RGB to LAB

rgbToLab.js

function rgbToLab( R, G, B ) {
    R = ( R / 255 );
    G = ( G / 255 );
    B = ( B / 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;

    var X = R * 0.4124 + G * 0.3576 + B * 0.1805;
    var Y = R * 0.2126 + G * 0.7152 + B * 0.0722;
    var Z = R * 0.0193 + G * 0.1192 + B * 0.9505;

    X = X / 95.047;
    Y = Y / 100.000;
    Z = Z / 108.883;

    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 L = ( 116 * Y ) - 16;
    var a = 500 * ( X - Y );
    var b = 200 * ( Y - Z );

    return [ L, a, b ];
}