premise: Man in a blue shirt with a mustache talking on a cellphone. hypothesis: Man in a purple shirt with a beard is talking with friends.
contradiction: The shirt cannot be both blue and purple. It would be odd that the man is identified by his mustache in one instance and beard in another but they are not technically contradictory. It would also be unusual for a man to be talking on a cellphone (implies one person at a distance) and talking with friends (implies multiple people near one another)  but the man could theoretically speak with another group on speakerphone or be on a conference call so they are not technically contradictory.