Alpha compositing playground

The entire "remove / change background" trick is this one line, run for every pixel: new = α·person + (1−α)·background. Drag the sliders — the math computes live. From the post How an AI cuts you out of a photo.

α — how much of this pixel is "person" (what the AI's matte says): 0.62 person pixel color (hair, skin…) new background color (beach sky, passport white…)

person

×α +

background

×(1−α) =

the pixel you see

α=1 → pure person (faces never get touched). α=0 → pure background. The soft grays at hair edges are everything in between.

…and here it is running on a whole edge. Drag α to re-composite a hair-edge strip against the background color above:

Left: fully "person". Right: fully background. The anti-aliased middle is where the equation earns its keep.

Everything on this page runs in your browser — like every JigsawLabs tool, including Remove Background itself. 🔒 Nothing uploads.