1👍
You can check this in form clean methods:
def clean_picture(self):
# check image weight
image = self.cleaned_data['picture']
if image:
if image.width > 100:
raise forms.ValidationError(_("Selected image is too wide"))
return image
There is also height attribute. You can access name of the file in ImageField, get extension from it and validate it like I did with width.
Source:stackexchange.com