Meta Stack Exchange has announced their roadmap to serving and uploading HTTPS images. Any images already uploaded to Stack Exchange's Imgur site will be automatically converted. Those that are linked to external sites will be made link-only.
After [https] is enabled, old posts that have HTTP images, accessible via HTTPS, will be edited accordingly. This will be an actual markdown change, attributed to the Community user, posts won't be bumped.
We'd like to prevent this from happening. Let's take the time to update our questions to point to HTTPS versions of our questions. Other sites, such as SciFi/Fantasy Stack Exchange, are undergoing similar efforts. This will unfortunately bump a lot of questions to the front page, but I think that this effort is best in the long run.
This Stack Exchange Data Explorer query should find all of them. At the time of this writing, there are 26 questions needing attention, so it's not a huge effort.
It looks to me like the majority of external HTTP images are for Magic cards. Unfortunately, none of the sites, (including Wizards' own Gatherer) support HTTPS at this time. Fortunately, we can upload them via the Stack Exchange image uploader, which will automatically future-proof them, as well as make sure they will still exist if the external site goes down.
Speaking of which, it does look like we have a few cases of the external site going down with these images. For instance, I found Hex board game strategy had an externally hosted image to a website that no longer existed. Fortunately, I was able to find it on Archive.org from a few years ago and was able to upload it to Stack Exchange's Imgur.
So to recap:
- Find images that are externally hosted via HTTP
- Either find HTTPS equivalents or upload them via the Stack Exchange image uploader (I think that uploading to SE would be preferable, in case the external link goes down)
- If the external link is dead, try to find an old copy on Archive.org or elsewhere