Direct characterization occurs when the narrator or a character in a story gives us direct information about a character.
Carver uses direct characterization when he has Bub, the first-person narrator, describe Robert:
This blind man was late forties, a heavy-set, balding man with stooped shoulders, as if he carried a great weight there. He wore brown slacks, brown shoes, a light-brown shirt, a tie, a sports coat.
This description helps us to visualize how Robert appears, which is like an ordinary, everyday, middle-aged man. Bub's reaction, which is to wish Robert wore a pair of dark glasses to fit his idea of a stereotypical blind man, indirectly characterizes Bub as someone uncomfortable with the idea of a blind person as an equal.
When Bub describes Robert's eyes as having "too much white in the iris," this is again a direct characterization of what Robert looks like, while Bub's reaction—"Creepy"—continues to indirectly characterize Bub as uncomfortable with a blind man.
In another example of direct characterization, Bub states to the reader outright that Robert does not understand what he is saying when he tries to describe a cathedral to him. Bub states, "I wasn’t getting through to him, I could see that."
This is telling us, rather than showing us, Robert's incomprehension.