diff --git a/flatisfy/config.py b/flatisfy/config.py
index ecce0b0..e9c01ac 100644
--- a/flatisfy/config.py
+++ b/flatisfy/config.py
@@ -277,6 +277,7 @@ def load_config(args=None, check_with_data=True):
         LOGGER.info("Creating data directory according to config: %s",
                     config_data["data_directory"])
         os.makedirs(config_data["data_directory"])
+        os.makedirs(os.path.join(config_data["data_directory"], "images"))
 
     if config_data["database"] is None:
         config_data["database"] = "sqlite:///" + os.path.join(
diff --git a/flatisfy/filters/cache.py b/flatisfy/filters/cache.py
index 229d5f1..6d5de6d 100644
--- a/flatisfy/filters/cache.py
+++ b/flatisfy/filters/cache.py
@@ -86,7 +86,14 @@ class ImageCache(MemoryCache):
     """
     @staticmethod
     def compute_filename(url):
-        return hashlib.sha1(url.encode("utf-8")).hexdigest()
+        """
+        Compute filename (hash of the URL) for the cached image.
+
+        :param url: The URL of the image.
+        :return: The filename, with its extension.
+        """
+        # Always store as JPEG
+        return "%s.jpg" % hashlib.sha1(url.encode("utf-8")).hexdigest()
 
     def on_miss(self, url):
         """
diff --git a/flatisfy/filters/images.py b/flatisfy/filters/images.py
index 9c21ca8..022f537 100644
--- a/flatisfy/filters/images.py
+++ b/flatisfy/filters/images.py
@@ -17,7 +17,10 @@ LOGGER = logging.getLogger(__name__)
 
 def download_images(flats_list, config):
     """
-    TODO
+    Download images for all flats in the list, to serve them locally.
+
+    :param flats_list: A list of flats dicts.
+    :param config: A config dict.
     """
     photo_cache = ImageCache(
         storage_dir=os.path.join(config["data_directory"], "images")