[ptx] Enblend Multiresolution Spline Blender

[Ed Wildgoose]

>I'll put some more images up on the enblend web page to better describe 
>what you see on each level. I need to modify enblend to output these 
>intermediate data structures anyway so I can hunt down some ways to save 
>memory - it's using too much to stitch anything bigger than 60 megapixels 
>or so except on really big machines.
>  
>

I haven't read the details of the blend algorithm, but it is not 
possible to

a) only build the laplacian pyramid for the overlap areas,
b) blend pairs of images by calculating the blend, then flatten the 
image and do the next piece (what if three images overlap...?)

Ed W