Ink Tone Analysis of Printed Character Images towards Identification of Medieval Korean Printing Technique: The Song of Enlightenment (1239), the Jikji (1377), and the Gutenberg Bible (~1455)

To identify printing techniques for medieval Korean books, ink tone analysis of printed characters is proposed. Ink tones character images in two ancient The Song Enlightenment with Commentaries by Buddhist Monk Nammyeong Cheon (南明泉和尙頌證道歌), designated as treasures 1984 and 2012, were compared analyzed. Both books have been misidentified disclosed the Cultural Heritage Administration Korea woodblock-printed versions from Goryeo dynasty 13th century. showed clear differences brightness histograms between on suggesting technique differences. Statistical revealed totally different (or darkness) pixels, within inked areas, materials used books. was performed Jikji (直指: metal type 1337) Gutenberg Bible (metal Europe around 1455) comparisons. As additional references, conducted sets old titled Myeongeuirok (明義錄), 1777, Sok-Myeongeuirok (續明義錄), 1778, using both re-carved woodblocks. Gongin version Enlightenment, a treasure very similar distribution average metal-type-printed 14th to 18th centuries. All spotty prints lighter more symmetrical can provide insights into identification method. It evidence (空印本) 2012. interest world’s oldest extant book, September 1239, indicated imprint. This predates (1377) 138 years 42-line (~1455) 216 years.