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Showing posts with label Leonardo da Vinci. Show all posts
Showing posts with label Leonardo da Vinci. Show all posts

Thursday, July 22, 2010

Science, Art & Deception of the Mind

In his investigative report with the title "The mark of a masterpiece" published July 12, 2010, in The New Yorker, David Grann informs us about the novel use of methods adopted from forensic science to authenticate works of art. Deception seems intricately interwoven with art. Grann's fascinating story informs us about the scientific method and the power of deceit. It tells us about people who become vulnerable to deception and exploitation on their quest for affirmation of their believe because of pride, ego and money. Establishing the provenance of a masterpiece mainly relies on the subjective expertise to date. However, the desire to discover a new masterpiece by a fabled artist may obfuscate judgment and reason. Definitive objective prove is, therefore, highly sought after.

David Grann portrays the art expert Peter Paul Biro. Biro gained distinction in the world of art for using cutting-edge scientific methods to successfully identify fingerprints of famed masters like Turner, Pollock and Leonardo on hitherto-unknown paintings and drawings. He employs spectral microscopy and computer-supported image analysis to derive his conclusions.

We tend to believe that we are able to establish veracity beyond any doubt with hard data produced by objective machines that do not posses vested interests in the outcome of the examination. However, as David Grann's investigation elegantly reveals, the interpretation of the data may entirely lie in the hands of the investigator. He takes sole responsibility of deciding whether the evidence is sufficient to prove the identity of the fingerprint in question.

Because of our fallibility, more than one expert commonly shoulder such decisions. Peter Paul Biro states that he developed his own imaging equipment, which is one of a kind. No other expert could be asked to verify his findings because they lack the experience with the revolutionary methods he devised. The burden of prove rests with him alone.

This situation puts Biro in a unique position of extraordinary responsibility. The scientific method insists on the reproducibility of findings, preferably by independent examination. Additional verification with different methods may be necessary. Peter Paul Biro is intending to use DNA profiles from hair samples for this purpose. As the only expert in his method, he must know that his career and future depend on his truthfulness. Any scientist's credibility is intimately linked to her/his integrity. Deliberate misrepresentation of evidence is a serious offense, destroying the most highly-respected reputation.


Addenda
  • Anyone versed in fluorescence or confocal microscopy could quickly learn how to image fingerprints. You may not even need a microscope. The detective in the video uses a magnifying glass to examine them. A CCD camera with a macrolense on a solid stand will suffice. A a high-quality light source and fiber optics are needed to produce sufficient illumination of the specimen as well as light filters for the wavelengths at which the images need to be captured. For storage and processing we need a computer with frame grabber and software.  In total, the equipment may not cost more than $100,000.-. The software for the described image treatment, that is background correction and subtraction, contrast enhancement and erosion to lay bare patterns, alignment and overlay of images as well as subsequent differentiation can be achieved with Wayne Rasband's ImageJ. The application is java-based freeware and can be downloaded from Wayne's National Institutes of Health site. The site also provides helpful information on equipment. For statistical analysis, we could quantify the number of picture elements, also known as pixels, in which the compared fingerprints overlap and use pixel-by-pixel paired t-tests to assess statistical significance as measures of identity. According to Grann, Biro charges $1,000.- per day for his qualitative analyses of fingerprints. His judgment must account for most of the cost (07/22/10).
  • Bryony Jones reports in her post with the title "Museum discovers 'new' painting" published online by CNN on Mar. 23, 2012, on an excellent example demonstrating how improved X-ray spectrography helped authenticate a Van Gogh painting previously attributed to an imitator. The painting depicts a still-life of summer flowers exhibited in the Kröller-Müller Museum in Otterlo, the Netherlands. It had been examined with less powerful X-ray methods before, and it was known that there was another composition underneath. Using the new imaging method, experts unambiguously uncovered under the still-life two wrestlers entangled in a match known to have been painted by the famous painter. In addition, the method confirmed that the pigments in the paints were consistent with those used by Van Gogh at the time. Modern technology correctly applied helps (03/24/2012).
  • On rare occasions, identification seems straight-forward. The proud new owner of this Renoir rediscovered comments: “One man's trash is another (wo)man's treasure!” (09/12/2012):
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Monday, December 3, 2007

Leonardo's View

I just was reminded of the great Leonardo da Vinci the other day. A book entitled “La Musica Celata” has just been published in which the author, Giovanni Maria Pala, lays out evidence that a musical theme is embedded in Leonardo's painting of the Last Supper. That Leonardo was truly one of a kind! His drawings and paintings reflect such a keen sense of actuality and maybe more. I am a neuro-anatomist by training. I always admired realistic drawings of the human body. In my mind, Leonardo was the first modern anatomist.

I once could visit a traveling exhibit of his drawings and notes on human anatomy at the Philadelphia College of Physicians. Beside the very impressively detailed renderings of muscles and bones, drawings on the brain caught my eye. On one parchment (Fig. 5), a schema on how the brain may work was center stage. The ventricles, that is the fluid-filled cavities, were of utmost importance. In Leonardo's time, it was commonly accepted that our thoughts, our spirit, would travel with the juice in the ventricles. The nerve cells were discovered only centuries later. However, the Maestro was not going to be fooled. If you train your eye on the lower left corner of the parchment, you discover that what looks like a smudge is the faint impression of a more detailed drawing of brain structure. As if Leonardo tried to draw something as he saw it and then erased it. The other parchment (Fig. 6) shows his method of reproducing the shape of the ventricles by filling them with wax in the bovine brain. On this parchment, again the ventricles take center stage, Yet, on the right side there is another faint drawing. This time, the shape is distinct. You see a very realistic reproduction of the cerebral cortex with its sulci and gyri. Though it may seem human, it is most likely the cortex cerebri of a cow. Yes, also ruminants have a cortex with numerous convolutions. That must have caught the Maestro's eye. I can imagine that he mumbled to himself: ”Only shows the limits of inductive thinking. This proves that cortical convolutions are no key to intellect!” And all the world's cows must have agreed with a resounding:” Moo!”

If you like to see more of Leonardo's notes on human anatomy, check in a book like Leonardo Da Vinci on the Human Body. In his studies, Leonardo was constantly struggling with the unreal views of the day and with the actuality that he saw and could not help, but draw. He must have erased his impression of reality many times, because of his fear of the authorities. Dissecting bodies was forbidden. He wrote his notes on the parchments in mirror image to conceal his thoughts from the average person who may have betrayed him. But, then he could not efface his convictions entirely. In the end, Leonardo's perceptions of the brain were correct, and he stands tall today. What can we learn from this?

Trust your own eyes more than anything, particularly when the views of the day get in the way.


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