Pretty sure this has been said previously but I'l reiterate it for anyone who hasn't seen it.
If you want to take the screenshots directly from the PS4 without using Facebook or Twitter:
Download the Playstation app onto your smartphone from the Play Store/App Store
Create a
new PSN ID specifically for the app.
Friend request your new ID to the current one on the Playstation
Then use the PS4 to send the screenshots via a message from your PS4 account to the one on the smartphone
Then there's an option to save the image when you view it on the smartphone, do that
Then simply plug the phone into your PC/Mac and just grab the images from the phone
It's simple to do but the images are still slightly compressed. Until Sony patch a copy to USB function this is the only way you're going to get semi-decent images without a capture card (to my knowledge anyway).
Anyway, here's a KZ grab and two AC4 ones using the above method