The first question to ask yourself when presented with an image as evidence is this: how relevant is the image to the claim that it is intended to support. The way to do this is to pick out the key concepts in the claim, and check how many of them are depicted in the image.

Take, for example, the claim, “Fred bludgeons fish that he catches to death using his shoe”, supported by the above image of a man holding a dead fish.

First we pick out the key concepts. In this case, the claim relates to (1) Fred, (2) bludgeoning, (3) fish, (4) he catches, (5) to death, (6) using his shoe.

The image of a man holding a dead fish contains (1) a man, (3) a fish, (5) which is (apparently) dead. (4), him catching the fish, might be implied by his being by a river, but the relevance of the claim is weakened because it doesn’t depict either (2) bludgeoning, or (6) the use of a shoe.

Each of these omissions weakens the support that the image lends to the claim.

Having assessed the relevance of the image, the next thing to consider is its significance.