S&V - Pages 117-118
... the partisans of the authenticity of the shroud have other arguments in reserve, quite as logical seemingly. For example when they advance that the image printed on the funerary linen behaves like a negative photographic: the sepia silhouette hardly blurred has its contrasts increased on a photographic negative. It becomes startling of realism and grows rich by details. How to consider that a forger could carry out an indecipherable work and anticipate several centuries the invention of essential photography to reveal it? Impossible, André Marion affirms, who counts among the defenders of the relic. For this specialist in the digital processing of the images, the cause is heard : the imprint cannot be painted at the Middle Ages to exploit the future concept of photographic negative...

But here is, the shroud is certainly negative... but not photographic. Because the positive one delivered by the luminous inversion does not correspond exactly to awaited « reality » attendue : it emphasizes in light the wounds, flows of blood as well as the beard, the hair and the eyebrows of the man, rigging out Jesus of a white hair. While it surrounds his contours of dark spaces. Lastly, the reversed image of the imprint should present a larger variety of intensities, in particular in the gray and the white.

The fact of having represented the man of the shroud into negative is not an extraordinary prowess : « the principle of negative was known by prehistoric men who drew their hands by transfer on the walls of the caves, the historian Paul-Eric Blanrue reminds. And then, at the Middle Ages, the imprint of the silhouette was more perceptible and did not have need for a tone inversion to be visible. »

Testify various paintings representing the shroud, as well as a lead medallion of XIV century. Besides this sign of pilgrimage which carries the first known image of the shroud reproduces distinctly the ventral and dorsal faces as well as the herringbone pattern of the linen cloth. The argument of a technical « miracle » thus does not hold...

VSD - Page 25
...To start, and without wanting to offend the former pious pilgrims, one can admit that the near total of those who saw the image between 1357 and 1897, have actually believed to see it, just like it is possible to perceive objects, persons or animals on a ink stain, a cloud or the moon. When one examines the shroud to the naked eye, one perceives indeed only a whole of stains and reddening, these last left by the flames when in 1532 the chapel of Chambery, which sheltered the shroud then, burned. It is necessary to be placed at a certain distance and under a good lighting to vaguely see the two human silhouettes whose heads are touched.

The great event happened in 1898. This year, a lawyer, Secondo Pia, photo hobbyist, obtains the authorization to take some photos of the shroud. He operates during the night, and on May 28, on his photos, appeared very visible, very clear and detailed this time, the double image of a man having been tortured. John Dieuzaide, the famous photographer of Toulouse, declared with soundness that the shroud « constitutes the first negative of the photography history ».