US Patent 7191336 Method for embedding information in an image

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×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×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.