Group hover over state

HTML

<div class="green">
    <img src="http://i67.tinypic.com/2433fok.jpg"/>
    <img src="http://i67.tinypic.com/2433fok.jpg"/>
    <img src="http://i67.tinypic.com/2433fok.jpg"/>
</div>

<div class="red">
    <img src="http://i65.tinypic.com/fy1ieq.jpg"/>
    <img src="http://i65.tinypic.com/fy1ieq.jpg"/>
    <img src="http://i65.tinypic.com/fy1ieq.jpg"/>
    <img src="http://i65.tinypic.com/fy1ieq.jpg"/>
    <img src="http://i65.tinypic.com/fy1ieq.jpg"/>
    <img src="http://i65.tinypic.com/fy1ieq.jpg"/>
</div>

<div class="blue">
    <img src="http://i65.tinypic.com/sz7mnp.jpg"/>
    <img src="http://i65.tinypic.com/sz7mnp.jpg"/>
    <img src="http://i65.tinypic.com/sz7mnp.jpg"/>
    <img src="http://i65.tinypic.com/sz7mnp.jpg"/>
    <img src="http://i65.tinypic.com/sz7mnp.jpg"/>
    <img src="http://i65.tinypic.com/sz7mnp.jpg"/>
    <img src="http://i65.tinypic.com/sz7mnp.jpg"/>
</div>

CSS

img {  
  position:relative; 
  display:block; 
  float:left; 
  width:auto; 
  height:200px; 
  -webkit-filter: brightness(100%); 
  -moz-filter: grayscale(100%); 
  filter: grayscale(100%); 
  filter: gray;
}

div:hover img {  
  -webkit-filter: brightness(80%); 
  filter: grayscale(0%); 
  filter: gray;
}