The problem with those codes, along with things like RFID and NFC tags, is that they detract from the appearance of the item. Fujitsu Laboratories, however, has developed an alternative system. It uses the light shining on the object to convey data.
The system incorporates existing RGB LED lights, which are able to emit red, green or blue light (or any mixture thereof) from a single bulb.
Ordinarily, such bulbs are kept at a single color setting, which can even just be a neutral white-ish color. In Fujitsu's system, though, the light rapidly fluctuates between emitting red- and blue-tinted light – the red pulses represent 0's in binary code, and the blue ones represent 1's.
The fluctuations are so rapid, and the tints are so subtle, that the human eye simply sees the bulb's output as continuous white lighting. A mobile device running the proper software, however, is able to detect the code in the light reflected off the displayed item – it's even able to compensate for the fact that some of the light is absorbed by the surface of the object.