You can get some idea of organic image traffic if you use Google Analytics:
Acquisition > All Referrals > click on google and look at /imgres. If you want to see where the traffic is going to (to get an idea of which images) click /imgres and on the Secondary dimension dropdown go to Behaviour > Landing Page.
If it's as simple as redirecting using the same slugs (hence one global redirect rule) then I would redirect the images. If it's complicated then I might not bother, depending on whether image search leads to many visits and conversions to your site or not. Usually image traffic doesn't convert well. If you're migrating to a new domain and keeping the same folder structure it should be as easy as doing one global redirect?
Rather than redirecting I'd most likely take the opportunity to make the filenames of images more friendly than ce7aeffb1e5bdfc8d4288885c52de8e3.jpg by using short descriptive filenames.