info.h_samp_factor = cinfo.comp_info.v_samp_factor = 1;
This will give much larger jpeg's as the color information is not as compressed.
thanks for considering.
More information about the Digikam-devel