If you turn your camera 90 degrees to take a photo, iPhoto usually rotates the photo during import so that it’s right side up. If you want, you can manually rotate a photo so that it’s oriented a different way.
If a photo looks crooked, you can also straighten it by rotating it up to 45 degrees in either direction.
Important: Editing a photo changes it everywhere it appears. For example, if you already added the unedited photo to a book, your edit changes appear automatically in the photo in the book. To edit a photo without changing it everywhere, duplicate the photo and then edit the duplicate.
Open the photo in edit view.
If the Quick Fixes tab (at the top of the Edit pane) isn’t selected, click it.
Click the Rotate button.
You might need to click the Rotate button multiple times to orient the photo the way you want.
You can also choose Photos > Rotate. To leave edit view without saving your changes, press Escape (Esc). To cancel all changes made during this edit session (in any of the Edit panes), click “Revert to Previous.”
Note: If you’ve made only one edit, the button is labeled “Revert to Original.”
To reverse the direction temporarily, press the Option key when you click the Rotate button.
To change the default direction, choose iPhoto > Preferences, click General, and then select one of the Rotate options.
If you’ve made only one edit, the button is labeled “Revert to Original.”
Open the photo in edit view.
If the Quick Fixes tab (at the top of the Edit pane) isn’t selected, click it.
Click the Straighten button.
Move the slider to adjust the angle of the image.
Do one of the following:
To save your changes, click Done.
To cancel all changes made during this edit session (in any of the Edit panes), click “Revert to Previous.”
Note: If you’ve made only one edit, the button is labeled “Revert to Original.”