This technology uses paper impregnated with billions of microscopic capsules of liquid photopolymer-based dye. The paper is exposed to light reflected from an original image, and the dyes inside the capsules harden in proportion to the amount of light they receive. The exposed paper is then pressed through steel rollers against a receiver paper, and varying amounts of unhardened dye are deposited on the receiver to form an image. The process can be used to make high-quality colour reproductions in small quantities but has few commercial applications.