Transfer Photos

To copy photos that were taken with the iPad, copied to it via the camera connection kit, or saved from emails/websites : Import photos and videos from your iPhone, iPad, or iPod touch to your computer - Apple Support

To copy photos that were originally synced from a computer you will need a third-party app on your iPad such as Simple Transfer which can copy them off via your wifi network. But as photos are 'optimised' when they are synced to the iPad, any that you then copy back to a computer may not be exactly the same as they originally were on your computer (e.g. their dimensions may be different, colours and sharpness may not look the same).