Although search engine traffic is the lifeblood of many sites, referrals from image searches are worse than worthless. Unless you’re selling stock photography, or need to superficially inflate overall traffic figures a tiny bit, you probably won’t want to encourage people to visit to nab your images for their site/presentation/homework. Image search users are generally looking for pictures to download or hotlink, not sites to read.

So to discourage search engines from spidering images (and any other static files that shouldn’t be indexed anyway), simply forbid access to the appropriate folders in the site’s robots.txt file, e.g.:

User-agent: *
Disallow: /templateAssets/
Disallow: /content/images/

It’s a good idea to do this at launch if possible, as in the past I’ve noticed some search engines being very slow to let go of images once they have them.