[argyllcms] Re: White Point

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 8 Nov 2015 15:04:35 -0700

On Nov 8, 2015, at 1:07 PM, Hening Bettermann <hein@xxxxxxxxxxxxx> wrote:

The goal is landscape with a reasonable true color; and to get the best out
of the hardware (dynamic range).

In that case...

...well, first, absorb absolutely everything that Iliah has written, and
everything in all the HOWTOS and the like on the RawDigger site he linked to,
and keep at it until you know how to use RawDigger (or, perhaps, dcraw or some
other tool, but RawDigger makes life much easier) to independently do all the
stuff with your own gear and know why you'd want to do so. There's lots of very
confusing information out there about how to maximize dynamic range and do
similar stuff...but 99 44/100% of it involves kludges and workarounds and some
really crazy nonsense voodoo that's unfortunately necessary because of all the
layers that typically exist between the photographer and the data coming out of
the camera. Once you understand some very basic physics and math (especially
logarithms and exponentiation) and get your hands on the actual raw data (as
opposed to Adobe's very-much-munged mislabeled "CameraRAW" abomination), you'll
recognize all the bullshit for what it is.

But, all that writ...the profile (that, I believe, Iliah himself created)
that's bundled with RPP as the generic for your camera model is going to be
much better for your purposes than any profile you're going to create with a
ColorChecker. Variation between cameras of the same model is negligible. Lenses
are a significant source of variation, but Iliah's profiling methods are done
without a lens, so using his profile gets you a faithful rendering of the
lens's "look," which is a very reasonable thing to do in your situation.

Maximizing dynamic range basically comes down to knowing how to expose without
clipping, and, further, knowing if the scene's lighting is so extreme that you
need to resort to gradated filters or multiple exposures or lighting
adjustments or other traditional tricks of the trade to compress the scene's
dynamic range into something you can work with in post-production. Especially
if you're willing to let highlights be light and shadows be dark, modern
cameras, even those with what Internet forum trolls would have you believe are
woefully inadequate, are more than up to the task of capturing all but the most
extreme scenes with a single exposure if you use a good workflow.

Elle's documents are pretty much required for anybody working on Linux or some
other F/LOSS platform where you have to do much of this yourself, and the
majority of that carries over to OS X and Windows once you get into the image
editing arena regardless of the tools you're using for editing. But, in your
particular case, I wouldn't recommend building your own profile save as a
didactic exercise. Instead, I'd recommend RPP with its built-in profile,
exporting to your favorite working space (Beta RGB unless you know better, and
read all of Elle's stuff to learn better), and taking things from there.

Oh -- and keep the ColorChecker, and photograph it in the actual lighting
conditions anywhere you're shooting. There has never been made a better field
reference...if you've got a picture of the ColorChecker, you basically have all
the information you'd ever theoretically need for exposure and white balance
and potentially lots more. Even if you don't know all the ways you might use
it, even if you can't imagine why you'd ever care later, even though you're
likely not going to be building profiles with it...always shoot the
ColorChecker. Always.



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