How hidden manuscript text reappears

Transcript

Scientists photograph the manuscript in many wavelengths, from ultraviolet through infrared, because different inks and parchment react differently to each band. They then process the raw images with tools such as principal component analysis, independent component analysis, or specialized software to make the hidden writing stand out. When parchment is coated with calcium or the text sits too deep, X-ray fluorescence can separate the ink from the surface chemistry without touching the book. For sealed books, computed tomography can even build a 3-D volume and virtually flatten the pages, so the text can be read without opening the binding.