IMG Opacity

HTML

<img src="http://farm8.staticflickr.com/7183/6908744113_31404cea97_m_d.jpg"/>

CSS

/*See http://www.quirksmode.org/css/opacity.html for details*/

img {
    display: block;
    border: 4px solid #222;
    margin: 20px auto;
    /*Standard*/
    opacity: 0.5;
    /*IE 8*/
    -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
    /*IE 5-7*/
    filter: alpha(opacity=50);
}
img:hover {
    /*Standard*/
    opacity: 1;
    /*IE 8*/
    -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=100)";
    /*IE 5-7*/
    filter: alpha(opacity=100);
}