This is a bot that finds graphs on Twitter that use matplotlib's Jet colormap, and suggests their author to use the new Viridis colormap instead (which will be the new default).
It is deployed as @colormap_bot.
The way the colormap is detected is shown in more details in this notebook.
Please don't hesitate to contribute! My image processing skills are weak, and since I spent more time on this than initially anticipated, I would welcome feedback of any kind.