Re: Gamut Clipping converting from NKAdobeRGB to AdobeRGB
Re: Gamut Clipping converting from NKAdobeRGB to AdobeRGB
- Subject: Re: Gamut Clipping converting from NKAdobeRGB to AdobeRGB
- From: Nicholas Androulidakis <email@hidden>
- Date: Fri, 24 Dec 2004 11:55:23 -0500
Here are the notes Richard posted some time back on this issue. I used his technique for renaming the actual Adobe RGB file, and have had no problems since.
Quote follows >>>>>>>
For those who want the "real" Adobe1998 profile embedded in their files
(and not the Nikon "equivalent"), it's relatively easy to do without
resorting to PS to assign (or "null convert") profiles. This has no
functional significance, other than to decrease confusion among those
receiving the files who might otherwise think that the profiles are
significantly different.
The Nikon Adobe1998 (aka NKAdobe.icm) and bone fide Adobe1998.icm files
are very similar, but they are not exactly the same. Nikon, for some
inexplicable reason, left out the "Media black-point tristimulus" setting,
which should be 0,0,0. Everything else is essentially identical to the
bone fide Adobe file. Therefore, instead of modifying the Nikon file to
have the correct non-Nikon, pure Adobe name inside (but with incomplete
media settings), use a copy of the real Adobe1998 file to replace Nikon's
file (NKAdobe.icm). Rename the copy of the Adobe file to NKAdobe.icm and
replace Nikon's version. It should work fine, as Nikon's software is just
looking for a profile with the correct name.
Make sure to watch out for other, similar-sounding files (e.g.,
%_NKAdobe.icm, etc.) that should NOT be replaced or modified.
I haven't verified the file names on the Windows NV, but the same
technique should work.
End Quote >>>>>
Nick
Nicholas Androulidakis
email@hidden
On Dec 24, 2004, at 11:37 AM, Richard Wagner wrote:
Doug,
I'm no Guru, but here goes:
I shoot RAW with the D1x and almost always choose Mode II or Nikons
equivalent to AdobeRGB as the intended destination working space.
As do many of us...
If I
understand this whole thing, the RAW CCD dump gets converted from the
camera via Nikons proprietary input profile and spits out the resultant
processed image in the Nikon 4.0.0.3 Adobe RGB (NKAdobe.icm or
something like that) which is essentially the same as AdobeRGB.
My understanding is that Nikon Capture renders the image into what is essentially AdobeRGB (1998). The resultant TIFF is tagged with the Nikon version of AdobeRGB that you described above.
Further, it has been noted in several places that Nikon had dropped the
media black point tristimulus tags from all the standard color space
profiles (sRGB, Bruce, Wide, etc.). Don't know why. In all the
standard color space profiles, the media black point tristimulus is set
to 0,0,0 so I doubt that omitting it is a big deal, since it's likely
that the CMMs assume values of 0,0,0 if the tag is missing.
Correct, and I agree. I tried playing with this profile in ColorThink recently, which is what led me to discover the apparent color shifts in ColorThink when converting from Adobe to Adobe... (See Steve Upton's excellent response.) For what it's worth, the "preferred CMM" is also different (NKON vs. ADBE).
Further, Further.....Wait.....But no client has this Nikon profile
(well most clients anyway).
Agreed, and it leads to lots of phone calls, e-mails and hassles... Too bad Nikon had to muck things up.
So to make things normal I have always done a 'Convert to Profile' into
chosen my Working Space profile AdobeRGB. This is a RelCol transform
as Steve mentions above. No other option.
Here's where we differ. Instead of converting, since the profiles are essentially the same, I ASSIGN the Adobe profile. It will then be recognized by Photoshop, clients, etc. as the "real thing." No rounding errors, etc., either. I'm away from the office now, so I can't check my notes at home, but it's also possible to rename a copy of AdobeRGB as the file that Nikon uses and get Nikon Capture to embed the correct (i.e., non-Nikon) profile. Capture merely looks for the correct filename. I'll send more on this later if you're interested. I would NOT "convert to profile." Assign is a better choice.
Would going from one essentially same size container to another via
RelCol clip colors? Aren't these essentially an exact overlay?
There should be no clipping - only rounding error - since Photoshop apparently does not recognize this as an essentially null transform.
Hope this helps.
--Rich
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