A method for producing a background image representing data. The
background image is created by; producing a first encoding of data into a
first binary array; producing a second encoding of the data into a second
binary array; representing the first binary array as a first set of
modules of a first size of n.times.n pixels wherein each pixel is either
white or black and every pixel in the module is identical to every other
picture in the module on nodes of a first lattice, representing the
second binary array as a first set of modules of a second size, of
m.times.m wherein each pixel is either white or black and every pixel in
the module is identical to every other pixel in the module, which is
smaller than the first size on nodes of a second lattice, combining the
first and second sets of modules; and printing the first and second sets
of modules.