It’s helpful to tilt your head as you tilt the device so that you have a better sense of the final crop. Simply tilt the iPad or iPhone to the left and right as you do, you’ll notice that the photo remains upright. iPhoto then calls on the gyroscope in your device to help you straighten the image. Choose a photo you want to straighten and then hold the iPad or iPhone up in front of you. What happens when your photo has no visual cues, but still feels off-kilter? iPhoto for iOS has one more strategy to assist you, and it’s a lot of fun. A grid overlaid on your photo as you turn the dial, lets you straighten with visual cues in your photo. The Crop & Straighten mode places a dial under your photo, and you can straighten your photo simply by dragging the dial left or right. Unfortunately, iPhoto can’t always detect a horizon line and that means you’ll have to make the adjustment yourself. To proceed with straightening, simply tap the arrow icon at the right.
If the photo displays a white line across it with icons at either end, then that means a horizon line has been detected. Now tap the Crop & Straighten icon in the bottom left. Open iPhoto, choose a photo and then tap Edit. The first is by auto-detecting a strong horizon line. IPhoto for iOS allows you to straighten your photos in a few smart ways.
Although iPhoto for iOS isn’t quite as robust as its OS X counterpart, it’s a very capable image editor-and it can do a few cool tricks you simply can’t do on your Mac.