Hey dudes. I'm sure you've noticed that screenshots that have been "shared" on PS4 look like shit.
I just found a way to export without any compression!
Go to messages and send a picture, hit screenshot, choose your pic and send to somebody (or like a dedicated screenshot account maybe?) Go to the playstation app (mobile), go to messages and you can see the full res shot you've taken, save it to your phone and do with it as you please.
I just dropboxed mine over to my desktop :)
This could be easier if there was a way to check your messages on a PC but i'm pretty sure you can't.