Tikalon Blog by Dev Gualtieri

Reading Old Manuscripts

May 15, 2023

Stone was used as a medium for permanent writing in Egypt as early as its Naqada II (Gerzeh) period, 3500 – 3200 BC. The permanance of this writing medium is evidence by fragments that are readable after more than 5,000 years. Similar permanence was achieved by scribing cuneiform into clay tablets at around the same Bronze Age period.

Stone and clay offer permanance of writing, but their texts are not that portable. Papyrus, introduced at about the same time during the First Dynasty of Egypt, was a more portable medium. The permanance of papyrus texts was assured through the use of permanent inks with carbon black and ochre pigments. The carbon black was obtained from soot, and the ochre achieved its red pigmentation through ferric oxide (Fe₂O₃) that's also present in the mineral, hematite.

Some ancient texts - Rosetta Stone, Book of the Dead papyrus, and a cuneiform clay tablet.

Three very ancient texts. Left, a portion of the Rosetta Stone, 196 BC. Center, a portion of the Book of the Dead papyrus, circa 1050 BC. Right, a clay tablet with cuneiform writing, circa 1525 BC. (Left, a Wikimedia Commons image by Nolde16. Center, a portion of a Wikimedia Commons image from the Rogers Fund, 1930, of the Metropolitan Museum of Art. Right, a Wikimedia Commons image by Gary Todd. Click for larger image.)

Parchment for writing appeared about a millennium after papyrus. In the 5th century BC, Herodotus (c.484-c.425 BC) writes in his Histories that parchment was common in his time and had been in use for hundreds of years as a substitute for papyrus when it was unavailable. Pliny the Elder (c.23-79 AD), in his Naturalis historia (Natural History) writes that public documents were inscribed on sheets of lead, and private documents were written on linen cloth or engraved on wax tablets.[1] Homer's Iliad alludes that tablets, presumably made from wax, were used before the time of the Trojan War.[2]

Pliny erroneously posits a date more recent to his time for the use of parchment at the Library of Pergamum; viz.,

"Ptolemy prohibited the export of papyrus; upon which, as Varro relates, parchment was invented for a similar purpose at Pergamus. After this, the use of that commodity, by which immortality is ensured to man, became universally known."[1]

Today's print medium is paper. The papermaking process was invented in China at around the 1st century. Paper started to replace papyrus around the 8th century, and papermaking reached Europe in the 11th century where it replaced parchment. Paper was being produced on an industrial scale in the 13th century, and in the 19th century, wood replaced other fibers, such as cotton, in papermaking.

Wood-based paper was inexpensive; and, as a corollary to Gresham's law, since print on wood-based paper appeared nearly identical to that on higher quality papers, everything became printed on wood-based paper. Wood pulp contains lignin, which turns yellow, brittle, and deteriorates over time. Acids used in the pulping process accelerate this ageing. As a consequence, library collections were crumbling by the early twentieth century, and papermaking was modified to improve paper quality.

Today, acid-free paper is produced without lignin or sulfur, and the acids in the wood pulp are neutralized with a mild base, such as calcium bicarbonate or magnesium bicarbonate. A slight excess of bicarbonate provides a reserve against environmental attack from air pollution, and such alkaline papers have a lifetime of five hundred to more than a thousand years.

The three common chemical components, called monolignols, of lignin, and the symbol for acid-free paper.

Left, the three common chemical components, called monolignols, of lignin , and the symbol for Permanent Paper.

Top, paracoumaryl alcohol, center, coniferyl alcohol, and, bottom, sinapyl alcohol.

The unicode for the Permanent Paper Sign in unicode is U+267E.

(Left images (modified) by Yikrazuul, and right image, both from Wikimedia Commons. Click for larger image.)

While the demise of paper, as in the paperless office, has been predicted for many decades, paper use only started to significantly decline in the last decade. The migration of information to digital data has its problems. While documents from thousands of years ago can still be read, it's unlikely that today's digital data could be read just a century from now. Our cultural heritage (including these blog articles?) could be lost to posterity.

Old documents are in various states of readability, and many scientific techniques have been used to enhance their contents. These include fluorescence microscopy, infrared microscopy, X-ray analysis, and computer image restoration techniques. Common problems are fading, and bleed-through from the obverse of a page. A recent open access paper in PLOS, the Public Library of Science, presents a document restoration method for color manuscripts.[3] Research team members are from the GIK Institute, (Topi, Pakistan), the Istituto di Scienza e Tecnologie dell'Informazione Alessandro Faedo (Pisa, Italy), the University of Birmingham (Birmingham, United Kingdom), iFahja Limited (United Kingdom), and the National University of Computer and Emerging Sciences (Islamabad, Pakistan).[3]

One important aspect of this document restoration method is that artificial intelligence is not involved; so, you can actually understand how the results are obtained. The method uses the information obtained from each color channel at each pixel, which could be the conventional red, green, and blue (RGB), or these plus additional data from infrared, etc., as available. These data form a feature vector. The method involves reducing the size of the image dataset by principal component analysis and using a Gaussian mixture model for the analysis. As they say, an interested reader is referred to the original paper, in which the relevant equations are given.[3]

More interesting than any of the mathematics are examples of this method. As shown in the following figures, the approach works well for bleed-through removal and enhancement of degraded images.

An example of bleed-through removal.

Top, manuscript with bleed-through from the obverse of the page. Bottom, the restored image using the method of the PLOS paper.

Portion of fig. 2 of ref. 3, released under a Creative Commons Attribution License.

Restoration of a degraded manuscript. Left, the original manuscript. Right, a restored image using the method of the PLOS paper. (Portion of fig. 3 of ref. 3, released under a Creative Commons Attribution License. Click for larger image.)

Reading Old Manuscripts

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