[argyllcms] Re: CC Profiles In X Specification and dispwin
- From: "Hal V. Engel" <hvengel@xxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 12 Jan 2008 16:58:19 -0800
On Saturday 12 January 2008 15:44:02 Leonard Evens wrote:
snip
> 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.
These color spaces are very likely NOT sRGB. Each device has it's own color
space. Some like a CRT monitor can come farily close to sRGB and some camera
vendors try to have the output from in camera processed images be close to
sRGB but none of these will be an exact match. Once you start using RAW
processing with tools like UFRAW the color space of these images is likely
very far from sRGB and most cameras will produce images with color spaces
that have almost twice the gamut of sRGB when you use a RAW workflow. This
is also true for film scanners.
>
> 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.
Typically these tables will be in video memory since this is used during the
digital to analog conversion that is done by the video cards onboard DAC. In
most cases these tables are fairly small with 3 tables of 256 16 bit entries.
On some cards these might be somewhat larger.
> It was my
> impression that under X, the information is not actually loaded into the
> video card memory. Am I right?
No
Hal
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