Re: Camera Raw
Re: Camera Raw
- Subject: Re: Camera Raw
- From: Graeme Gill <email@hidden>
- Date: Thu, 27 Feb 2003 12:40:14 +1100
tlianza wrote:
>
"I guess I'm surprised that Adobe chose this D65/A scheme as
>
the basis for camera profiles (although it has practical
>
advantages)."
>
>
I personally think that Adobe is listening to photographers. D65 is an
>
imperative because of the sRGB spec. Like it or not, each manufacturer of a
>
sensor provides an sRGB transfer matrix based upon least squares spectral
>
analysis of the sensor or phyisical testing. Naturally, tungsten (nominally
>
illuminate A) is a common source in many venues including stage, film and
>
television, so as Graeme wrote, there are plenty of practical advantages.
My though was that a more fundamental way of characterizing
a capture device is by measuring its spectral sensitivities and
opto-electronic conversion function (on the assumption of
course that the device behaves predominantly in a channel
independent manner). Given this information it should be
straightforward to convert from high dynamic range device
values to high dynamic range CIE values (or at least
"most likely" CIE values if it doesn't meet the luther
condition).
On the other hand, maybe shooting a couple of standard
test charts under illuminants A and D65 is a lot easier than
measuring the spectral response. (Of course there are ways
to approximately measure the spectral response of the device by
shooting a test chart composed of materials having a variety
of different spectral characteristics + different spectral
illuminants, and doing some fairly tricky maths.)
Graeme Gill.
_______________________________________________
colorsync-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/colorsync-users
Do not post admin requests to the list. They will be ignored.