Fig. 2
From: Ink marks, bronze crossbows and their implications for the Qin Terracotta Army
Example images of a trigger with a previously known ink mark from the southernmost corridor of the eastern trenches of Pit 1 in a visible (RGB) range (contrast-stretched), an ink Chinese character Jia (甲) can be clearly seen, b near infrared > 760 nm, and c near infrared > 950 nm