If the artist saw the operson and painted him then it has very high possibility of similarity. On the other hand, if an artist has not seen the person and just heard about him then then any paiting about that person will be just 'imaginative' and has no association to the actual person but symbolically. But please note that these paitings do NOT even have symbolic representations because of half a dozen differences and illusions I mentioned in my talks. The difference include the kind of dress, seat, turban, chinese looking face and many many more (look above in my talks or otherwise dont throw those questions which have been answered already, please).