Divide blend mode divides the base by the top layer, so a darker top brightens the base and any colour over black becomes white

Divide divides the RGB channel values of the bottom (base) layer by those of the top layer. The darker the top layer, the brighter the base appears (dividing by a small number grows the result). Blending any colour with black yields white (division by ~0 blows up to the clip ceiling); blending with white has no effect (division by 1). It is not invertible because highlights can clip. Blended with a homogeneous colour it uniformly raises contrast, especially in highlights, and can be used to remove a uniform colour tint by dividing by the tint itself — a white-point correction.

Examples

Divide a photo by a mid-grey (0.5): every channel doubles, brightening highlights. Divide by the exact colour of an unwanted tint to neutralise it (white-balance style correction). Divide anything by white: unchanged.

Assessment

Predict Divide’s output when the top layer is (a) black, (b) white, (c) mid-grey, and explain how Divide can correct a uniform colour cast in a photo.