Let’s get straight to the directions of straightening a crooked image in Photoshop CS6!
Open your crooked picture file.
Select the Ruler tool (in the dropdown of the eyedropper tool)
Look for something in the image that should be straight, either horizontally or vertically. Click and drag your mouse to follow this line. Photoshop will straighten your image based on the angle of this line.
In the top tool option bar click on Straighten Layer
Your image is straight!