Abstract: A dye donor, such as a transfer ribbon, comprises a supporting substrate and a relatively thick dye layer consisting of a dye dispersed within a dye binder. A heater, such as a modulated scanning laser beam, heats selected pixel regions of the ribbon and causes dye to diffuse from the heated regions to a receiver sheet and print a number of pixels thereon which build up to form an image. In order to allow the donor to be reused, it is passed between a pair of heated rollers to cause dye in the dye layer to diffuse to an even density whereby the regions depleted of dye during the print process are replenished. Instead of the replenishment dye coming from the body of the donor, it may be supplied by a separate source.