png兼容IE6的方法

1、通过CSS滤镜使背景图的PNG对IE6进行兼容

定义一个样式,给某个div应用这个样式后，div的透明png背景图片自动透明了。

<style>
    body{background: lightblue;}
    .png{
        width: 550px;
        height: 500px;
        background-image: url(pic.png)!important;/* FF IE7 */
        background-repeat: no-repeat;
         _filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='pic.png');  /*IE6*/
         _ background-image: none; /* IE6  */
         overflow: hidden;
    }
</style>    

2、通过JS，插入一段代码，实现img标签png兼容IE6的问题

<script language="JavaScript">
        function correctPNG() // correctly handle PNG transparency in Win IE 5.5 & 6.
        {
            var arVersion = navigator.appVersion.split("MSIE")
            var version = parseFloat(arVersion[1])
            if ((version >= 5.5) && (document.body.filters))
            {
                for(var j=0; j<document.images.length; j++)
                {
                    var img = document.images[j]
                    var imgName = img.src.toUpperCase()
                    if (imgName.substring(imgName.length-3, imgName.length) == "PNG")
                    {
                        var imgID = (img.id) ? "id='" + img.id + "' " : ""
                        var imgClass = (img.className) ? "class='" + img.className + "' " : ""
                        var imgTitle = (img.title) ? "title='" + img.title + "' " : "title='" + img.alt + "' "
                        var imgStyle = "display:inline-block;" + img.style.cssText
                        if (img.align == "left") imgStyle = "float:left;" + imgStyle
                        if (img.align == "right") imgStyle = "float:right;" + imgStyle
                        if (img.parentElement.href) imgStyle = "cursor:hand;" + imgStyle
                        var strNewHTML = "<span " + imgID + imgClass + imgTitle
                                + " style=\"" + "width:" + img.width + "px; height:" + img.height + "px;" + imgStyle + ";"
                                + "filter:progid:DXImageTransform.Microsoft.AlphaImageLoader"
                                + "(src=\'" + img.src + "\', sizingMethod='scale');\"></span>"
                        img.outerHTML = strNewHTML
                        j = j-1
                    }
                }
            }
        }
        window.attachEvent("onload", correctPNG);
</script>