MADAM – A definition in your glossary is incorrect (ATG No 2382). Strictly, the terms verso and recto apply to books, meaning the left and right pages. Certainly they don’t both apply ‘to the back of a picture’.
Picture cataloguers commonly use verso for the back and recto for the front of a picture.
I’ve always thought that just plain wrong: if we must appropriate terms, wouldn’t it be fitter to filch from the numismatists, not the bibliographers – so, obverse for the front of a picture and reverse for the back?