If you used Photostream on iCloud then they would already be on your iMac when you got back.
"You can transfer images from iPad to iMac by using USB flash drive & camera connection kit.
• Plug the flash drive into your computer
• Create new folder titled DCIM
• Put your movie/photo files into the folder
• Files must have a filename with exactly 8 characters long (no spaces) plus the file extension (i.e., my-movie.mov; DSCN2569.jpg)
• Now plug the flash drive into the iPad using the camera connection kit
• Open the Photos app, the movie/photo files should appear & you can import.
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Image Capture (also on your iMac) can also be used if for whatever reason you're not using iPhoto.