Did you ever wonder that if you blocked your images from being indexed by Google would it impact your core web content from also ranking in Google? Well, John Mueller from Google said no - blocking images from being indexed does not impact your other content from being indexed or ranked in Google.
Marie Haynes asked the question and John Mueller responded on Twitter:
no.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) August 24, 2017
He then explained that even really large sites decide not to allow Google to index their images but it has no impact on their web search rankings. Obviously it does impact their image search rankings.
Yes. Some big image sites block all their images, that's up to them to decide. It doesn't directly affect websearch.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) August 24, 2017
Forum discussion at Twitter.