The term for making letters/words unreadable in photos is to "Greek" them (so there's no unintentional presentation of trademarked words, for example). I wonder if that comes from "it's all Greek to me." Which in French is "it's all Hebrew to me," so would the equivalent term in French be to "Hebrew" them?
(Of course, I've always found this ironic, since my Greek is pretty much non-existent (beyond what any mathy person has figured out about Greek letters), and my Hebrew is relatively decent, depending on the context. My French has varied over the years...)