The stock iPhone Photos app has many built-in editing features. These make it possible to change and customize images right in iOS 7 before sharing or downloading the photos to a computer. One basic function is cropping, which can improve photos by recomposing what's visible in the frame.
To begin cropping an image from either the iPhone camera roll or an album, start by opening the Photos app and viewing the image you wish to crop. Tap Edit in the upper right corner to get started. Next touch the square crop icon in the lower right corner to enter photo crop mode. From here, there are two options to shave off parts of a photo.