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Don't use iCloud to download photos to your Mac. Syncing is to transfer contents from your Mac to iPad and vice versa. You don't need to sync to transfer photos from iPad to your Mac.
Use iPhoto/Photos or Image Capture to download photos from your iPad to your Mac without losing anything from iPad. Better to use Image Capture application. Open Applications folder and open Image Capture. Connect your iPad to your Mac and Image Capture will recognize it. Select the iPad at left column and you will see all photos. Then you can download them to your Mac (select the photos and click Import or Import All). After downloading them to your Mac,you can import them to iPhoto/Photos app if you want.
If you have any difficulty on following the steps above, please let me know and I will continue to help you.
You can also directly download the photos from your iPad to iPhoto or Photos app. Open Photos or iPhoto app, connect your iPad and it will recognize it like a camera. Then select the device, select the photos and import and they will be imported directly to the iPhoto or Photos Library.
You don't need to use iTunes or iCloud to download the photos from iPad to Mac. iTunes syncing is mainly to sync musics, photos from Mac to iPad, movies etc between the devices.