Tiles are rotated so that they form a diagonal checkerboard pattern. This was done to eliminate any bias toward white or black.

A tile owned by black that has no black neighbors is decorated with a dark grey mask (see near the top, to the right of under the trash can).

A tile owned by white that has no white neighbors is decorated with a light grey mask (see the three squares just to the left and below the center of the board).

For the rest of the tiles, there is a green mask added. The intensity of the green is related to the number of neighbors of the same color mutually connected. For this rotation, the maximum number of mutual neighbors is 4, if all 4 tiles occupying a checkerboard diamond have the same color stones.

Note also that the white stones sit on the white side of the tiles and the black stones sit on the black side. There is only one stone per tile.