They say you shouldn’t judge a book by its cover but it’s even trickier to try and search for a book by one.
Every librarian ever can tell you tales of patrons who insist that what they remember of the cover is useful and highly relevant in the information retrieval process. Invariably, we’d prefer the title and author.
Sometimes, I will grant you, the cover can be indicative of a particular edition or something. I’ve also been able to find Interlibrary Loan (commonly known as ILL) items by looking for common titles or authors in WorldCAT (a vast catalog of everything owned by as many libraries on the planet as have chosen to participate – which is quite a lot) and then showing the patrons the record, frequently with cover image, for them to recognize (or not).
However, we do not have digitally captured images of the cover of every work in our collection, not even of all the books. We also don’t have a tool for searching by cover (though I think I’ve read in the past about someone trying to develop a search engine that looks at tagged images for content and color; that could certainly be useful). So while a cover may – may - give some hints as to the contents, I wouldn’t care to bet on it.
Such is my lament.
A young man brought me the following query:
“I’m looking for a book. It was called “Christopher” and it was about a boy whose parents wouldn’t let him out of the house to go to a sleepover. It was over there [indicates the young adult (a.k.a. YA) collection]. It had a picture of a monster on the cover, with red eyes.”
Now, since I was able to turn up no even remotely related works titled “Christopher”, I’ve already run into the first stumbling block: misremembering. I’ve done it myself, of course, but it’s still a frustrating part of the search. The patron says the title is “Christopher”, but now I’m starting to think that that might be the name of the author, since he says it was on the cover. The most plausible possibility – for at least some of the information, anyway – that springs to mind is Christopher Paolini’s Eldest, which features a red dragon on the cover. Sort of close. But the patron’s sure that isn’t it and from what I know about the series, it doesn’t sound like the plot point he’s described, either. My shift is past over, by this time, so I get the patron’s information and brief the next librarian on the desk about what we’ve done for the search, so far.*
But because my brain works like this, I still haven’t let go of the question in the back of my head. Later, at home, I expound on various searches in Google (yes, I use Google; bad librarian!, I know, I know…) that I tried at the desk – “monster” “christopher” “sleepover”? No.. “christopher” “sleepover”? No… “christopher” “monster”? No…. All of these with “book” added? Still nothing. I’ve tried these in the web search function and in image search (to see if any monster faces strike a chord). I’ve tried a general keyword search in Novelist, which can serve as a plot search. Nada. I’ve tried various combinations in Boolean searching within the more robust librarian’s interface of the library’s catalog. Zip. I end up going home and typing “christopher” as a general keyword search, limited to books (since I’m not sure what the correct bracketing term is, in the patron interface, in order to limit the search to only those books whose call numbers start YA), returning 2136 works that have a “christopher” somewhere in the record. I browse these (yes, all of them) for potential monster covers, among the works that have a cover image in the patron view of the catalog. Nothing.
I reluctantly claim defeat.
And this is the second of two patrons who have asked me to find an unknown title by an uncertain author, within the hour.
I would love to be able to help you find the item you’re looking for, sir or madam, but you really must give me something tangible to work with. 
In a way, though, the real thrill of the hunt is in that magic trick – pulling off the impossible search, something from virtually nothing. My favorite story to tell about my own experience as a patron is the time when I approached a librarian, apologetically, with the request that she locate a book for me. I remembered the majority of the story, minus the title, author, and most of the characters’ names. Eyebrows up, but game, she asked me to tell her what I could.
“It was about this girl and she was also this lady knight, Britomart, I think? And someone called her Brillo-head, because she had curly red hair. But there was an evil wizard or something who was trapping her family and friends in these glass bubbles. She had a friend who had become a faun, too.”
And she found it! Enchanter’s Glass by Susan Whitcher. Magic. 
I want to be a magician.
*(I’ll be checking back in with that librarian when next I’m in, to see if anything turned up.)
