python manage.py thumbnail cleanup
This cleans up the Key Value Store from stale cache. It removes references to images that do not exist and thumbnail references and their actual files for images that do not exist. It removes thumbnails for unknown images.
python manage.py thumbnail clear
This totally empties the Key Value Store of all keys that start with the settings.THUMBNAIL_KEY_PREFIX. It does not delete any files. The Key Value store will update when you hit the template tags, and if the thumbnails files still exist they will be used and not overwritten/regenerated. This can be useful if your Key Value Store has garbage data not dealt with by cleanup or you’re switching Key Value Store backend.
python manage.py thumbnail clear_delete_referenced
Equivalent to to clear but first it will delete all thumbnail files referenced by the Key Value Store. It is generally safe to run this if you do not reference the generated thumbnails by name somewhere else in your code. As long as all the original images still exist this will trigger a regeneration of all the thumbnails the Key Value Store knows about.
python manage.py thumbnail clear_delete_all
Equivalent to to clear but afterwards it will delete all thumbnail files including any orphans not in the Key Value Store. This can be thought of as a more aggressive version of clear_delete_referenced. Caution should be exercised with this command if multiple Django sites (as in SITE_ID) or projects are using the same MEDIA_ROOT since this will clear out absolutely everything in the thumbnail cache directory causing thumbnail regeneration for all sites and projects. When file system storage is used, it is equivalent to rm -rf MEDIA_ROOT + THUMBNAIL_PREFIX