How does Django determine if an uploaded image is valid?

Question

I'm trying to add images to my models in my Django app.

models.py

class ImageMain(models.Model):
"""This is the Main Image of the product"""
    product = models.ForeignKey(Product)
    photo = models.ImageField(upload_to='products')

In development mode, every time I try to upload the image via Django admin, I keep getting:

Upload a valid image. The file you uploaded was either not an image or a corrupted image.

The jpg I'm trying to upload can be viewed with os X Preview so it would seem to be valid.

It seems the problem is Python Imaging Library doesn't recognize it as an image. Why would that be happening with a valid image?

PIL is installed, verified via the Django shell.

Answer 1

According to Django's source code. Those three lines are responsible for verifying images:

from PIL import Image
trial_image = Image.open(file)
trial_image.verify()

The image type could be unsupported by PIL. Check the list of supported formats here

Answer 2

I looked into the Django source, in django/forms/fields.py, in the ImageField class. Django actually does use PIL to determine when an image is valid.

Answer 3

Did you try uploading image format like gif or png? It might be that your PIL was not built with the jpeg lib properly. I had a similar issue with Django on Ubuntu. If you have ever seen the error message decoder jpeg not available, check this link. Relevant line from the link:

$ cd libImaging
$ ./configure --with-jpeg=/somelib/lib --with-zlib=/somelib/lib