Django上传图片生成成缩略图的类

from PIL import Image
from cStringIO import StringIO
from django.core.files.uploadedfile import SimpleUploadedFile
class Photo(models.Model):

#from sharejs.com
title = models.CharField(max_length = 100)
image = models.ImageField(upload_to ="photos/originals/%Y/%m/")
image_height = models.IntegerField()
image_width = models.IntegerField()
thumbnail = models.ImageField(upload_to="photos/thumbs/%Y/%m/")
thumbnail_height = models.IntegerField()
thumbnail_width = models.IntegerField()
caption = models.CharField(max_length = 250, blank =True)

def __str__(self):
    return "%s"%self.title

def __unicode__(self):
    return self.title

def save(self, force_update=False, force_insert=False, thumb_size=(180,300)):

    image = Image.open(self.image)

    if image.mode not in ('L', 'RGB'):
        image = image.convert('RGB')

    # save the original size
    self.image_width, self.image_height = image.size

    image.thumbnail(thumb_size, Image.ANTIALIAS)

    # save the thumbnail to memory
    temp_handle = StringIO()
    image.save(temp_handle, 'png')
    temp_handle.seek(0) # rewind the file

    # save to the thumbnail field
    suf = SimpleUploadedFile(os.path.split(self.image.name)[-1],
                             temp_handle.read(),
                             content_type='image/png')
    self.thumbnail.save(suf.name+'.png', suf, save=False)
    self.thumbnail_width, self.thumbnail_height = image.size

    # save the image object
    super(Photo, self).save(force_update, force_insert)</pre>