Re: Photography editing spaces
Re: Photography editing spaces
- Subject: Re: Photography editing spaces
- From: Klaus Karcher <email@hidden>
- Date: Thu, 09 Oct 2008 11:55:26 +0200
Hi Ken et al.
I'm a bit late to the show as I was quite busy in the last few days.
Maybe some of my arguments have already been produced by others -- anyway:
Fleisher, Ken wrote:
I personally have an issue with visual color editing in a large color space.
Me too. For me an additional reason or me is that many controls in
Photoshop are to coarse in huge working spaces like ProPhotoRGB, e.g.
moving a point on a curve by only one tick can be too much and one has
to use tricks like adjustment layers with reduced opacity to accomplish
corrections with sufficient precision.
[...] The argument for using a larger color space, such as
ProPhoto RGB, is that you retain the larger gamut of your original scene and
you don¹t have to compress the color into the smaller gamut of your working
color space. This is supposed to make any future conversions more accurate
if we develop devices that can later reproduce the additional colors
contained in the wider gamut.
However, in my opinion, when you edit in ProPhoto RGB you are not getting
what you think you are getting.
You are perfectly right IMO. But as decent printer gamuts exceed the
monitor gamut in many regions, there is no other chance than cycling
through several rounds of costly and time consuming "blind" corrections
and subsequent test prints to get the print matching the original.
Limiting the gamut to sRGB is no viable alternative IMHO.
[...] 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?
If you are using e.g. an EPSON x880, a large portion of the printable
gamut is not representable in sRGB.
Also pure cyan, many saturated greens and some reds and yellows are
printable in standard sheed fed offset but not representable in sRGB or
ordinary display gamuts. Therefore I'd say even though it's impossible
to asses those colors on screen, it would be false to clip them off in
the source file.
[...] When we calibrate our
cameras (for those of us who do), we use a target like one of the
ColorCheckers. What this means is that the color gamut of our input is now
restricted to the color gamut of the target and any colors outside of the
gamut of the target are essentially undefined. So, even if you export to
ProPhoto RGB from your camera software, all of the colors are already
restricted to the gamut of your target, which, as you may have guessed by
now, is no where near as large as ProPhoto RGB. Once again, the advantages
of a large color space will not be realized.
That's not quite correct: the profiling target does not limit the gamut
of the input device. The profiling software has to extrapolate the PCS
values for colors outside the profiling target gamut. That means, the
precision of the profile decreases in this regions, but the colors won't
get clipped as long as they are in the device space of the input device.
With HP/BetterLight¹s new ColorSage solution (and the solution that Eric
Walowit has recently discussed) we seem to now have a way to characterize
our input directly into a large color space and have the correct color
without any visual editing. This is the only way that it makes any sense, to
me, to use something like ProPhoto RGB with camera captures. Until I see how
these solutions perform, I can¹t really say if that is working yet or not.
What I've seen at the Photokina was quite impressive :-)
(There was nothing on cold not archive with conventional methods, but
ColorSage does it apparently at first go and does not requre hours of
manual tuning (even worse: *blind* tuning in many cases on ordinary
displays)
[...]
Therefore, I believe that there is no point in using a working color space
that is much larger than your monitor¹s color gamut if you are making color
editing decisions of your digital camera captures based on the visual image
on your screen--or a hardcopy print of it for that matter. ProPhoto RGB and
other large gamut color spaces are great as containers for images that need
to record the full color gamut of a wide gamut scene, but ONLY if there
doesn¹t need to be any visual color editing.
I've build a compromise working space for one of my fine art clients:
it' based on the primaries of Bruce RGB, has a L* TRC and D50 white
point. It covers nearly all printable colors on decent ink jet printers
and substrates as well as all scanner targets. On the other hand, it is
still small enough to be feasible for Photoshop. One can even work in 8
bits per channel as long as one has not to make too drastic corrections
or has to deal with super-smooth gradients.
Klaus Karcher
--
Klaus Karcher * Eichenallee 18
26203 Wardenburg * Germany
Tel. +49 441 8859770
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