Negativity
The picture of the Shroud of Turin that we are used to seeing, the most common picture of the Shroud, is actually photographic negative of the facial image on the cloth. And yet it appears like a positive image. The lighter and darker shades of color are reversed. For instance, on the Shroud itself, the tip of the nose seems dark. But when photographed, the negative that is produced in the camera shows a nose tip that appears almost white.
This phenomenon was discovered in 1898 when an amateur photographer, Secondo Pia, first photographed the Shroud. To his complete surprise, when he examined his photographic negative (a glass-plate in those days) he discovered that it was a positive image.
This visual characteristic of the Shroud's image led some to believe that the image might be a form of medieval proto-photograph. Chemically, this cannot not so. The carbohydrate layer where the image resides is not photosensitive. And image analysis shows that the image is not the product of reflected light, which it would have to be if the image was photographic.
It is hard to imagine how a faker of relics created a negative image hundreds of years before the discovery of photographic negativity. How did he know that he had it right, with no ability to test his work. The negativity is extraordinarily precise and correct. And how did he do so by altering the chemical properties of the carbohydrate coating in which the image resides? But the big question is why?
© 2004 Daniel R. Porter, Bronxville, New York
