[Digikam-users] ICC file for Ricoh GXR

[Martin (KDE)]

Am 20.07.2012 19:35, schrieb Brian Morrison:
> On Fri, 20 Jul 2012 18:38:35 +0200
> Marie-Noëlle Augendre <mnaugendre at gmail.com> wrote:
> 
>> A camera profile wouldn't
>> be useful for that: each profile is used by the corresponding device
>> to 'interpret' the image and render it faithfully; if you're not
>> going to look at your picture on your camera (other than just for
>> checking composition, histogram, and such),  you don't need a profile
>> for it.
> 
> That is not the case, a camera profile is used to modify the colours
> saved in the RAW file when they are turned into what is displayed on the
> computer or stored in a colour-corrected TIFF, JPEG etc. 

Not quite right. The camera profile is used to transfer the data from
raw processor (after demosaicing ...) into the working colour space
(that are usually sRGB, prophotoRGB, eciRGB) which are transfered into
the display (or storage or print) colour space (sRGB, AdobeRGB ...). The
extra step with the working colour space is used to get a defined base
for further transformation.

> The profile is
> produced by looking at the colours the camera shows for a known set of
> tiles in an image of a colour target, it will be specific to the
> lighting so you need more than one profile depending on the colour
> temperature you are shooting under.

It does depend on the spectral colour distribution of your light source
and the filters and lenses you have in front of your sensor.

> 
> You will never see the corrected image on the camera's own screen
> unless you re-upload a colour-corrected JPEG to its storage.

Even then you will not see the correct colour as no camera I know of has
a calibrated display. Even if a camera would have a calibrated display
it is not exact as the environmental light differs.

Martin