public distanceTo_00()

in src/canvastools/ts/CanvasTools/Core/Colors/LABColor.ts [79:142]

• 55 lines of code
• 12 McCabe index (conditional complexity)

    public distanceTo_00(color: LABColor): number {
        const [L1, a1, b1] = this.values;
        const [L2, a2, b2] = color.values;

        const kL = 1.0;
        const kC = 1.0;
        const kH = 1.0;
        const K1 = 0.045;
        const K2 = 0.015;

        const deg2rad = Math.PI / 180.0;
        const rad2deg = 180.0 / Math.PI;

        const deltaL = L2 - L1;
        const midL = (L1 + L2) / 2;
        const C1 = Math.sqrt(a1 * a1 + b1 * b1);
        const C2 = Math.sqrt(a2 * a2 + b2 * b2);
        const midC = (C1 + C2) / 2;
        const midC7 = midC ** 7;
        const midC7Root = Math.sqrt(midC7 / (midC7 + 25 ** 7));
        const a1t = a1 + 0.5 * a1 * (1 - midC7Root);
        const a2t = a2 + 0.5 * a2 * (1 - midC7Root);
        const C1t = Math.sqrt(a1t * a1t + b1 * b1);
        const C2t = Math.sqrt(a2t * a2t + b2 * b2);
        const midCt = (C1t + C2t) / 2;
        const deltaCt = C2t - C1t;
        const h1 = (b1 === 0 && a1t === 0) ? 0 : (Math.atan2(b1, a1t) * rad2deg) % 360;
        const h2 = (b2 === 0 && a2t === 0) ? 0 : (Math.atan2(b2, a2t) * rad2deg) % 360;

        let deltah = h2 - h1;
        const absDeltah = Math.abs(deltah);
        if (h2 <= h1 && absDeltah > 180) {
            deltah += 360;
        }
        if (h2 > h1 && absDeltah > 180) {
            deltah -= 360;
        }

        const deltaH = 2 * Math.sqrt(C1t * C2t) * Math.sin(0.5 * deltah * deg2rad);
        let H = (h1 + h2) / 2;
        if (absDeltah > 180 && h1 + h2 < 360) {
            H += 180;
        }
        if (absDeltah > 180 && h1 + h2 >= 360) {
            H -= 180;
        }

        const T = 1 - 0.17 * Math.cos((H - 30) * deg2rad)
                    + 0.24 * Math.cos((2 * H) * deg2rad)
                    + 0.32 * Math.cos((3 * H + 6) * deg2rad)
                    - 0.20 * Math.cos((4 * H - 63) * deg2rad);

        const SL = 1 + (K2 * (midL - 50)) / (Math.sqrt(20 + (midL - 50) * (midL - 50)));
        const SC = 1 + K1 * midCt;
        const SH = 1 + K2 * midCt * T;
        const RT = - 2 * midC7Root * Math.sin((60 * Math.exp(- ((H - 275) / 25) * ((H - 275) / 25))) * deg2rad);

        const diff = Math.sqrt((deltaL / (kL * SL)) ** 2
                             + (deltaCt / (kC * SC)) ** 2
                             + (deltaH / (kH * SH)) ** 2
                             + RT * (deltaCt / (kC * SC)) * (deltaH / (kH * SH)));

        return diff;
    }