1. A computer-implemented method of processing a visual query performed by a server system having one or more processors and memory storing one or more programs for execution by the one or more processors, the method comprising: at the server system: receiving a visual query from a client system distinct from the server system; performing optical character recognition (OCR) on the visual query to produce text recognition data representing textual characters including a plurality of textual characters in a contiguous region of the visual query, and structural information associated with the plurality of textual characters in the contiguous region of the visual query; scoring each textual character in the plurality of textual characters; identifying, in accordance with the scoring, one or more high quality textual strings, each comprising a plurality of high quality textual characters from among the plurality of textual characters in the contiguous region of the visual query; retrieving a canonical document that includes the one or more high quality textual strings and that is consistent with the structural information; and sending at least a portion of the canonical document to the client system.