101 lines
2.3 KiB
JavaScript
101 lines
2.3 KiB
JavaScript
/**
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* CIE LUV (C'est la vie)
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*
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* @module color-space/luv
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*/
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import xyz from './xyz.js';
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var luv = {
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name: 'luv',
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//NOTE: luv has no rigidly defined limits
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//easyrgb fails to get proper coords
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//boronine states no rigid limits
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//colorMine refers this ones:
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min: [0, -134, -140],
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max: [100, 224, 122],
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channel: ['lightness', 'u', 'v'],
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alias: ['LUV', 'cieluv', 'cie1976'],
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xyz: function (arg, i, o) {
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var _u, _v, l, u, v, x, y, z, xn, yn, zn, un, vn;
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l = arg[0], u = arg[1], v = arg[2];
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if (l === 0) return [0, 0, 0];
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//get constants
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//var e = 0.008856451679035631; //(6/29)^3
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var k = 0.0011070564598794539; //(3/29)^3
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//get illuminant/observer
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i = i || 'D65';
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o = o || 2;
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xn = xyz.whitepoint[o][i][0];
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yn = xyz.whitepoint[o][i][1];
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zn = xyz.whitepoint[o][i][2];
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un = (4 * xn) / (xn + (15 * yn) + (3 * zn));
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vn = (9 * yn) / (xn + (15 * yn) + (3 * zn));
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// un = 0.19783000664283;
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// vn = 0.46831999493879;
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_u = u / (13 * l) + un || 0;
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_v = v / (13 * l) + vn || 0;
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y = l > 8 ? yn * Math.pow((l + 16) / 116, 3) : yn * l * k;
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//wikipedia method
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x = y * 9 * _u / (4 * _v) || 0;
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z = y * (12 - 3 * _u - 20 * _v) / (4 * _v) || 0;
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//boronine method
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//https://github.com/boronine/husl/blob/master/husl.coffee#L201
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// x = 0 - (9 * y * _u) / ((_u - 4) * _v - _u * _v);
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// z = (9 * y - (15 * _v * y) - (_v * x)) / (3 * _v);
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return [x, y, z];
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}
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};
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export default (luv);
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// http://www.brucelindbloom.com/index.html?Equations.html
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// https://github.com/boronine/husl/blob/master/husl.coffee
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//i - illuminant
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//o - observer
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xyz.luv = function (arg, i, o) {
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var _u, _v, l, u, v, x, y, z, xn, yn, zn, un, vn;
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//get constants
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var e = 0.008856451679035631; //(6/29)^3
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var k = 903.2962962962961; //(29/3)^3
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//get illuminant/observer coords
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i = i || 'D65';
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o = o || 2;
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xn = xyz.whitepoint[o][i][0];
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yn = xyz.whitepoint[o][i][1];
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zn = xyz.whitepoint[o][i][2];
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un = (4 * xn) / (xn + (15 * yn) + (3 * zn));
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vn = (9 * yn) / (xn + (15 * yn) + (3 * zn));
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x = arg[0], y = arg[1], z = arg[2];
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_u = (4 * x) / (x + (15 * y) + (3 * z)) || 0;
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_v = (9 * y) / (x + (15 * y) + (3 * z)) || 0;
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var yr = y / yn;
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l = yr <= e ? k * yr : 116 * Math.pow(yr, 1 / 3) - 16;
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u = 13 * l * (_u - un);
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v = 13 * l * (_v - vn);
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return [l, u, v];
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};
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