image resizing - digikam CIMG is GREAT! and icc profile problem

[Elle Stone-3]

Hi all,

It has been a while since I've used digikam.  Recently I decided to take the leap from monitor to paper and actually have a print made from one of my digital images.  My digital image needs to be enlarged x4 (x2 in length and width).  So I've been testing various (windows and linux) programs for image resizing.  Amongst the "ordinary" image resizing programs, ImageMagick's default "Mitchell" seems to me to be quite better than those supplied by that "900 pound gorilla" of imaging programs.  However, I wanted to try CIMG and look there! - digikam 9.3 (installed per Debian Lenny) has a REALLY nice interface to CIMG!  The progress bar really helps, too - I still don't know if my command line attempt to use greycstoration actually was doing anything or not.  And look there again! digikam 9.4 beta 4 (installed from source today by yours truly) has the latest and greatest CIMG!  Too, too cool, and the results are stellar!  Yeah!!! digikam!!!  Yeah!!! CIMG!!!  

Now, if I could just figure out what all those CIMG options mean - I've just been using the defaults so far.  But that is a topic for another post and if/when I get some experience with or info about modifying the defaults, I'll post what I find.

In the meantime, I have a question about icc profiles.  I use argyll to calibrate my monitor.  I do most of my image processing using linear (gamma=1) prophoto as my workspace icc profile (though I've been thinking about switching to ***linear*** wide gamut).  I put my linear prophoto icc profile in /usr/share/color/icc.  But neither digikam, nor krita for that matter, seem to recognize that the linear prophoto profile is in the icc folder.  

When I open an image for resizing purposes in digikam, digikam correctly reports the image profile and offers to convert or assign wide gamut.  But I don't want to convert to a nonlinear space.  Image resizing is more accurate when done in a linear space (see http://www.4p8.com/eric.brasseur/gamma.html).  So I just tell digikam to "do nothing".  The CIMG image resizing works perfectly anyway.  However, digikam displays all my linear image files as very, very dark - it doesn't seem to be applying the icc transform or whatever it is, that tells how to properly interpret and display on the monitor the rgb numbers in the image file.  

I don't really mind the dark display because at this point I'm not using digikam for anything other than image resizing, and after resizing, the resized images display perfectly when opened by the "900-pound gorilla".  However, if digikam COULD properly display my images using the embedded icc profile (that digikam obviously detects when I open the image), then I would love to start using other editing features offered by digikam.  And I'd like to start using digikam to keep track of my edited images.  But that dark display is a bit of a downer.

Is there a solution?  Have I failed to read the manual sufficiently carefully?  Is there a configuration setting that I could modify to enable digikam to use my linear workspace profiles?  Would a linear wide gamut profile fare better than the linear prophoto profile?

Thanks in advance for any suggestions and again, digikam's CIMG interface is just great!

Elle

[Elle Stone-3]

elle stone wrote

I put my linear prophoto icc profile in /usr/share/color/icc.  But neither digikam, nor krita for that matter, seem to recognize that the linear prophoto profile is in the icc folder.  

Hmm, it seems that digikam keeps its icc profiles in /usr/share/apps/digikam/profiles?  But I just now put my custom icc/icm profiles in the digikam profiles directory and started digikam.  Digikam still doesn't acknowlege my profiles.  Is there any way at all to get digikam to use additional profiles beyond the default profiles?  

Elle

[Elle Stone-3]

Hmm, I think I have figured out part of the icc profile problem.  I just managed to get digikam to "recognize", that is, list, all my usual icc/icm profiles in the "configure workspace profile" drop-down box.  The trick was to copy them all over to a folder in my home folder and "chown" them to myself.  I am sure that digikam would be just as happy no matter where they are located, but I (rather than "root" - "root" owns the /usr/share/color/etc files and folders) have to be the owner of the files.  

Alas, having my profiles listed in the digikam configure workspace drop-down box still doesn't make digikam display my linear gamma images properly - they are too dark - clearly the "message" that these images have gamma=1 is not getting across to digikam.  Krita displays the same images just fine, so somewhere between digikam, me, and my linear gamma images, there is still an "issue."  

Any, any, any suggestions on how to convince digikam to properly display a "gamma=1" color profiled image would be greatly appreciated.

Elle