Monday, January 30, 2012

Turin Shroud - beware computer-corrected and/or otherwise manipulated images

I've previously drawn attention to those images of the Turin Shroud that are described as having "3D-encoded" information.  They make it sound as if there is something mysterious, almost supernatural-like about the man depicted.

In fact the computer merely scans the digitized image for light and dark regions, and then "raises" the light and "lowers" the dark to create a 3D relief.

Yes, we are told that ordinary photographs and paintings do not respond in this fashion, but the fact that the 1532 burn marks do should be sufficient to show that there is nothing unique about the image of the crucified man. Anything, late-acquired burn marks included,  that gives tonal contrast is interpreted as differences in relief and displayed accordingly. There may well be intensity differences that are related to 3D properties in the original image, but they are not selectively processed, nor does the computer tell you anything about how the image was formed on the cloth (beware explanatory diagrams that show a sheet of linen held above a picture of a crucified man, suggesting projection across space with no lens or other imaging system shown).


In fact there are many aspects of the Shroud image that are hyped in my view, often misleadingly so as to suggest paranormal phenomena, and others that are strangely overlooked, or at any rate, rarely commented upon.

A particular one that bothers me right now is the size disparity between the ventral (front) and dorsal (rear) image.Why should there be a size disparity if the v&d images on the shroud are from the same subject or representation thereof?

Here's one picture that accompanied a Daily Mail article that made the point well, but was strangely not commented upon in the article:


Ventral and dorsal images of the Turin Shroud (photographic positives)


Now I don't know about you, dear reader, but I would have said the dorsal image was considerably taller than the ventral, agreed?

Being a retired science bod an' all, I did not take this one picture on trust, so accessed a Google image file that showed the entire shroud opened and displayed full length, and used the  photoediting function on my MS Office to place d&v side by side:

My DIY job on comparing those two views - ventral and dorsal

You won't believe the hassle this elicited on another site. I was accused of computer trickery, in particular for aligning the two images feet upwards (or sideways). In fact, MS Office chose to do that with no help from me. And it seems a reasonable assumption that both images end in feet, and are not truncated at some other level. But who knows what different people see or do not see in those faint sepia orignals:( I have been chided for not seeing toes, but as hard as I try I am never able to discern anything that are unequivocally toes, and when folk say I am blind I am reminded of the tale of the King who was in his "altogether") .

Here's an exercise anyone can do. Enter Turin Shroud into a Google image file and look for any side-by-side images of the original. In going through the first 15 pages or so, I have counted about 6, and all WITHOUT EXCEPTION show the dorsal image as taller than the ventral.

Then go to the multi-author paper by Fanti et al (2005) ,  and there you will see the difference confimed quantitatively.They say right away in the Introduction that the ventral length is 1.95 metres, and the dorsal is 2.02 metres, making a difference of 0.07metres, which is a very considerable 7cm.


Nobody has made a song-and-dance about that difference before - so why do I get beaten up for pointing out something that is both obvious at a quick glance, and confirmed quantitatively? Might it be something to do with having acquired the label "sceptic" on whom it is open season for the true-believers (or anti-science bods)  to browbeat and belittle?

But it does not end there. I have been told to go and consult a "real science" paper ("15 pages" no less, as if papers were judged by their length), and in case I fail to do as told, there is a diagram from the paper, showing how a computer analysis of the front and rear images reveals that the two are "superimposable" (sic) and entirely "consistent" (the term was in fact "compatible", but let's not quibble over semantics. Either way I have been told by a science teacher  to go back to school. (I used to be a science teacher myself once - to A-Level and beyond, but never mind).

 These image are described as "superimposable" (Well yes, almost anything is superimposable if you bend up an end or two here and there).


Well, what do you know? The two images are "superimposable", provided you line up at the head end, and overlook the small matter of the feet being in different places. So how was that conjuring trick performed, in such a way that a 7cm difference in length vanishes?  Was it  a muscular spasm in a supposed cadaver that kept the toes extended when measuring the dorsal length but conveniently turns them up when measuring up the ventral?

It's achieved my friends with computer "re-imaging" of course, and as always where computers are concerned, one has to look carefully at each and every assumption that is programmed in if one is to avoid the dreaded "GIGO" syndrome that so afflicts the world of megabyte jiggerypokery.

Let's do that, shall we? Let's go through that paper with a toothcomb, and see how the conjuring trick was performed that either adds 7 cm to one length or subtracts it from the other (take your pick).  Or does it add 3.5 cm to one length, and subtract it from the other? Anything to do with the paper in question is in blue.

Computerized anthropometric analysis of the Man of the Turin Shroud

Giulio Fanti, Emanuela Marinelli and  Alessandro Cagnazzo (1999)

Source? (found via Google Documents). Appears to be "Proceedings of the 1999 Shroud of Turin International Research Conference, Richmond, Virginia"


Abstract

For the development of the anthropometric analysis of the Man of the Shroud through vision
systems an anthropometric research integrated with experimental researches was realised.

OK so far


The images of the Man of the Shroud were acquired and numerically elaborated to point out
the outlines of the two imprints (frontal and dorsal) and to carry out the measurements.


Numerically elaborated?  I don’t care for the sound of that. Sounds somewhat reminiscent of a 'with-profits' life-assurance quotation.


The dimensional results obtained were therefore corrected in consequence of the systematic
effects found, like for instance those due to the cloth-body wrapping effect.

Corrected? For cloth-body wrapping effect?  When did you see an actual body wrapped in the Shroud?  Photographs please.


The height of the Man, 174±2 cm, was therefore measured with different techniques and the
results obtained were compared with the anthropometric indices derived from bibliography.


Hallelujah. That systematic 7cm difference in length has been reduced to a +/-  2cm error bar.  Isn’t it  wonderful what one can do with computers?

That’s just the abstract. Let’s delve further into the “real science”:

 Oh, here's the conclusion to the abstract:

"From the comparison among the anthropometric indices characteristic of different human
races and those of the Man of the Shroud it was shown that the Semitic race is the closest one
to the Man’s features."

Bless!



"Even if at first sight the task doesn’t seem hard, it is necessary to overcome some
difficulties: it must be observed that it is not enough to define two characteristic points such as
the top of the head and the sole of the feet, and then to measure the distance between them. It
must be considered that the cloth was wrapped around a man not lying completely flat, but
rather with his legs flexed and his head bent forward."

Er, how do you know it was a man, a real one that is, and not a statue?  How do you know he was lying not completely flat, but with legs flexed forward?  Oh yes, we are to “consider” that. Maybe  you meant “hypothesize”. Maybe it’s Google that has mistranslated “hypothesize” as “consider”. The omens are not auspicious, but let’s withhold judgement and read on.

Oh, and y.ou also seem to be assuming that rigor mortis set in while still on the cross, for the head to be tilited down, even when laid supine,  and for the knees to be locked up, and that rigor mortis  was still there several days  later on Resurrection (assuming that an imprint did not occur initially over 3 days, but in a sudden flash on resurrection). Never mind. let's press on.


"The length of the body image must then be corrected, considering these effects and the fact
that the cloth was not in contact with the whole body. For instance, the intensity variations of
the image just next to the knee on the dorsal image and below the calves on the two imprints,
frontal and dorsal, confirm the absence of such a contact."

The length needs to be "corrected". You don't say (well, you do, which is more the pity). How do you know you are not "uncorrecting" the length by introducing tendentious claims that the imprint was left by a real crucified man, and one moreover that was still in rigor mortis, or at any rate wrapped up so tightly that the initial posture was retained even after the muscles had relaxed? This is starting to look like Mickey Mouse science, of which there is a surfeit already in the so-called "scientific" Shroud literature.

"Till now, the studies carried out have been based on more or less subjective hypotheses
admitted also in consequence of the thesis that the various authors tried to show: some
researchers favourable to the authenticity of the Shroud are inclined to provide the lowest
values for the height, while those who are anti-authenticity are inclined to provide the highest
values."

Ah, we are still in the Results section and you are starting to question the objectivity of others. Should you not be keeping that for Discussion.  You would not have been allowed to get away with that when I refereed papers for the Biochemical Journal etc.   And lo and behold there is a red exclamation mark against the yellow security  "padlock" icon that says "Beware. contains unauthenticated content". Surely not. This  paper came recommended from a school science teacher as "real science", 15 pages no less, and we are still only at page 2.

"The authors who believe the Shroud is false claim that the Man of the Shroud, about 1.80 m
height, was a giant compared to his contemporaries and therefore it wouldn’t have been
necessary for Judas to give him the famous kiss to point him out in the group. However from
recent excavations made in Rishòn Letziòn [2] it is evident that many Canaanitic men were
very tall: many of them reach 1.75 m"
Ah, so it's now clear why you are interested in height. You want to show that the Man on the Shroud  was from the right part of the world. This paper is nothing to do with whether there is a size discrepancy, or whether the image was from a man or an inanimate object. And we are still in the Results section...


PARAMETERS CHARACTERISTIC OF THE POSITION OF THE MAN OF THE
SHROUD

By carefully observing the legs on the dorsal image, the intensity variations depending on a
touch-doesn’t touch effect of the sheet are evident; such a situation is explainable if we suppose
that the man has his lower limbs bent.
The inflexion [1] would be due to the position taken on the cross and therefore to rigor
mortis; the assumption becomes probable if one thinks what the natural position of rest taken
 by a person lying down is. Moreover, such a position could also be the consequence of postmortal stiffening. The hypothesis is also supported by the non-flattening of some areas of the dorsal imprint, an effect that, because of gravity, should be present."
It's a bit late in the day to be talking about a "hypothesis". And I am beginning to suspect that this paper was not published in a journal, at least not in a recognized one. It looks to me more like a submission to a conference (as later confirmed -see earlier).  Peer review? 








Fig. 3.1:  Verbatim text, except for non-Greek characters:

Hypothetical position of the Man of the Shroud characterized by 4
parameters, the angles a, b, g, d, that respectively show the position of the head, the
femur, the tibia and the foot.


"Figure 3.2 shows that, just because of the inflexion of the lower limbs, the length of the leg
measured on the frontal side is longer than that measured on the dorsal side.
In fact bending a limb, the center of rotation being just next to the knee, one will have a
lengthening of the front leg and a shortening of the back one.
Analogous considerations must be made for the position of the feet.
The Man of the Shroud has his feet bent forward and this is very important for the
measurement; in fact as shown in Figure 3.3, the position of the heel changes considerably if
measured with a “hammer” or outstretched foot.
The heel itself being a fundamental reference point for the length of the tibia, it becomes
necessary to value this effect too."

  That's it. I have read enough.This paper is not about seeing if data fit a hypothesis. It is about using a computer to rejig data so as to make it  fit a preconceived idea (I decline to dignify the latter with the description "hypothesis"). 

This is not science. This is merely religious apologia masquerading as science.

It may be good enough to fool a particular science teacher cum internet-busybody, the one who held it up as "real science". But it does not fool this retired researcher science bod, one who actually reads and  evaluates papers first, instead of using them as weapons with which to browbeat total strangers on the internet...   :-(




1 comment:

Observer said...

How precise was the photographer in taking those pictures? If the front and rear were two separate photographs, was the camera exactly the same distance away from the image in both cases? And was it perpendicularly above the image in each case? In forensic work, there would be a right-angled ruler on the cloth. (These comments apply only to photographs of the cloth, not to measurements taken directly of the cloth itself.)