Now, at first the reader just thinks “Oh, he means ‘concise.'” That goes well with “short” and starts the same and has the same vowel sound in the second syllable as “contrite.” Easy correction.
A second look, though, brings the confusion. What is “short” imagery? What is “concise” imagery? Does the student mean that, Hemingway-like, the author uses imagery sparely and in short, stark sentences? This is an appealing idea, but “short” and “sparse” are completely different concepts and therefore not particularly compatible yokemates.
Or does he mean the author limits imagery to generic object-names and single-word adjectives and adverbs and to one-for-one similes and metaphors, rather than epic similes, extended metaphors, conceits, and elaborate descriptive passages? William Carlos Williams rather than Edgar Allan Poe?
What if he does indeed intend the word “contrite”? How can an image grieve over its sins? Or how could a writer use an image in an apologetic manner?
A reconsideration of the first, easy, top-of-the-head correction leads to the realization that I just don’t know what he means, and I can’t make up anything—unless we’re talking the Williams/Poe kind of thing, which I have only a little confidence in.