[Digikam-users] Showfoto and raw NEF files; Gamma and Linearity?

[Ari El]

Thanks for the hint on the workingspace... I'll definitely looks for another
one. I thought adobergb1998 was wide-gamut, but I turned out i was wrong.

On the other side, ufraw also uses lcms I believe, and  it loads the nikon
profiles with no problem. Actually digikam also loads and shows the details
of this profile. What I can't find is digikam's equivalent of the gamma and
linearity that ufraw takes as an input necessary to do the raw
conversion....

thanks!


Hal V. Engel wrote:
> 
> On Sunday 28 October 2007 20:50:18 Ari El wrote:
>> I've been using showfoto to do all my essential photo processing; I
>> started
>> to shoot raw in my nikon d80 and I'd like showfoto to do the raw
>> conversion
>> as well, since the recent versions do support color management.
>>
>> I've been playing with UFRaw and their posted D80 profile
>> (http://ufraw.sourceforge.net/Colors/Nkx_D80_5_1691_06_000_434.icm),
>> using
>> gamma = 0.45 and linearity = 0 I get really good results (in the sense
>> that
>> it looks extremely similar to the cam's generated jpg)
>>
>> Now when I open the NEF with showfoto (ubuntu 7.10 / showfoto 0.6), i am
>> presented with the color management dialog (or plugin); with it, I select
>> the above mentioned input profile, and as workspace profile I select
>> adobe
>> rgb (same thing I do in UFRaw). However I can't find the way to set the
>> gamma and linearity parameters in showfoto. The "target" displayed, and
>> the
>> result after I click OK, looks very different to the cam's generated jpg,
>> with way too much color saturation.
>>
>> I guess I'm doing something wrong in showfoto here... can someone point
>> me
>> in the right direction?
> 
> In general you should be using a profile that was created for your work
> flow.  
> That is different work flows require different profiles and using
> different 
> software means that you are using a different work flow.  
> 
> My experience with my D70 using a custom profile in UFRAW is that the
> camera 
> gamut is significantly larger than AdobeRGB-1998.  AdobeRGB-1998 has a
> gamut 
> that is about 50% of Lab and my D70 has a gamut that is closer to 70% of
> Lab.  
> So you will definitely loose some gamut and dynamic range if you do a 
> conversion to a smaller color space like AdobeRGB-1998 at least for some 
> images.  So you may want ot consider using a working space with a larger 
> gamut. 
> 
>>
>> ps. One thing I noticed is that, trying to set the default input profile
>> in
>> Settings > Configure Showfoto > Color management,  after I set the folder
>> containing my profiles, the "Input" profile options listed include a few
>> profiles I have in that folder but *none* of that folder's nikon
>> profiles.
>> For some reason my nikon profiles can not be set as the defaults. I can,
>> as
>> mentioned above, manually select the nikon input profile at the time I
>> open
>> each image.
> 
> The Nikon profile may not be correctly tagged as an input profile and
> smarter 
> dialogs for presenting lists of profiles to users will use these tags to
> only 
> show input profiles or display profiles or printer profiles when this is
> what 
> is called for.  For example, the profile widgets in LProf for selecting 
> proofing profiles do this.  So I would not be surprised if showfoto did
> this 
> as well.
> 
> Marti Maria, the author of LCMS, estimates that as many as 25% of the
> profiles 
> out in the wild have at least something that does not meet the ICC 
> specification.  Perhaps your Nikon profile is one of these.
> 
> 
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