Re: Camera profiling with ICC et al
Re: Camera profiling with ICC et al
- Subject: Re: Camera profiling with ICC et al
- From: Robin Myers <email@hidden>
- Date: Mon, 15 Sep 2008 05:48:51 -0700
Hello Eric,
On Sep 15, 2008, at 02:01 , email@hidden wrote:
<snipped>
G) But lets suppose you have a given profile and you know it is
scene-referred, then you are good to go, right? Wrong, for many
reasons. Here is just one
example: No shipping camera that I know of meets the Luther-Ives
condition. The
means that cameras exhibit significant observer metamerism with
respect to
humans. So the scene-referred profile designer must decide how to
optimize the
profile. Two possible extremes: i) minimize the color differences of
a color
chart, or ii) minimize the color differences of representative scene
spectra. If
i) is chosen then the profile will perform optimally on the chart but
suboptimally (not necessarily poorly) on real scenes. Poor choice.
If ii) is chosen
then the profile will perform optimally on the scene but
suboptimally (and
frequently quite poorly) on color charts. Better choice. If you have
any doubt
about this, derive and compare the basis functions for color charts
and scene
spectra. ISO 17321 is a good place to start. There is a third
possibility
somewhere in the middle. Use a photograph of a color chart to learn
something about
the camera colorimetry but influence the profile based on scene-
spectra consi
derations. OK choice.
There is a fourth choice that I will be showing at Photokina next
week. The NDA does not let me write more until it has been publicly
shown, but if anyone wants to find out more, stop by the HP booth in
the American Pavilion and look for the Better Light exhibit.
Or, if you cannot get to Photokina, contact me after October 1 and I
should have some public information available.
Robin Myers
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