我希望能夠調(diào)整圖像Blob的大小，然后再使用Google App Engine將其保存到數(shù)據(jù)庫中from google.appengine.api import imagesfrom google.appengine.ext import blobstorefrom google.appengine.ext.webapp import blobstore_handlersfrom google.appengine.ext import dbclass ImageModel(db.Model):    image1 = blobstore.BlobReferencePropert(required = True)class UploadImageHandler(BaseHandler, blobstore_handlers.BlobstoreUploadHandler):    def post(self):            upload_files = self.get_uploads('image1')            blob_info = upload_files[0]            blob_key = blob_info.key()            img = images.Image(blob_key = blob_key)            img.resize(width = 500, height = 500)            i = ImageModel(image1 = img)            i.put()當(dāng)然，這是行不通的，因?yàn)閕mg不再是Blob。如何將圖像轉(zhuǎn)換回Blob，然后上傳到數(shù)據(jù)庫。我不想動(dòng)態(tài)提供圖片并調(diào)整大小。我需要在數(shù)據(jù)庫中調(diào)整圖像大小。