Can't get my photos and videos from iPad
For some reason iTunes photo sync (iOS Device -> Photos) is quite restricted regarding what you do with those photos after they are on the iOS device. Even Apple specifically says that you can't sync those photos from your iOS device to your computer.

As a result, I suggest trying iExplorer to copy the photos from the iPad to your computer.

If you had AirDrop on both devices, you could use that to transfer the pictures, but it would be a little painstaking as you would have to tap every picture to transfer.