Re: RIMM/ROMM and ProPhoto
Re: RIMM/ROMM and ProPhoto
- Subject: Re: RIMM/ROMM and ProPhoto
- From: Richard Wagner <email@hidden>
- Date: Sat, 4 Nov 2006 22:42:43 -0500
On Nov 4, 2006, at 9:39 PM, Chris Cox wrote:
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.
Sure, and one is a display profile, the other a print profile, one is
matrix-based, the other table-based, one gives all three rendering
intents, the other doesn't... and so on.
Thomas said that because ROMM and ProPhoto are one and the same.
Actually, he stated that "ProPhoto RGB is a simplified version of
ROMM." That doesn't sound like "one and the same" to me.
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.
The ProPhoto copyright still resides with Kodak. Although ROMM-RGB
was developed by Kodak (see the White Papers and the PICS 2000
Conference paper, March 26-29, 2000 by Spaulding et al.), the
copyright within the ROMM-RGB that ships with Photoshop is Adobe
(unlike the ProPhoto profile that ships with Adobe products, which
still belongs to Kodak).
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).
This new, V4 ROMM-RGB profile was embedded into AdobeACE... where it
resides to this day.
Then someone saw one of those V4 profiles, compared it to a V2
profile and said they weren't the same....
And they're not.
You stated earlier that, "...ROMM is normally just a matrix/TRC
profile (that was part of their design goals), so I don't know
how it could have all 3 rendering intents." Well, it does, and it's
not a matrix/TRC profile. It is not simply a V2/V4 difference.
So why not include ROMM-RGB as an output profile from ACR, since it
is used internally? ROMM-RGB still appears to be superior to
ProPhoto when converting to sRGB or other profiles where a perceptual
rendering intent is useful. As I stated earlier, 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.
The problem still exists in getting consistently good conversions
from ProPhoto to sRGB, and ROMM-RGB appears better able to do this
than ProPhoto. They are simply not the same profiles with different
names.
--Rich
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