An interesting problem

Aaron Trevena aaron.trevena at
Thu Jan 4 08:51:58 GMT 2007

On 03/01/07, muppet <scott at> wrote:
> Essentially, for each neighborhood size, you sum an entire
> neighborhood once, and then add and subtract only deltas from there.
> To avoid resumming at the next row, you move in a serpentine fashion
> through the image / matrix / table / whateveryoucallit.  The output
> of this exercise is, of course, another image whose size is original
> size divided by neighborhood size.

A good implementation of 'serpentine fashion' is hilberts space
filling curve, as it would allow you to traverse the grid without
cross your own path or having gaps.

I wrote a C++ and Perl implementation a few years ago as I found it
rather fascinating, and the algorithm is quite trivial.


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