css vertical alignment trick

index.html

<div class=frame>
    <span class="helper"></span><img src="http://jsfiddle.net/img/logo.png" height=250 />
</div>
<div class=frame>
    <span class="helper"></span><img src="http://jsfiddle.net/img/logo.png" height=25 />
</div>
<div class=frame>
    <span class="helper"></span><img src="http://jsfiddle.net/img/logo.png" height=23 />
</div>
<div class=frame>
    <span class="helper"></span><img src="http://jsfiddle.net/img/logo.png" height=21 />
</div>
<div class=frame>
    <span class="helper"></span><img src="http://jsfiddle.net/img/logo.png" height=19 />
</div>
<div class=frame>
    <span class="helper"></span>
    <img src="http://jsfiddle.net/img/logo.png" height=17 />
</div>
<div class=frame>
    <span class="helper"></span>
    <img src="http://jsfiddle.net/img/logo.png" height=15 />
</div>
<div class=frame>
    <span class="helper"></span>
    <img src="http://jsfiddle.net/img/logo.png" height=13 />
</div>
<div class=frame>
    <span class="helper"></span>
    <img src="http://jsfiddle.net/img/logo.png" height=11 />
</div>
<div class=frame>
    <span class="helper"></span>
    <img src="http://jsfiddle.net/img/logo.png" height=9 />
</div>
<div class=frame>
    <span class="helper"></span>
    <img src="http://jsfiddle.net/img/logo.png" height=7 />
</div>
<div class=frame>
    <span class="helper"></span>
    <img src="http://jsfiddle.net/img/logo.png" height=5 />
</div>
<div class=frame>
    <span class="helper"></span>
    <img src="http://jsfiddle.net/img/logo.png" height=3 />
</div>

style.css

.frame {
    height: 25px;      /* equals max image height */
    width: 160px;
    border: 1px solid red;
    
    text-align: center; margin: 1em 0;
}

.helper {
    display: inline-block;
    height: 100%;
    vertical-align: middle;
}

img {
    background: #3A6F9A;
    vertical-align: middle;
    max-height: 25px;
    max-width: 160px;
}

http://stackoverflow.com/questions/7273338/how-to-vertically-align-an-image-inside-div