CSS3 filter (Filter) property changes color pictures

By demonstrating modify the image colors

HTML

<div>
    <img src="http://file02.16sucai.com/d/file/2014/0704/e53c868ee9e8e7b28c424b56afe2066d.jpg">
    <img class="gray" src="http://file02.16sucai.com/d/file/2014/0704/e53c868ee9e8e7b28c424b56afe2066d.jpg">
</div>

CSS

.gray {
    -webkit-filter: grayscale(100%); 
    filter: grayscale(100%);
    opacity:0.7;
}

Renderings

Rookie Tutorial: CSS3 filter (filter) properties