Three Dimensional Data Storage

One aspect of the invention comprises a method of embedding data in a code readable by machine from a visible light scan of the code. The method comprises pre-printing a two dimensional array of pixels on a substrate. The pixels include at least one calibration pixel, and each have color values. The method selectively alters at least a subset of the pixels by using laser radiation to alter color saturation of the color values of the pixels in the subset relative to the calibration pixel according to digital data values of the code to be embedded in the subset of pixels. This method has been adapted to embed personalized information in pre-printed graphic elements on ID cards.