So you have a crawler, but you don't want it to cache images, just the page.

cache-but-not-images.py

from cachecontrol import CacheControl
from cachecontrol.caches import FileCache
from cachecontrol.heuristics import BaseHeuristic

class NoImagesHeuristic(BaseHeuristic):
    def update_headers(self, response):
        if response.headers['Content-Type'].startswith("image/"):
            return {
                'cache-control': 'no-cache',
            }
        return {}


sess = requests.session()
cached_sess = CacheControl(requests.Session(),
                           heuristic=NoImagesHeuristic(),
                           cache=FileCache('.webcache')