Add whitelists to allow image use on e.g. facebook.com and twitter.com and whitelist by referrers to allow web crawlers such as googlebot index your images.
Imaguard allows white listing by both referrers and by user agent. When a referrer is white listed, the referrer can directly access the image and include it on their own site. When a user agent is white listed, that user agent will be allowed to directly access the image, regardless of referrer. It is common to whitelist known search engine crawlers (there is a list of known google crawlers in the readme file) but you can also whitelist certain mobile devises.