This is a 15-patch grayscale step chart with 12 of the patches in a somewhat elliptical arrangement on the periphery and three in an inside row. Nominal patch densities are 0.1, 0.19, 0.3, 0.41, 0.53, 0.66, 0.81, 0.97, 1.17, 1.39, 1.66, 2.0 for the 12 peripheral patches and 0.77, 0.90, 1.05 for the three central patches. The relatively large patches are especially good for measuring noise.