Re: ProPhoto RGB an ROMM-RGB in Photoshop
Re: ProPhoto RGB an ROMM-RGB in Photoshop
- Subject: Re: ProPhoto RGB an ROMM-RGB in Photoshop
- From: Marco Ugolini <email@hidden>
- Date: Fri, 25 Aug 2006 11:47:26 -0700 (GMT-07:00)
In a message dated Aug 25, 2006 8:25 AM, Richard Wagner wrote:
>First off, the paper that you cite, while interesting, never mentions
>or compares ROMM RGB with ProPhotoRGB - in fact, ProPhoto is not
>mentioned at all.
That is an early paper. One needs to draw one's own conclusions from it.
>Secondly, if you physically compare ProPhotoRGB and ROMM RGB, they
>are not the same profile! Take a look - you'll see.
With apologies to Julius Caesar, I went, I looked and I did compare, using the ProPhoto RGB tags viewed in ColorThink on the one hand and the published ROMM RGB specs on the other, right next to one another.
>They are in many ways similar, but they have dissimilarities
>that can account for the differences originally noted by Klaus when
>making conversions.
Same gamma. Same chromaticities. Same white point. In its "Device mfg desc tag", ProPhoto RGB even spells out "KODAK"!
You are stating that they are different, but fail to say *what exactly* is different.
What else could cause the unspecified difference you mention? It may be that the default rendering intent is not the same, perhaps, though I believe that ColorThink uses the Absolute Colorimetric intent to graph profiles anyway, so that should not matter. Another possible difference has been mentioned, whereby ProPhoto is a monitor-type profile, while ROMM RGB is said to be a printer-type profile. I am unable to verify whether this reflects factual reality, but, if this is the case, how would that account for a difference in gamut and/or conversion behavior, given all those other exactly matching elements?
>Drop them both in the Profile Inspector of
>ColorThink Pro. One and the same - not!
Yes, I do not have a copy of the ROMM RGB profile on my system (please send me a copy of it offline, if you can), and all I have to go by are the published specs. I'll be very curious to verify these stated differences after I get to view the actual profile in ColorThink.
Regards.
-------
Marco Ugolini
Mill Valley, CA
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