code: public static void render(List<Contour> contours , int colors[] , BufferedImage out) {
  
  		colors = checkColors(colors,contours.size());
  
  		for( int i = 0; i < contours.size(); i++ ) {
  			Contour c = contours.get(i);
  			int color = colors[i];
  
  			for(Point2D_I32 p : c.external ) {
  				out.setRGB(p.x,p.y,color);
  			}
  		}
  	}
docs: Renders only the external contours.  Each contour is individually colored as specified by 'colors'
  
  @param contours List of contours
  @param colors List of RGB colors for each element in contours.  If null then random colors will be used.
  @param out (Optional) Storage for output