Stephen Jones nicely nets it out as we try to keep up with his useful “critique of Charles Freeman’s "The Turin Shroud and the Image of Edessa: A Misguided Journey." This is part 3A and if you haven’t read parts 1 and 2 on his blog you should do so first:
But quite clearly the image on the Shroud of Turin being uniquelya photographic negative, at least six centuries before the very concept of a photographic negative was known, not onlyundermines Freeman’s case, that the Shroud of Turin is just one of many fake medieval relics: it totally destroys it!