Re: On the use of wide-gamut RGB working spaces [was: Photography editing spaces]
Re: On the use of wide-gamut RGB working spaces [was: Photography editing spaces]
- Subject: Re: On the use of wide-gamut RGB working spaces [was: Photography editing spaces]
- From: Marco Ugolini <email@hidden>
- Date: Tue, 07 Oct 2008 21:46:43 -0700
- Thread-topic: On the use of wide-gamut RGB working spaces [was: Photography editing spaces]
In a message dated 10/7/08 5:36 AM, Fleisher, Ken wrote:
> But that's the crux of my argument--that the file either does not actually
> have those colors in the first place, or if colors do lie in the extended
> gamut, that you cannot see what they look like on your monitor or on a
> print, and therefore if you engage in visual editing (important
> qualification), how can you know what you are supposedly preserving
> for the future?
Hi Ken.
One will not see those colors in a precise manner, but the goal is to
preserve the detail in those areas of high saturation, which is really the
purpose of the procedures I hinted at. So, though one knows that the color
is more saturated than what can be currently seen, what one can do is try
not to throw away meaningful visible transitions (detail) in those areas
that live outside the monitor's gamut.
Again, these precautions would be pointless to a user who has no desire to
push the bleeding edge of available or future printing/display technologies.
> Images from cameras that are profiled will have gamuts that are already
> limited to the gamut of the target used which will mean colors are already
> not in the extended gamut. Cameras that are not profiled will have
> unpredictable colors in the extended gamut making visual editing necessary,
> but impractical (I won't go as far as to say it's impossible, but I doubt
> that most users will to anything besides base their decisions on what they
> see on their monitor, or on a print).
It seems to me that professional photography at this point in time should
use the Raw format. A Betterlight-type workflow of the kind described by
Robin Myers (or the ongoing research on spectral capture at the Munsell
Color Lab in Rochester, NY) may eventually and substantially change the way
things are done. But for now, we're still on this side of the fence.
If I'm not mistaken (having no practical experience with it), profiling a
camera means using the camera's internal processing, the result being a
high-quality JPEG. But one will get more-flexible results using the Raw
format instead, which allows for a choice among 4 working spaces, plus a
superior control of the image's dynamic range, color temperature, hue,
saturation and many other parameters. Also, Raw offers a calibration routine
which greatly improves the end results.
Unless one is doing work in which absolute color fidelity is mandatory (for
example, catalog pictures for a clothing company), Raw would seem to me the
better route (instead of profiled JPEGs).
> I create digital captures of fine art and am certainly interested in
> capturing the full color gamut of the original.
Your line of work requires both absolute color fidelity and maximum gamut, I
agree.
> However, as I stated, I don't think the current tools allow me to accurately
> do this (not counting ColorSage type tools which I have not had the chance to
> evaluate), so I use Adobe RGB (1998) as the working color space.
I have my doubts about using AdobeRGB to capture fine artwork. If one were
to ask my opinion, I would suggest a wider color space (ProPhoto RGB being a
choice).
> I still have my raw file, so if in the future something magic happens with new
> printing technologies and I need a more extended gamut, I can always re-export
> to ProPhoto RGB and re-color correct, but I don't forsee this happening
> anytime soon.
Even using Raw may not help you much in this case, because you wouldn't
necessarily have an objective reference in the image for the color fidelity
you need. But there may be ways towards that accuracy in Raw that I don't
know about.
> True. If you are basing your color corrections on a print that has a wider
> gamut than your monitor, then by all means make sure you working color space
> includes the printer gamut, but you still won't need anything like ProPhoto
> RGB.
Unlike many people who advise against it, I do not think that there are
prohibitive downsides in using ProPhoto RGB as one's preferred storage and
editing color space, even for end uses that inhabit a much smaller color
gamut. If you use a smaller color space, knowingly or not, you have already
made decisions about mapping (or clipping, even) the (potentially larger)
gamut of the image to a smaller space.
Whether you do that from the ProPhoto RGB image or from an already
"mutilated" version of it, potentially gamut-chopping decisions must often
be made at some point in the workflow. Personally, I would rather make them
while keeping around and using the master image that contains the most
detail in areas of saturated color.
> Every user must always make their own decisions and I agree that it's
> "possible" that a ProPhoto RGB workflow for digital cameras can work for
> some people. However, I still believe that color will either be already
> clipped (calibrated camera workflow) or will be unpredictable (uncalibrated
> camera workflow) due to the inability to see what those colors
> are--ESPECIALLY if you plan to engage in visual editing, which is an
> important point.
I agree that in your case (color *accuracy* in areas of saturated color that
live outside your monitor's gamut) there is a definite problem, since you
have no definite way to check that accuracy on screen.
But for those of use who work with images that are more "flexible" (less
dependent on accuracy, which is the case for fine arts, I believe, where
near-absolute color matches are not vital), fidelity in out-of-gamut colors
is probably less important than preserving detail in them.
> But it's highly likely that there will be areas of color that make you
> fall off your seat thinking "Whoa, that's pretty horrible!"
If the image is output to devices that are not capable of reproducing the
extended gamut, then all you can do is handle effectively the colors that
are in-gamut for that device, which possibly includes colors that are
outside the display's gamut.
I believe that if (or when) the day comes that we are able to see the colors
inside ProPhoto RGB both on a display and on a print (if I live that
long...), a master file that contains those colors will still be editable in
a way that will allow for pleasing results. Some areas may appear "off" or
"strange" at first, before editing, but I doubt that they would appear
"horrible".
> The point being, you can't know what it is you are editing if there is
> no way to see it.
Which is still not a good-enough reason to throw those colors away. Not if
one has an interest in "pushing the boundaries" of available technologies,
which keep progressing -- and progress, besides other things, also
invariably means larger gamuts, both on displays and in prints.
You make edits the best way you can to the colors that you can output, and
tailor the edits to the output devices you have today. But you still keep
the wide-gamut master files around, the way you would keep an active
insurance policy in your file cabinet.
> Just because you have edited an image in ProPhoto RGB and some color may still
> lie outside of your visual editing space (i.e. monitor or print) does not mean
> those colors are what you intended them to be.
I'm not sure that I am following you, but it would seem that if the results
look good on the output device that you use today, the rest is not important
(whether you can see it or not).
> Common sense would say that, but practical application does not allow for
> it. This is why I'm excited about these new products beginning to emerge
> because this will hopefully allow what you describe to actually occur.
I see your point, because your main concern is color accuracy.
> You were very clear and I thank you for your thoughts on the subject.
Thank you for saying that, and all the best to you in your endeavors.
Marco Ugolini
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