Warning with https site when stream has an image from a shared link

Not sure if there's a solution to this but I've recently moved my site to https:// and I notice the nice green security indicator I get in the browser address bar, switches to a warning sign when the community stream includes an image taken from another site (in the case of my stream URL I've given, it's an image auto-created from the 'share link' option).

Any way around this?
Thanks!