Let’s see, this is a 1700 × 480 image:
Seems fine. Did you override CSS on your site, is that interfering? I can’t repro any problem with a wide image.
I also clicked through and I don’t see any problem on your site, with that topic either. All the images look fine and not artificially cropped.
Note that nesting quotes (or just quotes) inhibit the width of the post so you may observe oddities in those cases
Like so, imagine this was an image