Pictures speak a thousand words – and faked photographs spin awfully tall tales. Take the widely circulated image of Emma Gonzalez, a teenager who survived the Parkland school shooting in Florida earlier this year.

Gonzalez, who had been campaigning for gun control, was pictured tearing up the US constitution . Except the photo had originally shown her ripping a shooting practice target.

Such “spliced” images, where two bits of visual content are merged in a convincing and often misleading way, are rife online. But an experimental algorithm could help …