I think that imgur image system needs some explaination :
The first link isn't an image at all ! Imgur uses url rewriting and wrapping.
Url rewriting :
http://imgur.com/a/DbQIP.jpg is a link that asks a scripted page (php) on imgur.com to get the resource DbQIP.jpg, which is completely different from DbQIP.JPG, DbQIP.jPg, and so ...
You know that http://imgur.com/a/DbQIP is just a resource, but to show it to users, imgur wraps that resource in html code, so the user can interact with (comments, likes, ...) : this is in fact imgur website UI (user interface). Because of that, the forum detects the link as html, and not as an image.
Now, go to this link (the one without ".jpg"), right click on the picture, then click on "view image" ... and voilà !
You got the (almost) real link to your pic : https://i.imgur.com/h5gX9Ty.png
So what has changed : first your pic is a .png one not .jpg as you expected, then, notice the 'i' before domain name ... it's called subdomain. Imgur uses another (or lots of) server to host the images. This is this picture (resource) that the script i talked about above gets and wraps.
and here, no script to wrap them, you get them in "raw".
If you have other questions feel free to ask