Picture Problems

Apologies, I've received an email telling me that some of my pictures are not showing correctly in archived posts. Sadly, this has proved to be correct. Curiously, the same pictures are shown perfectly on my related Pinterest page. 

I've tried everything that I've been recommended to do to correct the problem but nothing is working. I'm stumped! I've done nothing different at my end and all of the missing photos show clearly in the record of posts.

If any reader has experienced this problem before and can tell me how to cure it, I'd be very, very grateful.