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Author Topic: Thumbnail colours  (Read 1997 times)

Jeremy Roussak

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Thumbnail colours
« on: April 28, 2015, 12:50:16 pm »

Looking at a post here, http://forum.luminous-landscape.com/index.php?topic=99947.msg788757;topicseen#new, I find that using Safari on my MacBook Pro, the thumbnail colours are very drab, the rocks looking grey and uninteresting; but when I click on it and a full-size version appears in a new window, the rocks are red and the image is vivid. I've not seen (or at least not noticed) that phenomenon before. Is there a reason for it?

Jeremy
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digitaldog

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Re: Thumbnail colours
« Reply #1 on: April 28, 2015, 12:55:05 pm »

The thumbnail has no embedded profile or metadata defining it's color space other than 'RGB', so Safari is assuming it's your display profile instead of sRGB. Further, the image itself is in ProPhoto RGB and should be posted in sRGB.
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MarkM

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Re: Thumbnail colours
« Reply #2 on: April 28, 2015, 03:38:15 pm »

The thumbnail has no embedded profile or metadata defining it's color space other than 'RGB', so Safari is assuming it's your display profile instead of sRGB. Further, the image itself is in ProPhoto RGB and should be posted in sRGB.

It's a small detail that doesn't change the correctness of this answer, but I think Safari now assumes sRGB for mystery-meat images rather than the display profile.
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D Fosse

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Re: Thumbnail colours
« Reply #3 on: April 28, 2015, 03:59:39 pm »

"Assume" is such a vague term, it basically implies doing nothing. Does it assign sRGB? That's what it needs to do.

I'm strictly Windows/Firefox, but I've been desperately trying to get this confirmed somewhere, as I frequently try to explain to people with wide gamut monitors what to do with their oversaturated web colors. But I can't seem to get unequivocal answers anywhere...?

So...for untagged material - does it assign (as FF does)? or just quietly assume...?
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MarkM

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Re: Thumbnail colours
« Reply #4 on: April 28, 2015, 04:05:39 pm »

The appearance of an untagged image in Safari on the Mac visually matches the appearance of the same image if I open it in photoshop and assign an sRGB profile.

I have no direct knowledge of what's happening under the hood, but to me this means that when Safari encounters numbers in an untagged RGB image it treats them as if they were sRGB numbers. I'm not sure if that means it is assuming or assigning or really what the difference between those two things are. What I do know is that untagged images are no longer hyper-saturated on my wide-gamut monitor.
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D Fosse

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Re: Thumbnail colours
« Reply #5 on: April 28, 2015, 04:33:39 pm »

The appearance of an untagged image in Safari on the Mac visually matches the appearance of the same image if I open it in photoshop and assign an sRGB profile.

OK, thanks a lot. That seems to be the confirmation I needed.

The Windows version of Safari still doesn't do this. Untagged material there gets the familiar oversaturation, so testing that didn't help me. But I suspected the later Safari Mac versions got it right.
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digitaldog

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Re: Thumbnail colours
« Reply #6 on: April 28, 2015, 06:24:07 pm »

My bad, yes current versions of Safari assume untagged data is in sRGB but older versions assumed monitor RGB. I can't recall exactly when Apple fixed this, they don't document this stuff all that well. I think it was around 10.8 or there about. So depending on the version you're running, hopefully a recent version, Safari assumes sRGB.
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digitaldog

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Re: Thumbnail colours
« Reply #7 on: April 28, 2015, 06:26:45 pm »

Does it assign sRGB? That's what it needs to do.
Kind of. Assume makes more sense to me because in my mind, assigning a profile, at least using Photoshop embeds that profile. Safari doesn't. It assumes sRGB, you could say it assigns it but the image is still RGB mystery meat.
As you know, Photoshop does the same with untagged data, assuming, (assigning? not really) the working space profile selected in the color settings.
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D Fosse

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Re: Thumbnail colours
« Reply #8 on: April 29, 2015, 01:19:42 am »

Yes, I assume you're right  :)

English isn't my native language, so maybe I'm assigning meanings that aren't there  ;D
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Jeremy Roussak

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Re: Thumbnail colours
« Reply #9 on: April 29, 2015, 04:03:42 am »

The thumbnail has no embedded profile or metadata defining it's color space other than 'RGB', so Safari is assuming it's your display profile instead of sRGB. Further, the image itself is in ProPhoto RGB and should be posted in sRGB.

Thanks, Andrew.

Jeremy
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affu933

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Re: Thumbnail colours
« Reply #10 on: May 05, 2015, 07:13:22 am »

I think Safari now assumes sRGB for mystery-meat images rather than the display profile.
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