An object with an icon thereon encodes a bit sequence. The icon comprises a plurality of concentric rings, each of the plurality of concentric rings is divided into a plurality of data sectors. Each of the plurality of data sectors is associated with a corresponding bit in the bit sequence, and each of the plurality of data sectors encodes the corresponding bit based on the presence or absence of a line segment in the sector. The plurality of concentric rings further comprises at least three anchor sectors on one or more of the plurality of concentric rings, the at least three anchor sectors comprise an anchor mark. The plurality of concentric rings further comprises one or more error correction sectors, each of the one or more error correction sectors encodes a corresponding error correction bit based on the presence or absence of a line segment in the error correction sector.