Mentioned by Tyler during a meeting: add the ability to diff images in Gerrit. There is a JavaScript plugin for it:
https://gerrit.googlesource.com/plugins/image-diff
https://github.com/GerritCodeReview/plugins_image-diff#image-diff
That requires an inline build with bazel build plugins/image-diff to install the dependencies.
The plugin can be tested against
https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/902211/1/static/images/project-logos/dkwikimedia.png which slightly change the Danmark Wikimedia logo:
| Before | After |
|---|---|
 |  |
Which then let you see the differences (using cyan but that can be changed via a color picker):
Make the images transparent to better see the diff:
Or go in gray mode:
There are some CSS glitches though but that do not seem too worrysome.