To use django-vimage in a project, add it to your INSTALLED_APPS


And then define a VIMAGE dictionary with the appropriate key:value pairs. Every key should be a str while every value should be a dict.

    # key:value pairs


Each VIMAGE key should be a str, the dotted path to one of the following:

  • models module (i.e myapp.models). This is the global setting. The rule will apply to all ImageField fields defined in this models module.
  • Django Model (i.e myapp.models.MyModel). This is a model-specific setting. The rule will apply to all ImageField fields defined under this model.
  • Django ImageField field (i.e myapp.models.MyModel.img). This is a field-specific setting. The rule will apply to just this ImageField.

It is allowed to have multiple keys refer to the same app. Keep in mind, though, that keys referring to specific ImageField’s have higher precedence to those referring to a specific Model and any common rules will be overridden while new ones will be added.

For example, suppose you have a project structure like the following:


and my_app.models defines the following models:

from django.db import models

class Planet(models.Model):
    # ... other model fields here
    large_photo = models.ImageField(upload_to='planets')
    small_photo = models.ImageField(upload_to='planets')

class Satellite(models.Model):
    # ... other model fields here
    outer_photo = models.ImageField(upload_to='satellite')
    inner_photo = models.ImageField(upload_to='satellite')

and the keys defined are the following:

    'my_app.models': {# rules here},
    'my_app.models.Planet': {# rules here},
    'my_app.models.Satellite': {# rules here},
    'my_app.models.Satellite.inner_photo': {# rules here},

Then, all ImageField’s of my_app app (large_photo, small_photo, outer_photo and inner_photo) will have the rules defined in my_app.models dict value. However, the rules defined in my_app.models.Planet (affecting ImageField’s of the Planet model) will override the previous ones and any new will be added. The same principle applies to the Satellite ImageField’s.

In general, rules have specificity, just like CSS. This is a good thing because you can apply some rules globally and then become more particular on a per ImageField level.

The specificity is shown below:

Key Specificity
<myapp>.models 1
<myapp>.models.<Model> 2
<myapp>.models.<Model>.<ImageField> 3

The higher the specificity, the higher the precedence of the rule.

VIMAGE value

Each VIMAGE value should be a dictionary. The structure must be:

    '<validation_string>': <validation_rule>,

Each key of the dictionary should be one of the following validation strings:

Depending on the validation string, the corresponding value type (and unit) varies. The table below shows the valid key:value pair types:

Key (always str) Value type Unit
'SIZE' <int> | <dict> KB
'DIMENSIONS' <tuple> | <list> | <dict> px
'FORMAT' <str> | <list> | <dict> no unit
'ASPECT_RATIO' <float> | <dict> no unit

For example, the following (full example) rule states that the uploaded image (via the Django Admin) must be, for some reason, equal to 100KB:

    'my_app.models.MyModel.img': {
        'SIZE': 100,

The following rule states that the uploaded image must be either a JPEG or a PNG format:

    'my_app.models.MyModel.img': {
        'FORMAT': ['jpeg', 'png'],

When the value is a dict, VIMAGE uses the operator module to apply the rules. All keys accept the <dict> value type with the following strings as keys:

valid operator strings
 | Operator string         | Meaning                     |
 | 'gte'                   | greater than or equal to    |
 | 'lte'                   | less than or equal to       |
 | 'gt'                    | greater than                |
 | 'lt'                    | less than                   |
 | 'eq'                    | equal to                    |
 | 'ne'                    | not equal to                |

However, the 'FORMAT' validation rule accepts a minimal set of operators that may be applied only to string values (not numbers). That is, 'eq' and 'ne'.


Keep in mind that an error is raised if some specific operator pairs are used, for example, 'gte' and 'eq'. This is because it makes no sense for an image to be greater than or equal to something and at the same time equal to something!

Confused? Take a look at the examples.