文本不应该拥有其父不透明度

我希望在不改变布局的情况下，图像顶部的文本不具有其父文本的不透明度。

<div class="container">
    <div class="imageHolder">
        <img src="http://www.hairstylermall.com/wp-content/uploads/short-layered-hairstyles-2013-2-200x300-short-layered-hairstyles-2013-20140813122004-53eb90341bf7e-440x425.jpg">
        <div class="messageBox">
            <h4>Something</h4>
            <p>This is dummy</p>
        </div>
    </div>
</div>

.imageHolder {
    position:relative;
}
.messageBox {
    position:absolute;
    bottom:20px;
    width:70%;
    background-color:#999;
    padding:10px;
    left:20px;
    opacity:0.5;
}

.messageBox{
   background-color: rgba(153, 153, 153, 0.5);
   color:#999;
 }

.messageBox {
    position:absolute;
    bottom:20px;
    width:70%;
    background-color:rgba(153, 153, 153, 0.5);
    padding:10px;
    left:20px;
}