ImageField that converts all images to JPEG on save.

JPEGField.py

import Image
import cStringIO
import os

from django.core.files.base import ContentFile
from django.db.models import ImageField
from django.db.models.fields.files import ImageFieldFile


class JPEGFieldFile(ImageFieldFile):
    """
    ImageFieldFile subclass for JPEGField
    """
    def save(self, name, content, save=True):
        image = Image.open(content)
        buf = cStringIO.StringIO()
        image.save(buf, format="JPEG")
        new_content_str = buf.getvalue()
        new_content = ContentFile(new_content_str)
        
        old_name = os.path.splitext(name)[0]
        name = "%s%s" % (old_name,'.jpg')
        
        return super(JPEGImageFieldFile, self).save(name, new_content, save)

class JPEGImageField(ImageField):
    """
    ImageField that converts all images to JPEG on save.
    """
    attr_class = JPEGFieldFile