python image - ignore values in resize

[Lie Ryan]

Travis Kirstine wrote:
> I have be attempting to resize (downsample) a RGB image using the
> python image library resize function.  Everything works fine but I
> would like to exclude black values 0,0,0 from the calculations.  I
> have tried creating a alpha mask based on black values then performing
> the resize but that only create partially transparent tiles in the
> regions that had black values

Crop the image first.