ATSI Bari, 5 September Paolo Di Lazzaro, Daniele Murra ENEA Center of Frascati

Transcription

1 ATSI Bari, 5 September 2014 Shroud-like coloration, conservation measures and image processing A survey of experiments at ENEA Frascati Paolo Di Lazzaro, Daniele Murra ENEA Center of Frascati paolodilazzaro@eneait paolo.dilazzaro@enea.it

2 Outline The images on the Shroud, STuRP Photochemistry-based linen coloration Conservation measures Misleading image processing Conclusion

3 The images on the Shroud Recent Photo of the Turin Shroud (Courtesy David Rolfe) The two faint body images have a lower contrast and are less visible than all the stains thereabouts: blood, water, burns.

4 The STuRP Project Torino, 8 14 October, scientists and technicians, 2.5 million $ equipment, 120 hours no stop analyses, 2 years for data elaboration

5 Main findings of STuRP The Shroud is not a painting, no pigment, any directionality, not a scorch. The image encodes cloth to body distance, and it is present in both contact and non contact areas. The image is superficial, no more than 0.6 microns thick (work by others has shown 0.2 microns). Invisible halos surround blood. Blood went on before image (no image beneath blood). The blood stains contain hemoglobin and serum albumin. Calcium and strontium and iron are uniformly present on the Shroud in small quantities.

6 STuRP conclusion We can conclude for now that the Shroud image is that of a real human form of a scourged, crucified man. Itisnottheproductofanartist. The blood stains are composed of hemoglobin and also give a positive test for serum albumin. The image is an ongoing mystery and until further chemical studies are made, perhapsbythisgroupof scientists, or perhaps by some scientists in the future, the problem remains unsolved.

7 Outline The images on the Shroud, STuRP Photochemistry-based linen coloration Conservation measures Misleading image processing Conclusion

8 Why photochemistry? Why UV? Energy carried id by short-wavelength h radiation i breaks chemical bonds of the irradiated material without inducing a significant heating (photochemical reaction). Moreover, linen has a molar absorptivity which increases when decreasing the radiation wavelength: the smaller the wavelength, the thinner the material necessary to absorb all the radiation. Then, we have chosen the ultraviolet l t radiation as an acting at distance mechanism to obtain at least two of the main characteristics of the Shroud image: a thin coloration depth and a low-temperature image-formation.

9 How much different is our linen from the Shroud? The solid lines show the absolute reflectance of the linen of the Shroud in areas of no-image as a function of the wavelength (Gilbert, Appl. Opt. 1980). Th d h d li h h b l fl f h li d i i The dashed line shows the absolute reflectance of the linen used in our experiments. From J. Imag. Sci. Techn. 54, 4302 (2010)

10 Set-up at ENEA Frascati Hercules ENEA PBUR 6 J, 120 ns, 5 Hz 308 nm LPX-305, PBUR 0.5 J, 30 ns, 50 Hz. 308 nm o 193 nm

11 Ultrashort UV pulses irradiate linens

12 Short movie Excimer laser irradiation of linen

13 Linen thread after 10ns, λ = 193nm irradiation From J. Imag. Science Techn. 54, (2010)

14 Depth of coloration: UV vs. VUV λ = 193 nm Cross section of irradiated linen threads λ = 308 nm Di Lazzaro, Regina Apostolorum 9/4/14

15 Sometimes VUV does not color the scw inside the fiber Note the small yellowish pieces of broken pcw From Applied Optics 51, 8567 (2012)

16 Latent images generated by VUV Unpublished

17 Half-tone effect by VUV irradiation Microscope view of linen threads after VUV laser irradiation. Single colored fibers are visible next to uncolored fibers, like in the Shroud image (areal density coloration). From Applied Optics 51, 8567 (2012)

18 Cold or thermal coloration? λ = 308 nm T = 21 C - 34 C λ = 193 nm T = 22 C - 25 C

19 Short movie The excimer laser as a contactless tl brush BS L EXCIMER LASER PD l OS

20 Shroud-like face using excimer laser as a brush The face image produced by laser shots is very faint, invisible at sunlight. Only in shadow we can perceive a low-contrast, yellowish faint image. Unpublished

21 Shroud-like face using excimer laser as a brush The negative of the previous photos shows a positive image. The negative allows to see the single laser shots producing the very faint image. Since 2013 it is exposed in the Museum of the Shroud in Turin Unpublished Di Lazzaro, Regina Apostolorum 9/4/14

22 Outline The images on the Shroud, STuRP Photochemistry-based linen coloration Conservation measures Misleading image processing Conclusion

23 From cellulose to cromophore (conjugated carbonyl groups) aldehyde CHO Alkene C=C and ketonic carbonyls C=O absorb λ < 320 nm (large bandwidth) absorb λ << 260 nm Aldehyde absorbs both 193nm and 308nm to generate cromophores. But only 193nm is absorbed by alkene and ketonic groups, thus delocalising groups and shifting absorption band to longer wavelengths, in the blue-green spectral region. This causes the yellow coloration. J. Appl. Polymer Science 16, (1972). Cellulose 1, (1994)

24 Ionizing radiation vs. Shroud conservation Gas Radon is the most dangerous source of natural ionizing radiation, potentially affecting the long term conservation of the image contrast and visibility. Our suggestions Gases and pressure Relative humidity, temperature 99.6% Ne or Ar, 0.4% O 2, RH 40% 9 mbar water vapor, T = 20 C P = 1,05 bar Box material / thickness Al or Al-based alloy t 5 mm Radon issue Building materials and objects around must be Radonfree Present reliquary 99.5% Ar, 0.5% O 2 RH = 50% Al alloy, Information not P equalized to the T = 19 C t variable available atmospheric pressure From EAI, special issue on Knowledge, Diagnostics and Preservation of Cultural Heritage, pp (2012).

25 Outline The images on the Shroud, STuRP Photochemistry-based linen coloration Conservation measures Misleading image processing Conclusion

26 A hidden face on the back of the Shroud? J. Opt. A: Pure Appl. Opt. vol. 6 pp (2004) Deep image processing of a screened photographic reproduction of the backside taken from a book. Image processing tools included d convolution lti with Gaussian filters, summation of images, gamma correction and filtering in spatial frequency by direct and inverse 2D Fourier transforms. Sindon vol. 19 pp (2003) Direct and inverse Fourier transform of a high- resolution image directly obtained by in-depth scanning of the backside of the Shroud, did not show any face or any other image.

27 A hidden face on the back of the Shroud? A direct, in depth analysis on the Shroud shows there is no hidden face or any other image on the backside of the Shroud. How can we crosscheck this result? ERCENTAGE PIXEL P We checked both images on the left have the same histogram of number of pixels vs. gray levels. Then, after the optimum spatial overlap of the two images (using bloodstains as a reference), the absolute value of the difference of gray levels between images should give a black figure when the two images are perfectly correlated, ora noisy figure when they have a partial degree of correlation, or a recognizable face when 1.2 their correlation is poor FRONT SIDE BACK SIDE GREY LEVEL

28 A hidden face on the back of the Shroud? A direct, in depth analysis on the Shroud shows there is no hidden face or any other image on the backside of the Shroud. How can we crosscheck this result? We checked both images on the left have the same histogram of number of pixels vs. gray levels. Then, after the optimum spatial overlap of the two images (using bloodstains as a reference), the absolute value of the difference of gray levels between images should give a black figure when the two images are perfectly correlated, ora noisy figure when they have a partial degree of correlation, or a recognizable face when their correlation is poor. The result of this pixel-by-pixel calculation is shown on the left, where a Shroud-like face can be still recognized, thus revealing the lack of spatial correlation of the images above, as a whole. From Pattern Recognition 46, 1964 (2013)

29 No hidden face on the back of the Shroud The lack of spatial correlation between the hidden face backside and the face on the Shroud is further confirmed by atemplate matching based on a cross-correlation algorithm that calculates the Pearson product-moment correlation coefficient S according to the following equation: = where Aij (Bij) is the gray level of the single pixel (i,j) (ij) of the image A (B), and <A> (<B>) is the mean value of the gray level of the image A (B). When applying this equation to the front and hidden face on the back we obtain S = 0.4 S = 0.4 is a very poor spatial correlation value, typical of completely different images. As an example, Figures on the left have the same correlation coefficient S = 0.4 of the front and presumed back faces on the Shroud

30 Why we perceive a face on the back of the Shroud? In summary, both a direct, in-depth analysis on the Shroud and two different methods of spatial correlation show there is no hidden face on the backside of the Shroud. It remains the problem to understand why most of us can perceive a Shroud-like face on the back, if it does not exist. The presumed face on the back actually contains 3 faces at least The face-like patterns we perceive is possibly due to a combined effect of the brain s ability to supply the missing contours in order to make sense out of any pattern we can see and of our innate propensity p to interpret stimuli as faces based on minimal cues. As a matter of fact, we are hard-wired to perceive faces from several random patterns!

31 Our psychophysiology mechanism sees faces everywhere

32 How it works? Retrieving capability of our brain Can you read me? Can you read me? When a phrase is in a context, our brain is able to retrieve its meaning even when it is hlf half cancelled (Gestalt: t perception isnot a simple addition of the elements we see, but it is the result of the relations among the observed objects). A single letter, when half cancelled, cannot be retrieved (detail vs. context). C4N Y0U R34D M3? The same ability of retrieving incomplete information holds for looking like patterns (numbers instead of letters).

33 Outline The images on the Shroud, STuRP Photochemistry-based linen coloration Conservation measures Misleading image processing Conclusion

34 Conclusion We have presented the first comprehensive survey of the overall research work on Shroud-related issues done in the last 8 years in the ENEA Research Center of Frascati. Our irradiations of linen fabrics show the ability of ultra-short, high intensity UV and VUV radiation to reproduce many peculiar aspects of the microscopic complexity of the Turin Shroud images. The different coloration results obtained in different irradiation conditions allow to recognize photochemical reactions involved in our Shroud-like coloration, thus offering hints to plan the long-term conservation of both cloth and image of the TS. Our study of the misleading effects of digital image processing of low-contrast t images confirms thatt there is a narrow boundary between image enhancement and manipulation. Our results corroborates previous works showing the absence of any face on the backside of the Shroud.

35 Contributions from Giuseppe Baldacchini Paolo Di Lazzaro ENEA Frascati ENEA Frascati Giulio Fanti Pd Padua University it Daniele Murra Enrico Nichelatti Antonino Santoni Barrie Schwortz ENEA Frascati ENEA Casaccia ENEA Frascati STERA Inc. who gave a contribution to different phases of this long-term work and coauthored papers published in peer reviewed journals

36 Deeper insights may be found in G. Baldacchini, P. Di Lazzaro, D. Murra, G. Fanti: Coloring linens with excimer lasers to simulate the body image of the Turin Shroud Applied Optics 47, (Optical Society of America, 2008). P. Di Lazzaro, D. Murra, A. Santoni, G. Fanti, E. Nichelatti, G. Baldacchini: Deep Ultraviolet radiation simulates the Turin Shroud image Journal of Imaging Science and Technology 54, (6) (Imaging.org 2010). D. Murra, P. Di Lazzaro: Sightg and brain, an introduction to the visually misleading images, International Workshop on the Scientific approach to the Acheiropoietos Images, edited by P. Di Lazzaro (ENEA 2010) pp P. Di Lazzaro, D. Murra, A. Santoni, E. Nichelatti, G. Baldacchini: Superficial and Shroud-like coloration of linen by short laser pulses in the vacuum ultraviolet Applied Optics 51, (Optical Society of America, 2012). P. Di Lazzaro, D. Murra, B. Schwortz: Pattern recognition after image processing of low-contrast images, the case of the Shroud of Turin Pattern Recognition 46, (Elsevier, 2013).