[argyllcms] Re: New session with EyeOnePro
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 07 Jun 2007 13:25:55 +1000
Roger Breton wrote:
The log looks relatively reasonable (although it's not converging
the way one would hope for a well behaved display). The white
point target looks reasonable.
I don't quite understand the algorithms behind dispcal but one this is clear
to me. When dispcal iterates with "Computing initial curves" and then
"Computing update to calibration curves", it is clear dispcal is iterating
to minimize some criteria. Maybe the Avg neutral error? I don't know. But it
The various numbers (color temperature etc.) create an absolute target curve
for the neutral axis (R=G=B), and it is striving to make the response conform
to that target. So this means it is simultaneously targeting the brightness,
whitepoint and neutrality. The measure the the average of the delta E squared
to the target curve.
is clear to me that, as dispcal throws its 96 patches on screen, from 1 to
96, starting with the darkest ones, the color I see on this Eizo is not
neutral at all. I don't think it comes from my instrument as I don't get bad
neutrals with other packages I use with the same instrument. But, clearly,
there is something that fools dispcal into thinking that the values it gets
from the instrument are what they are. Here's what's going on: from patch 1
to patch 96, the color progresse from black to pinkish gray to pinkish
white.
That certainly doesn't sound right. Does anything different happen
if you set a gamma 2.2 curve ?
Graeme Gill.
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