As I mentioned in my comment, your best bet is to opt for attempting to render HTML to an image.
Here is the link for a library that will allow your to render html to an image:
http://htmlrenderer.codeplex.com/
Here is code that does exactly what you're asking:
http://amoghnatu.wordpress.com/2013/05/13/converting-html-text-to-image-using-c/
Now all you have left is to get the html, since I'm assuming you don't want this to render to the browser prior to generating this image - you should look into grabbing the rendered html from the aspx page on the server prior to returning it, and then just return the image. To render a page:
https://stackoverflow.com/a/647866/1017882
Sorted.