How to check resolution of image coming into OBS?

[huedoku]

How can I check the actual resolution of the image coming into OBS?

1. I have an external camera that should be 1080p but it looks the same or worse than the (Built In) HD Camera MBP which is 720.
2. I also have two HDMI capture cards bringing in an image from another computer.

How do I confirm what the resolution of the image is?
Is there something in settings of preferences?
Or a workaround? Export the image and just check it by zooming in?