Django custom template filter that replaces 'img' tags with 'amp-img'. The img tags must have 'height' and 'width' attributes for validated AMP output.

django_filter_amp.py

from django import template

register = template.Library()


@register.filter(name='amp')
def amp(value):
    """
    Usage:
        {{ article.body|amp }}
    """
    import re
    value = re.sub(
        r'<img src="(.+)" alt="(.+)"/?>',
        r'<amp-img src="\1" alt="\2" layout="responsive"></amp-img>',
        value,
    )
    return value