The engineers at Instagram have managed to hack their way to straighter photos using technology built-in to your iPhone. Using phone technology like accelerometers and gyroscopes, Instagram will automatically straighten your images with the click of a button.
From Instagram’s Engineering Blog:
When you take a picture in-app and tap on the new straighten icon, we use this sensor to straighten the photo automatically. In order to correct the angle, we rotate the photo by the opposite of the angle in which you held your device. Once the auto correction is applied, you can fine-tune the results using the feature’s UI.
Nothing like making my pasta snaps a little straighter with a single tap.