Does anyone know how to determine this value?  Or how this works?

        <div class='slide template1' data-ratio='1.44' data-background='#fff'>
            <img src='gallery/filename.jpg' width='1500' height='1000' alt='' />
        </div>

Changing this value alters the image dimensions, I've determined.

I'm referencing a page that has these files linked in it:

<script type='text/javascript' src=' http://code.jquery.com/jquery-2.1.1.min.js'></script>
<script type='text/javascript' src=' http://code.jquery.com/jquery-migrate-1.2.1.min.js'></script>
<script type='text/javascript' src='js/jquery.plugins.js'></script>
<script type='text/javascript' src='js/docready-7.js'></script>

Is anyone familiar with this? 

Thanks.