Speculation that Leonardo da Vinci created the shroud
Authors Lynn Picknett and Clive Prince, in the Turin Shroud: In Whose Image (Harper Collins, NY, 1994), proposed that the shroud was an early example of photography showing the portrait Leonardo da Vinci, who created it. In this speculative scenario, the image was made using a magic lantern," a simple projector based on the camera obscura, and light-sensitive chromium salts in an egg white medium.
Leonardo da Vinci (born: 1452, died: 1519) was born more than a century after the first documented appearance of the Shroud in western Europe. Supporters of this speculation propose that the original cloth was a poor fake, for which Leonardo's superior hoax was substituted, though no historical reports indicate a sudden change in the appearance of the images.
The late Dr. Alan D. Adler, Emeritus Professor of Chemistry at Western Connecticut University, wrote in, "The Nature of the Body Images on the Shroud of Turin:"
In "Turin Shroud", Picknett and Prince, assign the image on the Shroud to Leonardo. They propose a photochemical mechanism with sunlight reflected from a statue via optics to image on sheet of cloth charged with a mixture of egg white and chromium salts. As this is an albedo image, it will fail a VP-8 test and there is no chemical or spectroscopic evidence for their chemical sensitizers. They do not deal with the blood image problem. Leonardo may rest easily in his grave.
The reference to VP-8 refers to the ability to plot the relative lighter and darker areas seen in the images and produce a three-dimensional isometric drawing of the body. With computerized virtual reality we can view the body from different angles. We can see the slope of the nose, the recesses of the eye sockets and the shape of the torso. It seems that the image is a graphic representation of the distance between any part of the body and the cloth. This is startling. You cannot do this with a regular photograph or a painting or any known type of pictorial art. There is nothing at all like this imagery in the history of art.
Historian Dan Scavone comments:
This question leads the authors to another assertion: Leonardo was a member of a secret society called the Priory of Sion, which esteemed John the Baptist over Jesus. Therefore, the apparent disembodied head visible on the Shroud man was Leonardo's cipher for the decapitated Baptist. Leonardo's use of his own photo, they argue, was owing to his inordinate vanity, the same that prompted him to encode his own face in his famous portrait of Mona Lisa, wife of Francesco de Giocondo. This theory was confirmed by Lillian Schwartz of Bell Laboratories and Dr. Digby Quested of London, who discovered that it matched up perfectly with the major lines of Leonardo's face in the above-mentioned self-portrait at age sixty. Picknett writes "Leonardo was capable of subtly building his own image into that of his masterpieces; if he had done so with the Mona Lisa, why not with the Shroud?" (It should be noted that Dr. Alan Whanger, retired from Duke University, has demonstrated that the Shroud man's face also bears strong likeness, with hundreds of points of congruence, to 6th c. icons and 7th c. coins; this essentially neutralizes the Leonardo-likeness theory.)
Unfortunately, thanks to Dan Brown and The Da Vinci Code, we are destined to live with a lot of preposterous fiction posing as history such as the Priory of Sion.
We know enough about the image chemistry from spectral analysis to know that the image was not produced with photosensitive chemicals.
