Edit
Used for any post that has a direct image link as a source, rather than the tweet, Tumblr post, 4chan (archived) post, or other web page onto which the image was uploaded (unless the source can only be accessed as a direct image link, via a blog/gallery link, as an example).
It goes without saying that normalized sources (that is, posts with direct image link sources that end up pointing to the source post regardless, ala pximg) also don't count for this tag.
Examples
- 4chan: source:*i.4cdn.org/ / source:*images.4chan.org*
- AcFun: source:*aixifan.com*
- AC Nimingban: source:*nmbimg.fastmirror.org*
- Amazon: source:*images*amazon.com*
- Cloudfront (various): source:*cloudfront.net* - do not mark source:*cloudfront.net/photos/large/* as the post link can be extracted from them (majority consists of Twitpic images).
- Web Services (various): source:*amazonaws.com*
- Alibaba: source:*alibaba.com*
- Taobao: source:*taobaocdn.com*
- ArtStation: source:*cdn*.artstation.com/*/assets/*
- Behance: source:*://mir-*cdn*.behance.net/
- bcy.net: source:*bcyimg* / source:*img-bcy*
- Bilibili: source:*hdslb.com*
- Blogger/Blogspot: source:*bp*blogger* / source:*bp.blogspot*
- Discord: source:*discordapp.com*
- Drawr: source:*://cd*.drawr.net/
- Google: source:*googleusercontent.com / source:*sites.google.com
- Google Cloud Storage: source:*googleapis.com
- Google Drive: source:*googledrive.com
- Google Groups: source:*googlegroups.com
- Picasa(?): source:*ggpht.com
- Know Your Meme: source:*.kym-cdn.com/photos/images/
- Lofter: source:*nosdn.127.net*
- Nijie: source:*://pic0*.nijie.info/
- Pinterest: source:*://i.pinimg.com/
- Pixiv: source:*://pixiv.blogimg.jp/
- Poipiku: source:*://img.poipiku.com/user_img01/ / source:*://poipiku.com/IllustDetailPcV.jsp
- Sina (Weibo, etc): source:*sinaimg.cn*
- Tencent (QQ, etc): source:*qq.com*jpg* / source:*qpic.cn*
- Tumblr: source:*media.tumblr.com*
- Twitter: source:*twimg.com*