Method of decoding data encoded in a monochrome medium

A method for decoding data that has been encoded in a monochrome medium utilizing the capability of the medium 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. To decode the stored data, a scanner ( 86 ) is employed to obtain the grayscale value from the preserved document record ( 90 ). For each pixel, the grayscale value is then decomposed into multiple data fields ( 114, 116, 118 ), which can then be decoded to provide the information that was originally encoded.