A method for encoding data in a monochrome media utilizing the capability of the media for grayscale resolution. A document is processed to provide an image in electronic format, in which each pixel has an assigned data value with a given bit depth. A mapping operation is performed for generating a monochrome data word (120), preferably having a reduced bit depth. The monochrome data word (120) can be used to encode multiple data fields (114, 116, 118). A printer (92) then produces a preserved document record (90) in which the appropriate monochrome data word (120) determines the grayscale value for each pixel.