Your iPhone or iPod touch makes for a handy camera, and both can take nice images. That doesn't, however, mean you won't need to make some quick adjustments on the go. You can turn to a long list of apps designed to help with that, including Apple's own iPhoto, but if you only need to make some minor adjustments, the Photos app has a nearly-hidden editor just waiting to help out.
Tap the Edit button (left) to show the image adjustment tools (right)
To access the built-in image editing tools in the Photos app, just tap on an image in your camera roll or any photo album. Now tap Edit -- it's in the upper right corner of your iPhone, iPad or iPod touch display. From here you can rotate an image, apply Auto Enhance, correct red eye, and crop. Once you finish your edits, tap Save.
You can't alter images with Photo's editing tools to the same extent as other apps, but it's handy, and for many of the adjustments people need to make, it's also plenty.