Verification of images captured using a timestamp decoded from illumination from a modulated light source

A device comprising: an input for receiving images captured by a camera, of an environment illuminated by light from a light source; an image processing module; and a verification module. The image processing module is configured to process one or more of the images to decode a timestamp modulated into the light, and to output an indication of the decoded timestamp. The verification module is arranged to receive the indication of the decoded timestamp output by the image processing module, and based thereon to perform an at least partially automated verification of a time at which the one or more images were captured.