visible and ultraviolet illumination Wall Paintings at Mogao Grottoes
 

A text cartouche shown under visible and ultraviolet illumination. The Chinese characters on the cartouche, difficult to read in visible light, becomes clearly legible under UV illumination. This technique has enabled the study, recording and transcription of cartouches by Dunhuang Academy scholars. Credit: Francesca Piqué and Lori Wong.