[Digikam-users] Color Mgmt: Nikon D80; Printer Profile use; GAMMAPage

[Ari El]

Thanks!

I read the documents you recommended. They really help understand the
issues.

Now I need to map some of the functionalities they mention for photoshop,
into digikam.

In my case, this first batch I decided not to shoot raw. So I have my JPEGs,
and they are in sRGB. And I have my monitor roughly calibrated to sRGB too.
Finally, I also have the printer's icc.

In the doc "Preparing Images for Delivery" the guy converts his image into
the printer's colorspace. From what I understood, the printer's colorspace
is more limited (at least in some degrees) than srgb (his monitor), so he
could actually see the gamut limitations introduced by the printer. Also
from what I understood, this is the so called "softproofing".

The question is, how do I do this in digikam?

   1- How can I change an image's colorspace? (color space assignment is
easy for raws, but how about any other image (tiff, png, jpeg). The purpose
is to follow the recommendation of Adobe's article and send the images
converted to the destination colorspace myself.

   2- Say I have a tiff image in WideGamut with the profile embedded. Again
I have the output profile already setup. How do I do a "softproof"?

   3- What does the "Use Color Managed View > Monitor Profile" configuration
do in Digikam? I am assuming that my monitor is calibrated to SRGB 2.2. Do I
have to activate this "color managed view" or not? The thing is, I'm playing
with widegamut images and this setting totally changes the tonality of my
images, shifting all to the red. The scary part is, now I have no idea what
is right, 


On the D80 icc profile I found in Bibble forums that nikond.icm appears to
be the one they use; some quick tests with bibble seem to confirm it. It is
mentioned and also posted here:
http://support.bibblelabs.com/webboard/viewtopic.php?t=6516

Just to summarize findings, other people are using NKDBase_NEF.icm  with
UFraw with Gamma: 0.45 Linearity: 0.02.
(http://sourceforge.net/forum/forum.php?thread_id=1616707&forum_id=434060)


Thanks,
Ari



Heiner Lamprecht wrote:
> 
> Hi Ari,
> 
> during Christmas, I've read through the PDF guides mentioned on this 
> list a couple of days ago.
> 
> http://blogs.adobe.com/jnack/2006/12/new_digital_photo_guides.html
> 
> They are very interesting, and some of them are dealing with CMS and 
> delivery for printing.  I recommend to read them, for this case in 
> particular:
> 
> "A Color Managed Raw Workflow from Camera to Print"
> 
> "The role of working spaces in Adobe applications" (more theoretical 
> background)
> 
> "Preparing Images for Delivery" (that's more or less your use case)
> 
> On Friday 29 December 2006 15:45, Ari El wrote:
>>
>> Now I am kind of confused on 3), what I am supposed to do with
>> the lab's printer profile? As you mention, having the Cam's
>> profile and a working profile (and a calibrated monitor) seems 
>> enough to generate a tiff for lab printing...in my own
>> colorspace. However I've been checking several pro labs (just out
>> of curiosity) and they all offer the profiles for their big
>> printers, what's the point?
> 
> What I understood from the PDFs:
> 
> The printers profile is used for soft proofing, meaning a 
> screen-preview of the final print.  Normally, the preview will look 
> quite bad, compared to the normal display.  But that's the 
> difference between the monitor and the printer.
> 
> In general, the printer's gammut is a lot smaller than the one of 
> the display.  Black is not really black but dark gray, and white is 
> light gray or slightly yellow.  The soft proof is used to identify 
> those areas of the picture, which would be out-of-gammut of the 
> printer.  With this, you can try to manually adjust the colors.
> 
> If you don't do this manually, the software in the lab will do this 
> for you.  And you will not have a chance to check this before.
> 
> Suppose all colors are inside the printer's gammut, and this gammut 
> is completely inside the workspace (e.g. AdobeRGB), it doesn't 
> matter, what profile is embedded to the image.  Both will have the 
> same result.
> 
> BTW:  I assume, the D80 is quite similar to the D100 and D200.  I 
> tried a lot of raw-converting with both of them.  Unfortunately, I 
> can not recommend to use the Linux-tools for converting.  Instead, 
> I use the original Nikon software to create tiffs, and import them 
> in digikam and convert them to (16bit) PNG.  The result is a lot 
> better, especially in terms of sharpness.  Color management is also 
> more easy, as the tiff is in AdobeRGB (I configured the camera to 
> use AdobeRGB).
> 
> 
>     Heiner
> 
> -- 
>     heiner at heiner-lamprecht dot net    GnuPG - Key: 9859E373
>   Fingerprint:  3770 7947 F917 94EF 8717 BADB 0139 7554 9859 E373
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> 
> 

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