All new Apple iMac computers come with the iLife software suite automatically installed. The iLife suite includes iPhoto, which is an image application that can be used to import pictures from digital cameras and manage your photo library. You can move photos from the iPhoto library on your iMac to your iPad device by configuring image syncing in iTunes. The images you sync from your iMac are accessible in the Photos app on the iPad.
Launch the iTunes application on your iMac.
Connect your iPad to your iMac using an iPad USB transfer cable.
Highlight the name of your iPad from the "Devices" list on the left side of the iTunes window.
Click on "Photos" at the top of the iPad configuration page.
Check the box next to "Sync Photos" and then choose "iPhoto" from the adjacent drop-down menu.
Use the available radio buttons to choose whether you want to move all of your iPhoto data or only certain albums, events and photos.
Press the "Apply" button in the lower-right corner of the window to save the syncing settings and move the photos from your iMac to your iPad.