Besides the Airplay feature which allows you to share the whole Mac to the TV screen, Apple also provides you a way to share your family pictures from your iPhoto library to your Apple TV.
**Please make sure your Apple TV home sharing is on, or on the main screen, go to “Computer” and enter your Apple ID and password.
Go to your Mac computer, open iTunes (Make sure your iTunes is up to date), from the left side bar, click “Home Sharing”, put the same Apple ID you just use on the Apple TV.
If you do not see the left side bar, you can show it by click “View” on top of the screen, and choose “Show Sidebar”, then your iTunes will be more classic as you used to know. Or you can turn on “Home Sharing ” by going to “File” – “Home Sharing” – “Turn on Home Sharing”
Go to ”File” – “Home Sharing” – “Turn on Home Sharing” – “Choose photos to share with Apple TV”
4. Then choose the library you want to share, also you should check “including video” if you want to play the video on the TV.
5. Go to your Apple TV, go to “Computer”, and you will be able to see “Photos”