Re: Media Testing for maclife.de
Re: Media Testing for maclife.de
- Subject: Re: Media Testing for maclife.de
- From: Cdtobie <email@hidden>
- Date: Sun, 14 Sep 2008 22:12:31 -0400
Yes, you can view it as three points around which any color can be
defined, if the number system is flexible, so the space continues
beyond the three points. If not, it's three points between which the
numbers need to occur; clipping to the triangle. For abstract and
calculation purposes, the former is desirable. For real devices, the
latter is necessary.
C. D. Tobie
WW Product Technology Mngr.
Digital Imaging & Home Theater
DataColor.com
email@hidden
On Sep 14, 2008, at 9:33 PM, Graeme Gill <email@hidden> wrote:
MARK SEGAL wrote:
Uli, There are two colour spaces involved with Lightroom - (1) the
working space of the
application itself, which is kind of ProPhoto but with gamma of 1.0
(rather than 1.8)
in order to match the native 1.0 gamma of raw camera files; this is
hardwired; and (2)
the choice of working space gamuts for the output image exported
from Lightroom - which
is where you have the choice of three gamuts as I mentioned before.
The only default is
Actually, the color spaces chosen aren't (technically) that
important in themselves.
What's important is the range of channel values that are carried in
the colorspace
by the application, and any rendering or clipping performed when
encoding into that
colorspace.
This is because an additive tri-stimulus colorspace can use any (non-
degenerate)
three primaries as their basis, as long as there are no limits on the
channel values. Color values outside the triangle formed by the
primaries
can be addressed by a combination of negative or > 1.0 values.
Similarly
gamma encoding is irrelevant, because it can be removed when needed.
A limitation of most traditional raster format encoding is that they
can only carry values that are between 0.0 and 1.0 (encoded as a fixed
point binary, say 8 or 16 bits etc.), and so typically the gamut will
be limited to the primaries triangle, and so a gamut clipping or
gamut mapping (rendering) is forced at this point. Of course
if the raster file is intended for display on output devices
(such as displays or printers), then an output rendering is
often in fact desirable :-)
Graeme Gill.
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