Picture and FIle name Matching

Your file does not match what you described. Column A just has the part of the filename left of the dot, not the entire filename. See attached for a correction that takes that into account.

After re-reading your description I can't tell if you simply want to identify what's missing, or provide the actual match. Formula has also been updated to show the URL corresponding to the file name on the same line, or MISSING if not found.