If you handhold the camera for most of your shots rather than using a tripod, you can be sure that some of your photos are going to come out a bit crooked. Here’s a quick way to straighten them accurately in just a few short steps.
Open the photo that needs straightening. Choose the Measure tool from Photoshop’s Toolbox (it looks like a little ruler, and it’s hidden behind the Eyedropper tool, so just click-and-hold for a moment on the Eyedropper tool until the Measure tool appears in the flyout menu).
Try to find something in your photo that you think is supposed to be straight (the horizon ...