rgbdiff.js

define("rgbdiff", [], function () {
    function rgbdiff(a, b) {
        // Convert RGB to XYZ

        function rgbToXyz(tuple) {
            var _r = (tuple[0] / 255);
            var _g = (tuple[1] / 255);
            var _b = (tuple[2] / 255);
            if (_r > 0.04045) {
                _r = Math.pow(((_r + 0.055) / 1.055), 2.4);
            } else {
                _r = _r / 12.92;
            }
            if (_g > 0.04045) {
                _g = Math.pow(((_g + 0.055) / 1.055), 2.4);
            } else {
                _g = _g / 12.92;
            }
            if (_b > 0.04045) {
                _b = Math.pow(((_b + 0.055) / 1.055), 2.4);
            } else {
                _b = _b / 12.92;
            }
            _r = _r * 100;
            _g = _g * 100;
            _b = _b * 100;
            X = _r * 0.4124 + _g * 0.3576 + _b * 0.1805;
            Y = _r * 0.2126 + _g * 0.7152 + _b * 0.0722;
            Z = _r * 0.0193 + _g * 0.1192 + _b * 0.9505;
            return [X, Y, Z];
        };
        // Convert XYZ to LAB

        function xyzToLab(tuple) {
            var ref_X = 95.047;
            var ref_Y = 100.000;
            var ref_Z = 108.883;
            var _X = tuple[0] / ref_X;
            var _Y = tuple[1] / ref_Y;
            var _Z = tuple[2] / ref_Z;
            if (_X > 0.008856) {
                _X = Math.pow(_X, (1 / 3));
            } else {
                _X = (7.787 * _X) + (16 / 116);
            }
            if (_Y > 0.008856) {
                _Y = Math.pow(_Y, (1 / 3));
            } else {
                _Y = (7.787 * _Y) + (16 / 116);
            }
            if (_Z > 0.008856) {
                _Z = Math.pow(_Z, (1 / 3));
            } else {
                _Z = (7.787 * _Z) + (16 / 116);
            }
            var CIE_L = (116 * _Y) - 16;
            var CIE_a = 500 * (_X - _Y);
            var CIE_b = 200 * (_Y - _Z);
            return [CIE_L, CIE_a, CIE_b];
        };
        // Finally, use cie1994 to get delta-e using LAB

        function cie1994(x, y, isTextiles) {
            var x = {
                l: x[0],
                a: x[1],
                b: x[2]
            };
            var y = {
                l: y[0],
                a: y[1],
                b: y[2]
            };
            var k2;
            var k1;
            var kl;
            var kh = 1;
            var kc = 1;
            if (isTextiles) {
                k2 = 0.014;
                k1 = 0.048;
                kl = 2;
            } else {
                k2 = 0.015;
                k1 = 0.045;
                kl = 1;
            }
            var c1 = Math.sqrt(x.a * x.a + x.b * x.b);
            var c2 = Math.sqrt(y.a * y.a + y.b * y.b);
            var sh = 1 + k2 * c1;
            var sc = 1 + k1 * c1;
            var sl = 1;
            var da = x.a - y.a;
            var db = x.b - y.b;
            var dc = c1 - c2;
            var dl = x.l - y.l;
            var dh = Math.sqrt(da * da + db * db - dc * dc);
            return Math.pow(Math.pow((dl / (kl * sl)), 2) + Math.pow((dc / (kc * sc)), 2) + Math.pow((dh / (kh * sh)), 2), 2);
        };
        return cie1994(xyzToLab(rgbToXyz(a)), xyzToLab(rgbToXyz(b)))
    }

    function srgbdiff(a, b) {
        var ref_X, ref_Y, ref_Z, ref_U, ref_V, lab_e, lab_k;
        ref_X = 0.95047;
        ref_Y = 1.00000;
        ref_Z = 1.08883;
        ref_U = (4 * ref_X) / (ref_X + (15 * ref_Y) + (3 * ref_Z));
        ref_V = (9 * ref_Y) / (ref_X + (15 * ref_Y) + (3 * ref_Z));
        lab_e = 0.008856;
        lab_k = 903.3;

        function f(t) {
            if (t > lab_e) {
                return Math.pow(t, 1 / 3);
            } else {
                return 7.787 * t + 16 / 116;
            }
        };
        dot_product = function (a, b) {
            var i, ret, _i, _ref;
            ret = 0;
            for (i = _i = 0, _ref = a.length - 1; 0 <= _ref ? _i <= _ref : _i >= _ref; i = 0 <= _ref ? ++_i : --_i) {
                ret += a[i] * b[i];
            }
            return ret;
        };

        function srgb2xyz(tuple) {
            var m, rgbl, to_linear, _B, _G, _R, _X, _Y, _Z;
            _R = tuple[0], _G = tuple[1], _B = tuple[2];
            to_linear = function (c) {
                var a;
                a = 0.055;
                if (c > 0.04045) {
                    return Math.pow((c + a) / (1 + a), 2.4);
                } else {
                    return c / 12.92;
                }
            };
            m = [
                [0.4124, 0.3576, 0.1805],
                [0.2126, 0.7152, 0.0722],
                [0.0193, 0.1192, 0.9505]
            ];
            rgbl = [to_linear(_R), to_linear(_G), to_linear(_B)];
            _X = dot_product(m[0], rgbl);
            _Y = dot_product(m[1], rgbl);
            _Z = dot_product(m[2], rgbl);
            return [_X, _Y, _Z];
        }

        function xyz2lab(tuple) {
            var fx, fy, fz, _L, _X, _Y, _Z, _a, _b;
            _X = tuple[0], _Y = tuple[1], _Z = tuple[2];
            fx = f(_X / ref_X);
            fy = f(_Y / ref_Y);
            fz = f(_Z / ref_Z);
            _L = 116 * fy - 16;
            _a = 500 * (fx - fy);
            _b = 200 * (fy - fz);
            return [_L, _a, _b];
        }

        function srgb2lab(tuple) {
            return xyz2lab(srgb2xyz(tuple));
        }
        var alab, blab;
        alab = srgb2lab(a);
        blab = srgb2lab(b);
        return Math.sqrt(Math.pow((alab[0] - blab[0]), 2) + Math.pow(alab[1] - blab[1], 2) + Math.pow(alab[2] - blab[2], 2));
    }
    return rgbdiff;
});