diff --git a/invenio_app_rdm/config.py b/invenio_app_rdm/config.py
index 6b20d8aa9..a63014152 100644
--- a/invenio_app_rdm/config.py
+++ b/invenio_app_rdm/config.py
@@ -1115,7 +1115,6 @@ def github_link_render(record):
     "jp2": "jpeg2000",
     "jpeg": "jpeg",
     "jpg": "jpeg",
-    "pdf": "pdf",
     "png": "png",
     "tif": "tiff",
     "tiff": "tiff",
@@ -1142,6 +1141,9 @@ def github_link_render(record):
 ]
 """Preferred previewers."""
 
+RECORDS_RESOURCES_IMAGE_FORMATS = ["." + ext for ext in IIIF_FORMATS.keys()]
+"""RECORDS_RESOURCES_IMAGE_FORMATS must contain all possible IIIF formats to ensure their metadata is extracted."""
+
 # Invenio-Pages
 # =============
 # See https://invenio-pages.readthedocs.io/en/latest/configuration.html