<!doctype html>
<html>
<body style='margin:0px; display: flex;'>
<img id='sizer'/>
<script>
// The desired size should be specified in the url in the search portion
// like this ?widthDimension:heightDimension.
var parsedParameters = window.location.search.substring(1).split(':');

// Set the sizes.
var elementToSize = document.getElementById('sizer');
elementToSize.style.width = parsedParameters[0];
elementToSize.style.height = parsedParameters[1];
</script>
</body>
</html>