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Subject: Re: Presence of logical ones around a pixel in a certain direction and distance
Date: Tue, 13 May 2008 00:07:05 +0000 (UTC)
Organization: Timothy S. Farajian, Inc.
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> 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".