[argyllcms] Re: CC Profiles In X Specification and dispwin

On Sat, 2008-01-12 at 23:17 +0100, Gerhard Fuernkranz wrote:
> Leonard Evens wrote:
> > I clearly still don't understand some things, so please be patient with
> > me.  Just what is the distinction between the calibration" and
> > "profile". I looked at my profile with iccdump, and it contains a
> > whole lot of information with the last three tags being rTRC, gTRC, and
> > bTRC.
> >   
> 
> Only the VCGT (video card gamma table) tag in the ICC profile contains
> the "calibration" information which will be loaded into the device.

Thanks.  That clarifies things quite a lot.
> 
> All other tags are "profile" data, i.e. color characterization data
> describing the behavior of the device (as it behaves with the
> calibration loaded). The tags rTRC, gTRC, and bTRC are part of the
> "profile" information too. They are not loaded into the graphics card,
> but I guess they could be used to set the XDCCC_LINEAR_RGB_CORRECTION
> property for XCMS.

I get the general idea, but it would be clearer if you could give an
example of how the description of the behavior might be used?  For
example, it might help me if I understood what happens to a given
pixel's triple of values starting with its value in an image tiff file,
and what does what in that connection. when an applicationsuch as gimp
or eog displays that pixel on the screen.  There may also be some other
conversions connected with specifying a color space and a triple in that
color space such that the pixel is now represented by a "color" which is
specified in a device independent manner.  I think that in what I'm
doing under Linux, using Vuescan to scan. possibly ufraw for my digital
camera, and editing in gimp, that this color space is sRGB.  But I must
admit I'm very hazy about all that.

Also, there is one aspect of this that always confuses me.  The
information can either be loaded into the actual video card memory or
into a table in the computer memory that X uses before sending data to
the card, or I suppose some combination of the two.  It was my
impression that under X, the information is not actually loaded into the
video card memory. Am I right?  If so it might be a misnomer to say it
is loaded into the graphics card, but I suppose in the end it might not
make any difference.

Thanks again for all the responses.  Perhaps in time I can reciprocate
by helping others.


> 
> Regards,
> Gerhard
>

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