paint off, pixel ratio 2: band error (L*), the shipped dither measured vs predicted from the curve alone
glow        measured 0.076 (mean +0.051)   predicted 0.079 (mean +0.053)
faint       measured 0.087 (mean +0.064)   predicted 0.091 (mean +0.066)
stack       measured 0.074 (mean +0.051)   predicted 0.057 (mean +0.034)
concentric  measured 0.111 (mean +0.075)   predicted 0.066 (mean +0.040)
ring        measured 0.049 (mean +0.029)   predicted 0.048 (mean +0.029)