Re: Microsoft's color-management claims
Re: Microsoft's color-management claims
- Subject: Re: Microsoft's color-management claims
- From: Graeme Gill <email@hidden>
- Date: Thu, 22 Sep 2005 17:15:17 +1000
Roberto Michelena wrote:
The whole idea of image-specific gamut mapping has always sound
promising, until you realize it can create incongruences between
images that contain the same elements.
Yes, it's a trade-off. If an image is only going to be viewed
in isolation, then this may be a reasonable thing.
For example take an image where an in-gamut saturated blue color
appears (a towel with HP's logo, maybe?). It happens to fit in gamut
so per the smart CMM, no compression is applied.
Then the next image contains the same towel, plus a blue sky that is
even more saturated and does not fit in gamut. So blues are
compressed.
Now HP's logo is a different shade of blue in both images. Nice
problem, isn't it?
Right, but in both cases the logo blue is as close as it can be
to the target, it just isn't consistent. What do you value most,
consistency or minimal error ? It's a case by case decision.
Interestingly, the per pixel approach addresses this problem to some
degree. Since the gamut compression is local, the logo will be treated
similarly in both cases. To preserve the "look" of the image,
such schemes try and preserve the relative color differences between
adjacent areas.
The approach is analogous to reducing the overall contrast of an image,
while simultaneously applying a large radius unsharp mask.
Graeme Gill.
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