def minpos
      v, opts = min x: true, y: true
      x = opts['x']
      y = opts['y']
      return v, x, y
    end
def minpos
      v, opts = min x: true, y: true
      x = opts['x']
      y = opts['y']
      return v, x, y
    end
Return the coordinates of the image minimum.

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