pygame包中的image类提供了许多图形转化的方法：

1.pygame.image.frombuffer(string, size, format):          return Surface
        create a new Surface that shares data inside a string buffer

2.pygame.image.fromstring(string, size, format, flipped=False):        return Surface
        create new Surface from a string buffer

3.pygame.image.get_extended():        return bool
        test if extended image formats can be loaded

4.pygame.image.load()=pygame.image.load_extended()

       pygame module for image transfer

5.pygame.image.load(filename): return Surface
   pygame.image.load(fileobj, namehint=): return Surface
        load new image from a file

6.pygame.image.save(Surface, filename): return None
        save an image to disk

7.save_extended(...)
        pygame module for image transfer

8.pygame.image.tostring(Surface, format, flipped=False): return string
        transfer image to string buffer