One of the progressive coding methods used in png images. Adam7, named after its author, Adam M. Costello, consists of seven distinct passes over the image. Each pass transmits a subset of the pixels in the image. The pass in which each pixel is transmitted is defined by replicating the following 8-by-8 pattern over the entire image, starting at the top left:

 1 6 4 6 2 6 4 6
 7 7 7 7 7 7 7 7
 5 6 5 6 5 6 5 6
 7 7 7 7 7 7 7 7
 3 6 4 6 3 6 4 6
 7 7 7 7 7 7 7 7
 5 6 5 6 5 6 5 6
 7 7 7 7 7 7 7 7