A method and a system generate a transactional visual challenge image to be presented to a user thereby to verify that the user is human. For example, an image module generates a visual challenge to be presented to a user as part of a challenge-response to verify that the user is human. A transactional background image module identifies a transactional background that is associated with a specific transaction and a combiner image module combines the visual challenge and the transactional background into an image which is to be presented to the user during transaction authorization, the transactional background associating the visual challenge with the particular transaction.