A Cornsweet edge creates the perception of a step in surface lightness between two adjacent regions of identical mean luminance due to a gradient on both sides. We might imagine that in a concatenated set of these gradients. the lightness steps would accumulate. but they do not. https://www.jmannino.com/super-save-NFL-Chicago-Bears-Blast-iPhone-14-Plus-Skin-p41373-big-savings/