title: Algorithm for spread-out 2D point distribution
body: <p>In a 2D pixel array, I need an efficient algorithm that will select p% of pixels that are the most spread out.</p>
  
  <p>This can be done adaptively by selecting points, then repeatedly adjusting the positions of points that are too close together.  But this isn't efficient since it would require many iterations and distance calculations.</p>
  
  <p>It doesn't have to be perfect, it just needs to avoid point clusters as much as can be done efficiently.</p>