Binary matrices of optimal autocorrelations as alignment marks
  We define a new class of binary matrices by maximizing the peak-sidelobe distances in the aperiodic autocorrelations. These matrices can be used as robust position marks for in-plane spatial alignment. The optimal square matrices of dimensions up to 7 by 7 and optimal diagonally-symmetric matrices of 8 by 8 and 9 by 9 were found by exhaustive searches. 
Scott A. Skirlo, Ling Lu and Marin Solja\v{c}i\'c
cs.CV cs.IT math.IT