sRGB or Adobe RGB?

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<p>Where are you deriving this white point data from? Colorsync Utility?</p>

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<p>ICC profile inspector</p>

<blockquote>Wonder if this is a bug within i1Match 3.6.2 or maybe OS 10.4.11</blockquote>

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<p>Operative system has nothing to do with a monitor profile.</p>

<p>Well, I can confirm this 'wtpt' tag has nothing to do with the color shift converting to sRGB.</p>

<p>I examined the tags of several color working spaces and canned iMac display profiles within Colorsync Utility with some having 6500K and others like ColorMatch with 5000K according to their 'wtpt' tag and I also converted to them in Photoshop. On closer inspection all changed slightly in varying degrees with ColorMatch being even worse than both sRGB profiles according to what I saw in the preview and Apple's DigitalColor Meter. An orange that read in ADM as 255,138,0 shifted to 255,138,54 in ColorMatch where as sRGB shifted to 248,138,41. The one that changed the least visually and in ADM was my i1Display iMac profile.</p>

<p>The only major difference between all of these profiles according to Colorsync Utility were their 'chad' tag>Chromatic Adaptation Matrix number readouts.</p>

<p>Still don't know what causes this.</p>

<p>Just to make this orange color shift more clear I've screencaptured and overlaid three conversions of two orange swatches that noticeably shift converting to other profiles with the i1Display iMac showing no shift and the other two ColorMatch and sRGB changing slightly in hue/sat and a bit of luminance.</p>

<p>This image is tagged with the i1Display iMac profile. It was converted from ProPhotoRGB where the original orange swatches were created to my iMac profile where I then drag and dropped the screencaptures of the other two oranges into the i1Display iMac space.</p><div></div>

<p>Quote myself</p>

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<p>Tim,<br /> some numeric values using your monitor profile:<br /> - transforming ProPhoto(195,120,20) into sRGB, you get (255,116,0)<br /> - transforming ProPhoto(195,120,20) into your monitor profile, you get (255,115,0)<br /> (same as the to sRGB transform)<br /> But:<br /> - transforming sRGB(255,116,0) into your monitor profile, you get (249,114,39)<br /> That color is the "the orange flowers dulled"</p>

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<p>Computing the dE2000 between (255,115,0) and (249,114,39) using the monitor profile, I get 3.35 (not a very bad value).<br>

Perhaps you cannot get a better value with your monitor and your calibration kit.</p>

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<p>Thanks for computing the Delta E on those numbers. The actual conversion numbers between converting from ProPhotoRGB to sRGB and my i1Display profile may be close but the appearance of the previews aren't.</p>

<p>I don't know if you were measuring the Delta E of the actual converted data or the differences of the two previews.</p>

<p>Can you visually see the differences in the above image? The dulled sRGB version is 249,114,39 the reading I get in Apple's DigitalColor Meter when I should be getting 255,116,0 if the colors are suppose to look the same regardless of the color space converting to. That's how color matching and color management is suppose to work at least on a display.</p>

<p>I was under the impression this kind of color shift which resembles gamut clipping should only occur converting to narrow gamut printer spaces like CMYK and minilabs, not synthetic matrix based profiles.</p>

<p>The difference is for the two RGB values in your monitor color space.</p>

<p>Tim, the problem is that going from ProPhoto values to sRGB, with this color, you are at sRGB gamut boundary.<br>

The same is true going from ProPhoto to monitor gamut.<br>

But sRGB value is slightly inside monitor gamut.<br>

All the transforms are relative, so the sRGB value is not changed when you translate it into monitor color space.<br>

As the corresponding monitor color space value is more inside, it is more "desaturated".</p>

<p>Try V4 sRGB profile to transform from ProPhoto to sRGB , using perceptual intent.<br>

I think you can have some benefit.</p><div></div>