Well, I have no clue, and as I said it seems to be a 50/50 stale-mate between proofs of proponents and deniers, but Luigi Garlaschelli seems to have a valid way how to reproduce it. Also, I’m inclined to believe the first recorded mention of the shroud made by Catholic Bishop Pierre d’Arcis in 1389 in a letter to Clement VII, “Eventually, after diligent inquiry and examination, he discovered how the said cloth had been cunningly painted, the truth being attested by the artist who had painted it, to wit, that it was a work of human skill and not miraculously wrought or bestowed.”