Re: Nikon and SRGB
Re: Nikon and SRGB
- Subject: Re: Nikon and SRGB
- From: Rob Galbraith <email@hidden>
- Date: Fri, 03 May 2002 10:32:02 -0600
Hi All,
Here's some background info on Nikon's D1X that might help:
The Nikon D1X offers two colour modes, Mode I and Mode II, choosable in CSM
32. These settings determine two things:
*The look of the colour in camera-processed photos. That is, when Nikon's
colour scientists were tuning Mode I and Mode II, they had a different idea
about what the resulting colour should be. Mode I was tuned to be, in the
words of one Nikon engineer, "attractive" and "punchy", while Mode II was
tuned to be "natural." This is akin to different film stocks offering
different looks also.
*The colour space in which the processing occurs. Mode I is sRGB. Mode II is
Adobe RGB.
So, when you choose either Mode I or Mode II, you are choosing between two
different colour spaces and two different colour intentions, or looks. If
you shoot JPEG or TIFF, then you can't separate the space from the look.
Which is fine by me, since my strong preference is for the Mode II look, and
that the processing occurs within the Adobe RGB colour space is also a-ok.
In fact, for my purposes, Mode I is just about useless, but this has less to
do with its sRGB-ness and more to do with the look of the colour.
This is an important distinction to understand - when choosing Mode I or
Mode II you're choosing more than a colour space. With a different camera,
processing into sRGB might produce pleasing results. But the intertwining of
colour space and look in the D1X happens to make that not the case.
If you open a straight-off-the-camera D1X JPEG or TIFF into PS 5 through 6,
it will not have a colour space associated with it. That's because the
camera doesn't tag the files, at least not with ICC profile info, to
indicate anything about the colour space used for processing. This is
apparently because tagging a file this way is not part of the EXIF file
format used by virtually all digital cameras today.
If you open a straight-off-the-camera D1X JPEG or TIFF into Photoshop 7,
and your color settings are set to show profile mismatches, you'll see a
message that the photo has an embedded sRGB profile. This will be true even
if the camera was set to Mode II Adobe RGB. This is apparently because PS 7
is looking at the ColorSpace EXIF tag inside the file to determine whether
the file is sRGB or not. This EXIF tag offers only two choices - on, which
means it's sRGB, or off, which means its "uncalibrated" (in EXIF-speak). In
D1X JPEG and TIFF files, this tag appears to be always set to on. Hence
Photoshop's confusion.
If you shoot on the RAW setting, and then use, for example, Nikon Capture to
process the photos into finished files, you have greater flexibility. First,
there's nothing stopping you from choosing Mode II processing, but having
that processing occur from within a colour space other than AdobeRGB if you
so choose. Or choosing Mode I processing and having it occur within
AdobeRGB. You can mix and match in a way that the controls in the camera
don't permit. The resulting photo will be tagged, ICC-style, with a profile
by Nikon Capture, so Photoshop et al will have a truer idea of what they're
dealing with on open.
This is all possible, of course, because the RAW file is RAW. It's not
colour or tone-processed, and so contains the range of colour and tone
information captured by the camera. You might call this CameraRGB or
something. It definitely isn't correct to say that the D1X's native colour
space is sRGB, since it's clearly capable of recording a wider gamut of
colour than that. It is true, however, to say that sRGB is the default
colour space, since when you take a D1X out of the box it will be set to
Mode I. I suspect this has less to do with Nikon preference and more to do
with trying to adhere to an EXIF spec that heaves sRGB onto the designers of
digital cameras at every turn.
There's more to say, some of which has been said before by list poster Jack
Bingham and others, about camera-to-camera colour variation, whether the
camera does process strictly within sRGB and AdobeRGB's limits, and more.
But I hope this short summary helps some understand what Nikon cameras are
up to in a colour managed workflow.
-Rob
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