CSS改变png图片颜色

div.icon{height:20px;width:20px;overflow: hidden;}
            .icon .icon{width: 20px;height: 20px;display:block;position: relative;left: -20px;border-right: 20px solid transparent;
                background: url(img/icon.png) no-repeat;-webkit-filter: drop-shadow(#000 20px 0);filter: drop-shadow(#000 20px 0);   
            }

<div class="icon">
            <span class=‘icon‘ id=‘icon‘></span>
        </div>
        <input type="color" id=‘color‘ />

document.getElementById(‘color‘).onchange = function(){
            var c = this.value;
            document.getElementById(‘icon‘).style.webkitFilter = ‘drop-shadow(‘+c+‘ 20px 0)‘;
        }