[argyllcms] Re: Continuous reading mode ambient light temperature
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 30 May 2011 11:00:20 +1000
Jos van Riswick wrote:
Reason is: I'm an artist (painter, see www.josvanriswick.nl ) and
occasionally I use photographic reference material to paint from.
So what I do is constantly compare the colors in my painting and
in the reference. Using a computer monitor seemed ideal for me,
because I can change the reference's colors to my liking, unlike
with a print. But unfortunately, the temperature of the light
outside keeps changing. So a painting that I started in the
morning, will look completely different from the image in the
monitor later in the day. I tried to use artificial light
(constant) but didn't suit me. (kind of depressing). What I tried
yesterday is just manually adjust the rgb gains of the monitor
now and then, and compare a white image to a patch of white
paint. This really makes a difference, but is kind of
cumbersome.
I understand. I'm sure it's possible, but it would need a whole
new application to do something like this. Ignoring the ICC profile
aspect and assuming that the changing calibration curves would
be sufficient, then it would need a different kind of application to what
Argyll typically provides, since you want a "daemon" type process.
There are practical details too, such as the range of color
temperatures that it would work over, and what should happen about
the display brightness.
So if you have any suggestions on how to do to the calculations
needed, or what programs I could look into, would be welcome....
The way I would imagine going about this would be to create a reasonably
accurate display profile, and then use that to create the calibration
curves for a given color temperature, brightness level and transfer curve shape.
You'd need to define the target grey axis response XYZ values, and then
use something like xicclu -ia -px -fif (or -fb if you settle for a matrix
profile)
to convert the neutral axis XYZ's to device values. These would then be the
values for the RGB calibration curves.
Graeme Gill.
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