Reading and writing pixels at X,Y

Hi all;

Very new to the SDK but making great progress.

I see that using the following function, we can write pixels at a coordinate (as opposed to iterating through every pixel):

PF_Pixel *sampleIntegral32(PF_EffectWorld &def, int x, int y){

return (PF_Pixel*)((char*)def.data +

(y * def.rowbytes) +

(x * sizeof(PF_Pixel)));

}

And then we call it using:

PF_Pixel *myPixel = sampleIntegral32(*output,x,y);

myPixel->red      = 255;

myPixel->green  = 255;

myPixel->blue     = 255;

myPixel->alpha   = 255;

But how does one read a pixel at X,Y?

Thanks,

-Richard