[argyllcms] Re: Scanner RGB Primaries Off the Chart
- From: Ivan Tsyba <ivantsyba@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 17 Jan 2013 00:18:19 +0200
Input devices, such as scanners and cameras, do not have gamut. Gamut
is a characteristic of output devices, such as displays and printers.
For example: your camera can capture every pure spectral color
(stimulus) on single image (if you shot such scene) - virtually camera
have no gamut. To store that image, RGB primaries of it's profile must
be far away from spectral locus (RGB triangle must encompass locus).
In practice, I think, there can be some limitation. Hope, somebody
give you more detailed answer.
2013/1/16 שחר קלינגר <sklinger@xxxxxxxxxx>:
> Hey everyone,
>
> I managed to create my first scanner profile using Argyll, an Epson 10000 XL
> scanner and an IT8.7/2 target that was supplied with it. I created a
> shaper+matrix profile, and overall, I believe the profile is behaving well.
> Something that completely baffles me is the RGB primaries coordinates. I've
> opened the resulting profile in ICC's Profile Inspector, and looked at the
> coordinates plotted against the xyY horseshoe. The green and the blue are
> completely off the chart (Gx:0.265 Gy:0.848; Bx:0.121 By:0.00291). What I
> don't understand is how can that be, what does it actually mean regarding the
> scanner's response, and how does Argyll get those coordinates from the
> scanned TIFF which obviously cannot reproduce these colors?
> The color expert that works with me thought this was some kind of bug, but
> after I opened the generic scanner profile supplied by Epson that showed
> similar coordinates, he couldn't provide an explanation.
>
> Thanks for your help,
> Shahar Klinger
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