Thoughts on Wagtail image resizing

blog_post.html

<h2>{{ page.title }}</h2>

{# As 'header' is in 'sizes' for BlogPost.feature_image, this rendition will be already present #}
{% image page.feature_image header %}

{# Can also use any old filter here, does not need to be one of 'sizes', or a nickname #}
{% image page.feature_image height-200 %}

{{ page.body }}

models.py

class BlogPost(Page):
	body = RichTextField()
	
	# As a Blog.feature_image is used only in a set of known sizes,
	# on the blog index, and on the blog post page itself.
	feature_image = ImageField('wagtailimages.Image', sizes=[
		'thumnail', 'header',  # Can use nicknames here
		'width-400',  # Or just normal filter strings
	])

settings.py

# Nicknames for common sizes used across the site. Keeps things DRY.
# Nicknames could also be used as part of the lazy image resizing,
# with the generated URLs being something like `/_images/<IMAGE_PK>/<NICKNAME>/`
# and only preset nicknames being used for resizing.
# This also stops a potential DDOS attack from someone running:
#
#    for x in $( seq 1000 2000 ) ; do for y in $( seq 1000 2000 ) ; do
#	 	 curl "http://example.com/_images/1/max-${x}x${y}" &
#    done ; done
WAGTAILIMAGE_FLITER_NICKNAMES = {
	'header': 'fill-1000x200',
	'thumbnail': 'max-300x300',
}