[Digikam-users] Some color management questions

[Paul Waldo]

Hi Rainer,

Have you calibrated your monitor?  This is the process of adjusting your monitor's controls so that your color display is standard.  It makes sure that you get the highest dynamic range possible and that there are no color casts.

KDE has a rudimentary calibration tools in Display|Gamma.  I'm not wild about it, but it may work for you.  I use gammaPage, available at http://www.pcbypaul.com/software/GAMMApage.html.  It works similarly to Abobe Gamma, but also allows you to see if you have an overall color cast.  Hope that helps!

Paul
----- "Rainer Krienke" <krienke at uni-koblenz.de> wrote:

> Hello,
> 
> i run digikam 0.10 on my openSuSE 11.1 box. All my photos are in sRGB
> 
> colorspace. JPG files I convert from my cameras NEF files (using
> bibble) are 
> also in sRGB. In digikam colormanagement is disabled. So far so good.
> Up to 
> now I never had any color problems.
> 
> Today a friend send me some JPG photos. I know he also shoots in RAW
> (Nikon 
> D300) and then converts these files into either tiff or JPG. We spent
> a 
> holiday together and now exchanged some photos, he sent me JPG files.
> He is 
> working with windows, I guess to remember he is using Nikon Capture
> and Adobe 
> Photoshop to process his photos.
> 
> When I saw his photos and compared them to mine the first thing that I
> saw, 
> was that color saturation in all of his photos looks to me rather
> small. Some 
> photos actually look a little pastel-colored and there is some yellow
> tint in 
> quite all of his photos. Color is not completely wrong but looks in my
> eyes  a 
> little strange.
> 
> I looked at the photos XMP metadata where I found a Photoshop section.
> In this 
> section there is an entry "ICCProfile" with a value of "Adobe RGB
> (1998)".
> 
> - Does this mean that color in these JPGs is in Adobe RGB 1998 and not
> in 
> sRGB? If yes then perhaps this difference in colorspace could be the
> reason 
> for the pale colors, couldn't it?
> 
> - What should digikam actually do with a photo that is in Adobe RGB
> color 
> space?  Would it be automatically convert it to sRGB when I look at
> it? Do I 
> have to activate colormanagement in digikam to get things right even
> if I just 
> want to look at these photos?
> 
> - Can a JPG actually contain an image in Adobe RGB or is (or should
> be) the 
> colorspace by definition sRGB in all JPGs? 
> 
> I am actually unsure if I really have a color problem or if everything
> is the 
> way it should be, but since my friend does not live next door I cannot
> just 
> take a look on his monitor to see if he intended this "special" color
> look.
> 
> Thanks for your help
> Rainer
> 
> -- 
> Rainer Krienke, Uni Koblenz, Rechenzentrum, A22, Universitaetsstrasse 
> 1
> 56070 Koblenz, http://www.uni-koblenz.de/~krienke, Tel: +49261287
> 1312
> PGP: http://www.uni-koblenz.de/~krienke/mypgp.html,Fax: +49261287
> 1001312
> 
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