I think this is new, a new way to report images as being offensive or having issues in Google's main web search results. Sunny sent this to me on Twitter and I think it is new, but basically there is a "report images" button that when you click it, it lets you report specific images to Google.
Here are the steps:
(1) Click the report images link:
(2) Then click on the "Report" button on the images you find offensive:
You can report images in image search and now in web search. But the way to report these images have changed throughout the years.
Forum discussion at Twitter.