Calculations that work in After Effects but not in Premiere Pro

Question

I'm developing another Premiere Pro plugin based on AE effects SDK.
The plugin manipulates pixels in a very simple way - based on lift/gamma/gain controls it changes the values as such:
colorRGB->blue = PF_POW( colorRGB->blue , gamma) * gain + lift
And so on for the red, and green. All in floating point, PF_FpShort. I even tried doing calculations in PF_FpLong, but the results were the same.
Later the values can be clipped using MAX and MIN macros.
In After Effects everything works perfectly. In Premiere Pro, once certain gamma treshold (less than about 0.5, more than about 1.4) is reached, I start getting weird artifacts. Either green pixels or black squares in random patterns, usually, but not always, corresponding to the darker parts of the image.
I have no idea why, and how to correct it.
Please help.
EDIT: Actually any gamma that is different than 1 results in these weird artifacts, and only in the BGRA_32f mode. BGRA_8u works fine.

Answer 1

I have applied the procamp, and I am even more convinced that this must be some kind of a bug with the blue channel.
All other channels handled negative and positive values out of [0,1] range perfectly - reducing brightness in the procamp, and bringing it back in my filter works fine. Of course, all the data in the blue channel is already lost by clamping it on the input.
Which is the reason I would not want to clamp the blue channel on input, and proceed with the calculations. But so far  I have not figured out how to do it.
EDIT: Stranger and stranger...
If I clamp the assignment to the proxy pixel, it works fine:
colorRGB->blue = MAX (0, inP->blue);
But if I clamp just the value in the PF_POW macro like this:
colorRGB->blue = PF_POW (MAX (0,inP->blue), gamma.blue ) ;
or like tis
colorRGB->blue = PF_POW (MAX (0,colorRGB->blue), gamma.blue ) ;
It doesn't. It also doesn't work with pow() function from math.h, and it also doesn't work if I clamp the PF_POW from the outside like this:
colorRGB->blue = MAX( 0 , PF_POW (colorRGB->blue, gamma.blue ) );