Multiply blend mode darkens by multiplying per-channel values, giving white transparency and black full darkening

Multiply: f(a,b) = ab. Since both a and b are in [0,1], the result is always ≤ either input — the composite is always darker or equal. Where either layer is white (value 1.0), the result equals the other layer (identity). Where either layer is black (0.0), the result is black. The mode is commutative: swapping layers gives the same result. If both layers contain the same image, the result is equivalent to gamma correction with γ=2 (squaring the values). Practical use: multiply a coloured layer over a white background to preserve the background structure while applying a tint; multiply two shadow layers to deepen shadows without affecting lights.

Examples

Multiply a red layer (r=1,g=0,b=0) over a grey (0.5,0.5,0.5): result (0.5,0,0) — dark red. Multiply white over anything: no change. Multiply black over anything: black.

Assessment

Given two layers with values a=0.8 and b=0.6, compute the Multiply result. Then explain why Multiply is useful for darkening without clipping highlights to pure black.