[TXnMA]

Closest analogue imaging process that comes to mind is "Dye Sublimation" Printing, wherein the dye is vaporized from one surface by intense, localized, patterned heat -- and the resulting dye vapor condenses only on the surface of the material being printed.

Makes sense to me...

[BerryDingle]

I remember talking to an older man in S. Korea who was a former slave in Japan when one of the atomic bombs was dropped. He had his back towards ground zero during the brilliant flash of light and heat. The pattern of a denim shirt he had on was “tatooed” into his back. He raised his shirt up and showed me.

[kik5150]

The image is not created from a dye or pigment. The film of soapwort on the surface of the linen has been caramelized in a dot-matrix pattern to form the image. Heat alone could not cause this as there is no evidence of scorching in the fibers of the cloth.