Could you effectively add an online "in person" check by having keybase.io send the person a large uniquely watermarked placard with a unique OCRable pin that t

Could you effectively add an online "in person" check by having keybase.io send the person a large uniquely watermarked placard with a unique OCRable pin that the person holds up while taking of photo of themselves mugshot-style that must be sent in as a lossy image type (where image tampering is detectable). With this image publicly published online, it would be easy to visually verify the person yet another way. Obviously for people with pseudonym identities that are online only, these check would be irrelevant.