Information bearing devices can be useful sources of information. An information bearing device may comprise human perceivable signs and/or human non-perceivable signs. Road signs, pictures of animals, national flags, words, alphanumeric characters, non-alphanumeric characters such as Asian or Arabic characters, are example of human perceivable signs. Barcodes, QR codes, scrambled codes, watermarks, and transform domain images are example of non-human perceivable signs.

The human culture is substantially founded on human readable signs, and human readable signs are primarily built of human readable symbols such as alphanumerical characters, non-alphanumerical characters, Latin or non-Latin characters, Asian characters, Greek, Arabic or Egyptian symbols, in ASCII, Unicode or otherwise, or a combination thereof.

While human readable signs provide useful information to the human reader, there are occasions where information is stored in information bearing devices comprising human non-perceivable signs. The use of human non-perceivable signs in information bearing devices may be to hide information from human readers, to facilitate machine reading of information, or a combination of both. For example, manufacturer's information or costing information of products may be hidden from the public by embedding them in a machine coded pattern alongside human perceivable information such as price, materials, products identification information, size, etc. on a tag attached to a product.

As image capturing devices capable of capturing digital images of a high image resolution are readily available due to the increasing popularity of smart phones, human non-perceivable signs in the form of machine coded images are increasingly useful for combating counterfeiting.

