Image from http://www.flickr.com/photos/chrisfreeland/5694222770/sizes/z/in/photostream/
Image from http://www.flickr.com/photos/kylemcdonald/5574420557/sizes/m/in/photostream/qr-code-marked-upbluer cyan are fiducials for tracking or quiet zones, can't be modified.yellow is format and version information that describe how big the code is and what the error correction level is.magenta is timing information (alternating black/white).the blocks of black/white pixels are data (cyan borders) and error correction (red borders).Reference: http://www.flickr.com/photos/kylemcdonald/5574420557/
Image from http://www.flickr.com/photos/cocreatr/2211459923/sizes/z/in/photostream/