def maxpos
      v, opts = max x: true, y: true
      x = opts['x']
      y = opts['y']
      return v, x, y
    end
def maxpos
      v, opts = max x: true, y: true
      x = opts['x']
      y = opts['y']
      return v, x, y
    end
Return the coordinates of the image maximum.

 @return [Real, Real, Real] maximum value, x coordinate of maximum, y
   coordinate of maximum