I have the same question. I know the "originals" URL carries the link to the original image, which is as good as it's going to get. But sadly, my config file jujitsu just isn't up to par. I found an older post that said you could pass in a command line switch like "--match-URL" and then a substring (in this case "original") to make sure that any URLs grabbed contained that substring. But that's not working. So, if someone knows how to do the config file for that, I'd be forever in their debt!

Followup: Ok, so, I ran a -v run against some Pinterest pages. It's showing that it's downloading the 'originals' images for me. I don't have any kind of URL management in my config file for it. Maybe you have something in yours about URLs that's preventing the system from grabbing the originals?