#models.py
upload_path = 'images'
upload_path_to_resize = 'images/resized'


class Images(models.Model):
    image = models.ImageField(upload_to=upload_path, blank=True, null=True)
    image_url = models.URLField(blank=True, null=True)
    image_resized = models.ImageField(upload_to=upload_path_to_resize,blank=True)
    width = models.PositiveIntegerField(null=True)
    heigth = models.PositiveIntegerField(null=True)

    def clean(self):
        if (self.image == None and self.image_url == None ) or (self.image != None and self.image_url != None ):
            raise ValidationError('Empty or both blanked')

    def get_absolute_url(self):
        return reverse('image_edit', args=[str(self.id)])

    def save(self):
        if self.image_url and not self.image:
            name = str(self.image_url).split('/')[-1]
            img = NamedTemporaryFile(delete=True)
            img.write(urlopen(self.image_url).read())
            img.flush()
            self.image.save(name, File(img))
            self.image_url = None
        super(Images, self).save()

    def resize(self, *args, **kwargs):
        super().save(*args, **kwargs)
        SIZE = self.width, self.heigth)
        if self.width != None or self.heigth !=None:
        pic = Image.open(self.image.path)
        pic.thumbnail(SIZE, Image.LANCZOS)
        pic.save(self.image_resized.path)
#forms.py
from django.forms import ModelForm
from .models import Images

class ImageForm(ModelForm):
    class Meta:
        model = Images
        fields = ['image', 'image_url']

class ResizedForm(ModelForm):
    class Meta:
        model = Images
        fields = ['width', 'heigth']