Review of the paper

Giulio Fanti and Roberto Maggiolo, The double superficiality of the frontal image of the Turin Shroud, Journal of Optics A: Pure and Applied Optics, no. 6, pp. 491--503, June 2004. PDF

The conclusion of the paper: there is a superficial image on the back side of the Shroud similar to the one on the front side. This has been concluded after a computerized analysis of photos taken during the 2002 restoration of the Shroud. This was not concluded from a direct analysis of the back side of the Shroud. (Such access is jealously guarded for a very few number of people closed to the Archdiocese of Turin. Even the digital images taken in 2002 are not made available to outside researchers.) The superficial aspect of the image is important. It mainly means that the authors concluded that the image they detected on the back side is not due to some fluid that would have seeped through the Shroud from the front side; but is similar to the superficial image clearly seen on the front side -- therefore the title of their paper containing the terms "double superficiality".

It is important to assess the implications of such possible superficial images on the back side of the Shroud. Their presence may support the hypothesis that the Shroud images were formed using a heated bas-relief; on the other hand, their absence almost disprove this technique. In any case, the purpoted back side images found by Fanti and Maggiolo are so faint that it makes this technique unlikely. And the absence of obvious (i.e., naked eye) visible images on the backside is easily observable from the 2000 and 2002 photographs.

Section 5 of that paper explicitly gives the reasoning behind the conclusion of "double superficiality." We quote the most relevant paragraph:

"Since the body image on the fs [front side] is superficial (Weaver 1980, Pellicori and Evans 1981, Schwalbe and Rogers 1982, Jumper et al 1984, Jackson et al 1984, Adler 1999, Rogers 2002, 2003), and an image on the bs [back side] exists, the central part of the fabric was clearly not involved in the creation of the image—i.e., the internal part of the linen fabric does not have an image."

This reasoning is correct if the locations of observed superficiality on the front side corresponds to image locations seen on the back side. But there is no evidence of such a correlation in the paper. On the front side, there are clearly some "image" locations which are produced by blood or other fluids. And there are image locations, probably the largest total surface, that are due to a superficial coloration. But unfortunately there has never been a systematic study to separate these locations -- and the paper does not site any reference that gives precise locations. So, the conclusion of superficiality is unsupported. That is, most of the "image" perceived on the back side could simply be due to fluids that seeped through the cloth.

Table 1, p. 499 of their paper, lists eight sections of the back surface face compared to the front surface of various other photographs. The sections are identified as "Moustache", "Nose tip", "Nose", "Eyes", "Hair, left", "Hair, right", "Eye, right" and "Eye, left". The comparisons are based on the S scores given by Equation 1 of p. 497 of their paper. It is stated that a score higher than 0.6 demonstrates a good match to declare them similar.

But there are at least two main problems with the results of Table 1:

  1. Each image section is not described in terms of sizes and locations. Some of these sections (e.g. eyes, nose tip) might have small surface which would be dubious since small sections have a tendency to have a large score S. It also makes it impossible to reproduce these results.
  2. The matching process from the back surface to the front surface of these sections is not explained in details which raises the possibility that the researchers selected themselves the sections to match, which is very subjective. Actually, from the partial explanation given for Fig. 12, it appears that the matching process was done based on finding the maximum matching value in the same region. This is a very dubious approach since that has a tendency to maximize similarity independently for each section. We can even see in Fig. 12 that the matching "window" for the moustache and nose is tilted. A single global match for the entire face should have be done and then each corresponding section should have been compared (evaluating the factor S) using that single match.

Moreover, at the 2005 Dallas conference, during the public question period, I asked Monsignor Ghiberti and Dr. Mechthild Flury-Lemberg, who directly saw the back side of the Shroud during the 2002 restoration, if any images could be seen on the back side. Their answers were clearly negative. Have they looked very carefully to detect superficial images? I do not know, but their answer leaves a major doubt since the detection of images by Fanti and Maggiolo was done by indirect means. Of course, printed photographs of the backside were made available to the general public -- from which we cannot see any obvious images -- yet they are not of a high enough resolution to clear up the matter.

Overall, the main problem -- certainly of no fault from the researchers -- is the Shroud could not be directly studied to prove the superficiality of the image on the backside. This study of Fanti and Maggiolo is clever; but such a study could be much clearer, simpler, and conclusive by careful (microscopic) direct observation on the backside of the Shroud. Unfortunately, the backside has been hidden away by a new backing cloth.

There are probably some digital macro-scanning, done in 2000 and 2002, that could answer these questions; but they have not been made available. And these images could be used to answer many other questions.

The necessity to conserve the Shroud is very important -- and one step in that direction is to do systematic very high resolution digital scans of the front and backside of the Shroud. Such scans could result in hundreds if not thousands of gigabytes of data. For example some large sections of the Shroud should be digitally scan with a resolution of one pixel per 0.01 millimeter or even at a higher resolution. Essentially, every speck of blood, or other very small debris could be visible. It would then be possible to definitely and clearly answer numerous questions that have been raised over many years -- without accessing the Shroud. It would cetainly settled the present study done by Fanti and Maggiolo -- and many others (e.g., which part of the Shroud has apparent blood residue). Some digital scans have been done in 2000 and 2002 -- but they are not available to most researchers.