[Digikam-users] Color management behaviour

[Giordani, Leonardo]

Hi all,

I'm definitely lost with color management, I'm experiencing a number of issues (which I'm going to describe) and I do not understand where (if)
I'm doing something wrong.

I'm using digiKam 0.10.0 on Kubuntu Jaunty.

I refer to some screenshots you can find on Picasa ath the following address: sorry for the localized interface.

http://picasaweb.google.it/giordani.leonardo/DigiKam0100KubuntuJaunty#

My color management settings are:

Monitor: eye-made profile built with lprof (Samsung SyncMaster) - it is identical to an sRGB profile
Workspace: sRGB (since my monitor is limited)
Input: Canon Profile
Rendering: Perceptual

Since screenshots describe my workflow I'll comment them all.

01. First I start with a RAW file (.CR2) made by my Canon EOS 350D

02. I open it in Image Editor and digiKam ask me about "convert" or "assign" to current workspace profile (sRGB): since the source image is RAW
I choose "convert".

03. Here is my picture: it is a bit dark since the histogram (not shown in the screenshot, sorry) is concentrated on low keys.

04. If I try to deactivate color management (with the small bottom right icon) I obtain a picture with a brown look. You can see it on screenshot
number 09, where I compared the two side-by-side.

Question 1: why, if my monitor has am sRGB-like profile, does the picture change when I activate/deactivate color management?

05. After some work I obtain the final picture.

06. I save it as JPEG (aiming for example to Web publishing) and the small preview on the left side of the screen looks different, just like the
picture with color management deactivated.

07. When I close Image Editor I see that the preview of my JPEG has that brown look I did not have in Image Editor; the same happens with Gwenview or
any other image viewer. If I open it with The Gimp it says "The image has a color profile (sRGB), convert to sRGB built-in?". Both converting and letting
the original profile result in a correct image.

Question 2: why, if the built-in profile is the common sRGB, digiKam, Gwenview and others do not see it correctly? Why Gimp can? I understand that an
application cannot implement Color Management, but this is an sRGB profile, the "de-facto" standard when no color management is active. Or not?

08. If I try to open the JPEG with digiKam it keeps asking me if I want to convert or assign the sRGB color profile.

Question 3: why does digiKam not recognize the built in profile?

10. Now I try to deactivate color management. Picture in Image Editor looks different (understandable, without camera profile).

11. After some work I end up with a picture that, when saved, viewed with Gwenview, Gimp or whatever, is always identical.

Question 4: why now every application can see my picture correctly? I tried to move them on my laptop, which has a poor monitor, and I can barely see
the differences with my main monitor both in the color-managed picture and in the other one.

Thank you very much in advance for your answers, and thank you for digiKam

Leonardo
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