[Digikam-devel] raw problems

[Arnd Baecker]

On Tue, 4 Sep 2007, Gilles Caulier wrote:

[...]

> 2007/9/4, Arnd Baecker <arnd.baecker at web.de>:

> > - The histogramms for RAW and JPG differ considerably
> >   (for the raw one all its weight is near small values).
>
>
> Important point in general :
>
> - RAW file are container :
> => RAW image data
> => metadata
> => JPEG preview image
>
> This is want mean than RAW include a JPEG file ! This one is used to display
> RAW picture very quickly on tv screen using camera device. This picture is
> very similar than if you use your camera in RAW+JPEG mode, excepted than
> JPEG image embedded in RAW is generaly smalless than a real JPEG picture
> taken directly.
>
> In digiKam we use this embeded JPEG image to render thumbnail and display
> preview of RAW files if no whole image is used for that

Yes, and they look essentially the same

> (check setup)

Yes, with setting:  "Embedded preview load full image size"
the colors are different
(the raw one appears much more green).

> About histogram, RAW and JPEG histogram differt. It's normal : this is not
> the same picture (in the same color space: JPEG = sRGB, RAW = linear).

I perfectly understand.
But from the users point it looks confusing:
two images which appear to be the same in the thumbnail view
have completely different histograms.
How do other programms deal with this?

I had another look at the handbook:
http://docs.kde.org/development/en/extragear-graphics/digikam/using-iccprofile.html
about using ICC profiles.
Looking at the second diagramm, I would think that
non-RAWs should never get into the color-management workflow?

Why do I then get for normal JPGs
> ("This picture has been assigned a color profile that does not match
> with your default workspace color profile.
> Do you want to convert it ..." - current workspace profile
> is said to be AdobeRGB - not sure where I defined that.

Anyway, nothing urgent at all from my side, just
would like to understand and use it at some point ... ;-)

Many thanks,

Arnd