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"Tagged" with a color profile v. "Embedded" color profile

Richard Clarke , Dec 23, 2010; 07:02 a.m.

My file has been "tagged" with a color profile. A color profile is "embedded" in my file.
Two ways of saying the same thing?
Thanks.

Responses

Howard M , Dec 23, 2010; 08:12 a.m.

My hunch is that someone (Andrew?) will be more detailed in possible differentiation of the terms but I think the answer is 'yes'. The RGB values are essentially scaled for whatever color profile it's in. This is why PS's 'convert to profile' is the thing you want to do 98% of the time vs. it's 'assign profile'. Convert tags the file and changes the RGB values whereas assigning simply changes the tag but leaves the RGB values alone. You can see that by finding on the web different files of the colorchecker chart in various colorspaces.

the classic problem is that w/o the tag, the display device doesn't really know how to correctly interpret the numbers. This is why non-color mangaged applications like Internet Explorer screw-up so badly (since it assumes everything is in sRGB)

Mark Sirota , Dec 23, 2010; 08:52 a.m.

No, these are not the same thing, so many web sites treat them as such.

There are EXIF/DCF tags for color space. One is called ColorSpace, which can be used to tag sRGB. Another is InteroperabilityIndex, which can be used to tag Adobe RGB (1998). No other color spaces can be tagged. These are what digital cameras use to indicate the selected color space.

Also, an entire profile can be embedded in the XMP data. This is what Lightroom does. Lightroom does not use the tags.

Howard M , Dec 23, 2010; 09:16 a.m.

Oh man, I hate being wrong ;)

Andrew Rodney , Dec 23, 2010; 12:51 p.m.

Two ways of saying the same thing?

Yes (in terms of ICC profile use).

Mark Sirota , Dec 23, 2010; 03:36 p.m.

Well, I'm glad we've cleared that up. :-)

There are definitely two separate concepts -- color space indicated by EXIF/DCF metadata, and an embedded profile. Some files have one, some have the other, some have neither, some have both. And the difference matters, because some readers will prefer or ignore one or the other.

We can differ over whether the term "tagged" really means one or the other or both. I think there needs to be terminology to describe both, and I think "tagged" and "embedded" have historically been those terms, despite many usually authoritative people and sites saying otherwise. Andrew, do you have other terms you use to describe the difference?

Why it matters: I did an experiment a few years ago where I created files which had all permutations of the tags and embedded profiles, and sent them to a few minilabs to be printed. At the time I was trying to prove that it was important for Lightroom and similar tools to tag the files in addition to embedding the profiles, but to my surprise what I found was that some minilabs ignored the tags anyway (which is a real problem for those shooting Adobe RGB JPEGs in camera, then sending them directly to a printer.) It's been a while, and it may be worth trying that experiment again, with more labs this time.

Andrew Rodney , Dec 23, 2010; 03:58 p.m.

An image can have an embedded ICC profile and is thus tagged. The OP asked about a color profile. That’s an ICC profile that is embedded into a document. But yes, there is a different concept in terms of mainly camera generated JPEGs that have some EXIF data that defines two possible color spaces. DCF is pretty limited in options here for good reason. And yup again, some labs are completely clueless about color management and embedded profiles.

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