Colour Management... Help!

[Mark Greenwood-2]

Hi All,

My first post to the list and I'm sure it's a recurring theme. I'm very impressed with Digikam, it has a very nice workflow and all the tools I need. But enough crawling.. :) I have a question. I work mostly in JPEGs and sRGB, but I've been recently shooting in RAW. I've read the documentation and done lots of research, I understand what ICC profiles are and why colour management is important, but I still don't understand how digikam is handling my RAW files. I hope you don't mind if I ask a few questions.

Firstly, my flatscreen monitor is factory calibrated to sRGB, and my camera produces JPEGs in sRGB so I haven't been using colour management up to now.

But today I shot some RAW files so, from the Settings dialog I've enabled Colour Management. I have 'Use colour managed view' disabled. The profiles I have selected are:
Monitor : sRGB
Workspace : sRGB
Input : Nikon D40 (downloaded from the website link given in the pdf. I actually have a D60 but I think they're very similar)
Soft Proof : I have the correct profiles for my printer but I'm not printing yet.
Black Point Compensation is off and Rendering Intents is Perceptual.

I don't think I've changed anything under the 'RAW Decoding' options apart possibly from 'White Balance', which is set to 'Camera'.

So, I have an album of RAW files (.NEF) straight off the camera. The embedded previews look bright and saturated. When I open the image editor I get a bland, unsaturated image with very little contrast. The docs lead me to believe this is expected and I think I understand why.

However, this is the bit that has got me confused.... now I go to Colour->Colour Management. Under 'Input Profile', 'Use default profile' is selected. If I now change that to 'Use selected profile' and browse to the exact same profile that I selected in the Settings dialog (the Nikon D40 one) all of a sudden my image has saturation and contrast. If I now change 'Workspace Profile' from 'Use default workspace profile' to 'Use selected profile' and browse to an sRGB profile I have downloaded I get even more saturation and contrast. If I now adjust the white balance to D50 instead of D65 I get something pretty close to how the embedded preview looks. But shouldn't all that be happening automatically if I have colour management enabled?

So what's going on? It looks to me as though Digikam is not applying my default profiles when it imports the RAW files, and that I would have to go through the Colour Management step for every file. What have I missed?

Finally, if I go back to using JPEG files, do I have to change the colour management settings so the input profile is sRGB?

Many thanks and sorry for the long email,

Mark
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[Milan Knížek]

Mark Greenwood píše v Pá 31. 07. 2009 v 00:23 +0100:

However, this is the bit that has got me confused.... now I go to Colour->Colour Management. Under 'Input Profile', 'Use default profile' is selected. If I now change that to 'Use selected profile' and browse to the exact same profile that I selected in the Settings dialog (the Nikon D40 one) all of a sudden my image has saturation and contrast. If I now change 'Workspace Profile' from 'Use default workspace profile' to 'Use selected profile' and browse to an sRGB profile I have downloaded I get even more saturation and contrast. If I now adjust the white balance to D50 instead of D65 I get something pretty close to how the embedded preview looks. But shouldn't all that be happening automatically if I have colour management enabled?

So what's going on? It looks to me as though Digikam is not applying my default profiles when it imports the RAW files, and that I would have to go through the Colour Management step for every file. What have I missed?

Finally, if I go back to using JPEG files, do I have to change the colour management settings so the input profile is sRGB?

Many of these things are known and  already reported as bugs
https://bugs.kde.org/buglist.cgi?quicksearch=digikam+color+management

For the time being, I would recommend to follow the status of these bugs and avoid using CM in digiKam. According to other posts here, Gilles plans to have a look at this topic before 1.0.0 final release. (You can use UFRaw to convert NEF files to sRGB in the meantime.)

regards,

Milan Knizek
knizek (dot) confy (at) volny (dot) cz
http://www.milan-knizek.net - About linux and photography (Czech language only)

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