Thanks Chris! So, in my instance, should I just add that directive to the 2 pages that feature the images but are still indexed? Or should I also include it to those pages that are noindexed, just to be on the safe side?

Panic Stations! A Case Study on How to Handle an Important Page Disappearing from Google
12/2/2013 A client's homepage had mysteriously vanished from Google's index overnight, taking with it a lot of page one rankings. This post runs through the steps that I took to resolve the issue. I acted methodically yet swiftly, and in doing so managed to get the homepage back in Google's index (along with its former rankings) in less than 12 hours.