Variable sharpen`Const`

sharpen: MultipassFilter<
    {
        amount: {
            default: 0.5;
            description: "Strength of the sharpening; 0 changes nothing.";
            label: "Amount";
            max: 3;
            min: 0;
            step: 0.01;
            type: "float";
        };
    },
> = ...

3×3 Laplacian sharpen on colour: c' = c + amount · (4c − N − S − E − W). Alpha is kept and colour is floored at 0 (overshoot below black is not light). Values above 1 are allowed.