I want the script below to display an Adsense add every 16th instance. Can someone help?
I don't know much PHP but I can usually figure these things out thanks to Google.

PHP Code:

<div id="images">
            <?php while (next_image(false, $firstPageImages)): ?>
            <div class="image">
                <div class="imagethumb"><a href="<?php echo htmlspecialchars(getImageLinkURL());?>" title="<?php echo getBareImageTitle();?>"><?php printImageThumb(getAnnotatedImageTitle()); ?></a></div>
            <?php endwhile; ?>

</div>

Thank you.

PHP Code:

<?php
$count = 1;
<div id="images"> 
            <?php while (next_image(false, $firstPageImages)): ?> 
     <?php if($count == 16) : ?>
                 ADSENSE CODE HERE
     <?php $count = 0; endif; ?>
            <div class="image">
                <div class="imagethumb"><a href="<?php echo htmlspecialchars(getImageLinkURL());?>" title="<?php echo getBareImageTitle();?>"><?php printImageThumb(getAnnotatedImageTitle()); ?></a></div> 
     <?php $count++; ?>
            <?php endwhile; ?> 

</div>

Thank you NullPointer. Your reply was very helpful.