On Aug 9, 2005, at 12:09 PM, John C. Randolph wrote:
If you try moving the sliders, you'll see a couple of unexpected
results.. the first and most obvious one is that the red curve is
affected by the green value. The second is that if I set any of
the inputs to 0.5, the peak of the corresponding curve is
apparently lower than the midpoint of the output image.
I don't get the R/G interaction here, all the curves look right.
System Profile says this is a GeForce FX 5200 AGP.
Interesting.. I hadn't thought of it being a hardware or driver
issue. I see the problem on my 17" PB, which has a Mobility Radeon
9600. I just tried it on my G5, which has a GeForce 6800 Ultra card,
and I'm still seeing a red/green coupling but it's much more subtle.
BTW, if you're reading this, Pierre.. Is the output of the gradient
patch supposed to be linear?
Ok, I'll chalk this one up to an ATI driver issue.
I do see the low peak, though. It looks like inside CI the gradient
starts at 0.3 when the input is 0.5, though Pixie says the value on
screen is indeed 0.5. Gamma, maybe? 0.5 ^ 1.8 is pretty close to 0.3.
Hmm.. The peaks are correct for me on the GeForce 6800.
Well, thanks everyone for the help. Good to know I hadn't just lost
my mind. I think I need to drop by Apple's compatibility lab and try
a few more GPUs.
-jcr
John C. Randolph <email@hidden> (408) 914-0013
Roaming Cocoa Engineer,
Available for your projects at great Expense and Inconvenience.
