Re: Presence of logical ones around a pixel in a certain direction and distance

If the radius stays the same for each pixel, then for a
given
angular sector, the relative offsets of the pixels to be
examined
will be the same for each pixel to be examined. One could
therefor
pre-calculate the relative offsets for each of the
angular sectors,
and then as one stepped through the various pixels, it
would become
a straightforward "add absolute index of current pixel to
relative indices and access the array at those locations"
and process
the resulting vector.

That would be true for the angles as well, and is the
method I initially considered. However the problem occurs
when you specify a point near the edge of the matrix.
Handling this case might negate any performance gains you
get by precomputing any "mask".
.

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