I added these lines to hosts file and now some images (mostly i.stack.imgur.com urls) are visible. Actually, I viewed dozens of questions and can see images without any problem. It shouldn't be that simple.
107.21.3.138 apidocs.imgur.com
151.101.36.193 api.imgur.com
104.16.53.111 help.imgur.com
151.101.36.193 blog.imgur.com
52.23.39.2 browserevents.imgur.com
151.101.36.193 p.imgur.com
151.101.36.193 s.imgur.com
151.101.36.193 store.imgur.com
151.101.36.193 i.imgur.com
151.101.36.193 i.stack.imgur.com
151.101.60.193 imgur.com
151.101.36.193 m.imgur.com