Re: GaMapICC v0.5
Re: GaMapICC v0.5
- Subject: Re: GaMapICC v0.5
- From: Marco Ugolini <email@hidden>
- Date: Wed, 27 Jan 2010 04:39:32 -0500 (EST)
Graeme Gill wrote:
>I doubt that image specific gamut mapping is going to do anything
>special with your particular image.
Graeme,
Regarding my image, I was showing a difference in results using image-specific gamut mapping, which in my opinion (a) makes the image overall too light and (b) loses some detail in the indicated red area.
>It's gamut almost looks like it's already been clipped
>to the destination space (or very near),
My inspection of the file in ColorThink Pro reveals that the red areas are up to 8 DeltaE 2000 outside the gamut of the destination profile. Eight DeltaE 2000 is not very near.
See the 3D graph at <http://tinyurl.com/y8f26je> .
(The colored points represent the contents of the original AdobeRGB image file; the white wireframe indicates the boundaries of the destination CMYK profile.)
>and there are no interesting colors that are not of a similar hue to colors
>that lie on the gamut surface. Given the nature of it, a colorimetric
>mapping will look pretty close to the original. Image specific
>gamut mapping shows an advantage where there are colors in an image
>that are within the destination space gamut, but have a similar hue
>to source colorspace colors that lie outside the destination gamut.
Am I to understand that image-specific gamut mapping actually works less well when colors are better-differentiated to begin with? How does that help?
Even by the standard of better differentiating colors that are near in hue, I don't detect an improvement for those in the GaMap image.
>I've done a trial with typical settings I'd use (after fixing a glitch
>in the image gamut code that Klaus drew to my attention), and also created
>a soft proof back in AdobeRGB space here <http://www.argyllcms.com/Axe.zip>,
>and while there are some differences to your result, it all looks rather
>similar.
I disagree. The proofed AdobeRGB file looks different enough from my source image to be noticeable. If that is what you meant to say.
I also fail to see what proofing the image back to AdobeRGB aims to prove.
In any case, the CMYK files are the only ones I really care about, because they represent the results that would go on press, i.e., the results that the client would have to like enough to pay for. A comparison between the CMYK conversions made with GaMap and with the "regular" Photoshop conversion (when compared to the "look and feel" of the original) still shows a visual advantage for the "regular" Photoshop conversion (better definition, better contrast, better detail, even better saturation).
Marco Ugolini
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