Really, how? I would have thought that running the image processing on that backend would be much more expensive than serving the relatively static website?
Who is DDoSing you? This website is not a high-profile target, I'm not sure why anyone would be interested in attacking this. Or do your logs say otherwise?
By 'traffic routing' do you mean CDN, or reverse-proxy or what? A single server with properly-configured client-side HTTP caching should do the trick for serving a static site.
