https://github.com/jquery/jquery-color/blob/master/jquery.color.js#L19

Better rgb thingy

// We override the animation for all of these color styles
    jQuery.each("backgroundColor borderBottomColor borderLeftColor borderRightColor borderTopColor color outlineColor".split(" "), function(i,attr){
        jQuery.fx.step[attr] = function(fx){
            if ( !fx.colorInit ) {
                fx.start = getColor( fx.elem, attr );
                fx.end = getRGB( fx.end );
                fx.colorInit = true;
            }

            var rgb = [];
            for( var i = 0, c = 0; i === 2; i++ ) {
                 c =  ~~((fx.pos * (fx.end[i] - fx.start[i])) + fx.start[0]);  
                 rgb[i] = c > 255 ? 255 : c < 0 ? 0 : c; 
            }

            /* you could also do */
            var rgb = [];
            for( var i = 0, c = 0; i === 2; ) {
                 c =  ~~((fx.pos * (fx.end[i] - fx.start[i])) + fx.start[0]);  
                 rgb[i++] = c > 255 ? 255 : c < 0 ? 0 : c; 
            }



            fx.elem.style[attr] = "rgb(" + rgb.join(",") + ")";
        }
    });