[Digikam-devel] Colormanagement

[Peter Heckert]

Hi Paco,

fj.cruz at supercable.es wrote:
 > Hi Peter,
 >
 > My name is Paco Cruz and I'm the developer for all de color
 > management stuff.
 >
 > In this moment, digiKam has a basic color management support that I'm
 > going to explaint to you: digiKam can convert from input device color
 > profile to working or editing color profile and to output one, this
 > is, we can convert an image from camera/scanner profile to other one
 > suitable for image editing (e.g. Adobe RGB) or to printer color
 > profile. Actually, I'm working to provide digiKam with a "managed
 > view" option, using the display (monitor) color profile.
 >
Yes, please forget all, what I wrote.
I am still exploring digkam and after writing this I discovered the
global settings for colormanagement.
Ok, I was not able to use it, because it crashes or doesnt respond when
I set the input profile. So I believe, it is still unfinished code.

 > digiKam doesn't support "assign" option, only "convert" one. As far I
 > can remember now, with the first option (in photoshop) he image you
 > see in the monitor stay unchanged and with the second one,
 > the image is changed, but I'm not sure about this.

I believe, the "Assign" operation in photoline32 is equal to setting an 
input profile in digikam. It's just another name.

I understand it this way: When an image is loaded, that has no profile
embedded then the app "assigns" a default color profile and if this 
doesnt match, then the user must assign a profile manually (in pl32) or 
set the input profile manually (in digikam).

 >
 > In any way, I'm not an expert in color management and for a long time
 > I've been asking for help to get digikam a fully color managed  app
 > but looks like nobody in developer team or mailing lists have
 > experience on this stuff, so if you have this experience, I'll be
 > glad to hear what you can say me :-) .
 >

I am not an expert at all. However, pl32, while it is a windows app, it 
is a very nice program, it has two developers and they are very helpful 
to users in their discussion board and they explained to me what to do 
in order to edit images in linear colorspace.

It is commercial shareware, but you can download it at 
<http:www.pl32.com> and use it forever if you tolerate a nag screen at 
startup. If you want you can try it, it is simpler than photoshop and 
that means it is less confusing ;-)
So far I know, they also use lcms.

I find this site very helpful and informative : <http://www.aim-dtp.net>

 > PD: Excuse my poor english ;-) .
 > It is at least better than my english ;-)
 > Paco Cruz.
 >
Ok, be warned, I have a special wish for colormanagement. I already told 
this to pl32 developers, but they did not implement this until now.

Here it is:

When I load an 8 Bit image, then this is usually an sRGB image so I have 
sRGB as my default profile.

However, when I load a 16-Bit image, then this is usually a raw file or 
a selfmade tiff file and this is in linear colorspace (sRGBG1.icc).

That's my working philosophy, other people may have another philosophy.

Anyway, there are reasons to use another input space and working space 
for 8 bit images different from the working space for 16 bit images.

So it would be my wish for future versions to have different default 
colormanagement settings for 8-bit and for 16-bit images.
When an image is converted from 8 bit to 16 bit or vice versa then it 
would be fine to have a default colorspace conversion connected with 
this operation. ;-)

Ok, I understand there is a heavy time pressure for the next beta and so 
please take this as a wish for future versions, not for the next version.

P.S. I am a very beginner, presently I trie to learn how to debug a 
digikam plugin.
Still trying, only partial success, still learning...


Peter