Search OneSearch, the FIT Library's online catalog, using a word or phrase describing your topic and adding the phrase "pictorial works" or "in art" to find books that are highly illustrated.
For example: stores will get you books that might have some photos, charts or illustrations, but stores pictorial works will list those that are the most heavily illustrated.
"Mythology in art" will definitely find illustrated books; "mythology" books might be mostly or only text.
In the OneSearch record for a book, the field marked "description" might indicated "plates", "ill." or "illus." (illustrated or illustrations) and "chiefly ill." means the book is mostly visuals.
Of course for some topics--such as designers, artists, art movements--virtually all the books in the FIT Library contain images, so don't worry if you can't find anything labeled "pictorial works".