Syncing photos from iTunes to an iOS device will resize them so they are optimised for display on the mobile screen. This is not intended as a method of moving full sized files to the OS device as part of an editing workflow.
Airdrop is another option for moving the full size files but that is still a bit flaky in experience between Mac and iOS.
Airdrop is another option for moving the full size files but that is still a bit flaky in experience between Mac and iOS.