Re: RIMM/ROMM and ProPhoto
Re: RIMM/ROMM and ProPhoto
- Subject: Re: RIMM/ROMM and ProPhoto
- From: Chris Cox <email@hidden>
- Date: Sat, 04 Nov 2006 18:39:49 -0800
- Thread-topic: RIMM/ROMM and ProPhoto
Yes, they both started out as V2 profiles, because that was the current
specification at the time that ROMM (and friends) was created.
Yes, the V4 profile was created using much newer software, because the ICC
Version 4 specification is much newer.
Yes, they "diverged" when the V4 profile was created from the V2 profile to
match the new specifications. The difference is the version -- the V4
profiles have slightly different interpretations than V2 profiles.
Thomas said that because ROMM and ProPhoto are one and the same.
The real history: Adobe wanted to include ROMM as a profile with Photoshop,
but in discussing the idea with product management and Kodak we decided that
"Reference Output Media Metric" was a bit too obscure for most Photoshop
users to grasp and "way scary" (from an alpha tester). Since the primary
goal for including the ROMM profile was to help high end photographers who
needed large gamut colorspaces - we suggested the name "ProPhoto". Kodak
did a little brainstorming to come up with a better name, but decided to use
"ProPhoto". The name was changed, the copyright updated, and the profile
shipped with Photoshop.
(I was there for the whole process, and probably to blame for the name)
Some years later, the ICC updated their specifications. Adobe updated many
of their profiles to match the new specification, and released a few of them
for wider testing (V4 profiles are still not in widespread use, and there
are some disagreements on a few of the encoding details).
Then someone saw one of those V4 profiles, compared it to a V2 profile and
said they weren't the same....
Chris
On 11/4/06 5:48 PM, "Richard Wagner" <email@hidden> wrote:
>
> On Nov 4, 2006, at 7:03 PM, Chris Cox wrote:
>
>> The version 4 versus version 2 explains the differences you're seeing.
>>
>> The ProPhoto profile was created earlier because the version 4
>> specification
>> did not exist when ROMM was renamed ProPhoto for mass consumption.
>
> So at that time ROMM-RGB was v2 as well... so ProPhoto was certainly
> not created/renamed from the current incarnation of ROMM-RGB. There
> was a clear divergence of the two profiles at some point in time.
> Even the profile creation software was different.
>
>> ROMM and ProPhoto are still the same, but the interpretation of the
>> profile versions differs slightly.
>
> It appears to be more than just the ICC version, and "the same"
> applies only in a general sense. Someone had a clear, specific
> reason for the changes between the two profiles, ICC versions aside.
>
>> Actually, Adobe uses the ProPhoto V2 profile internally in ACR.
>
> Well, Thomas Knoll has stated that ACR uses RIMM/ROMM, not a v2
> ProPhoto. Why would Photoshop install ROMM-RGB for internal use (not
> with the profiles generally available to users) if it was not used
> internally? It is also clearly Adobe's profile. I guess the best
> test would be to install a whacked-out ROMM-RGB and see what happens,
> but I haven't gone that far.
>
>> ProPhoto is not outdated, it's just a V2 profile.
>
> Fine, but it's not a V4 ROMM-RGB, either, nor does it have the
> rendering intents of ROMM-RGB.
>
>> You're making a big mountain out of a rather tiny molehill here.
>
> In addition to trying to unravel the real history behind ROMM-RGB/
> ProPhoto, I'm trying to find the best way to convert ProPhoto masters
> to other colorspaces like sRGB. RelCol conversions are often less
> than ideal. Converting to ROMM-RGB, and then to sRGB using
> Perceptual with BPC often seems to give a better conversion. Simply
> changing the output in ACR from ProPhoto to sRGB is identical to
> doing a RelCol conversion after-the-fact. The best way to get sRGB
> conversions from ACR is to specifically optimize an image in ACR for
> sRGB (this was confirmed with Thomas Knoll), but that is a lot of
> work, and it will also kill the settings for ProPhoto, as ACR cannot
> save multiple sets of settings. I don't see this as a tiny molehill.
>
> Thanks for your thoughts on this, Chris.
>
> --Rich Wagner
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