Straightening a Crooked Photo
Open the photo that needs to be straightened. The photo I will use is shown below:
First select the ruler tool from the tools panel. Next you need to let Photoshop know where the straight edge should be. Draw a line in the image to represent the new straight horizontal edges shown below:
Click the Straighten button at the top of the document window.
Your frame should now appear straight as shown below:
How easy was that?