What are you trying to accomplish? If the origin servers are returning a response with http urls and you want to rewrite to https, you may be better off simply proxying https on the client side of the virtual IP and communicating with the origin (server side) via HTTP.
Usually, when I do HTTP response rewrites like this, it is when there is an ancient or broken server that uses absolute paths with the inside non routeable IP address as the host. However, in this case, I generally would not filter on the content-type because there would be a few -- lots of elements being loaded by a single HTTP page -- generally text, various images, and perhaps some hosted files like PDFs.