将彩色图片转换为黑白

1. 不同的浏览器将彩色图片显示为黑白图片的css，这里采用css filter

• firefox

img {
    filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'grayscale\' x=\'0\' y=\'0\' width=\'100%\' height=\'100%\'><feColorMatrix type=\'matrix\' values=\'0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0 0 0 1 0\'/></filter></svg>#grayscale");
}
img:hover{
    filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'grayscale\' x=\'0\' y=\'0\' width=\'100%\' height=\'100%\'><feColorMatrix type=\'matrix\' values=\'1 0 0 0 0,0 1 0 0 0,0 0 1 0 0,0 0 0 1 0\'/></filter></svg>#grayscale");
}

•  IE

img{ 
   
    -webkit-filter: grayscale(100%);
    -moz-filter: grayscale(100%);
    -ms-filter: grayscale(100%);
    -o-filter: grayscale(100%);    
    filter: grayscale(100%);	
    filter: gray;
}
img:hover {
    -webkit-filter: grayscale(0);
    -moz-filter: grayscale(0);
    -ms-filter: grayscale(0);
    -o-filter: grayscale(0);    
    filter: grayscale(0);	
}