When you take pictures of tall objects, the resulting photographs may have perspective distortion—the objects seem to be leaning or angled. This distortion happens when the camera is at an angle to the subjects.
To use the Perspective Correction tool to correct perspective:
On the Tools toolbar, select
the Perspective Correction tool 
.
A bounding box with corner handles appears on the image.
On the Tool Options palette, select from these options:
Grid lines To display grid lines in the box, enter the number of lines to display.
Crop image Mark this check box to crop the image back to its original size after the perspective is applied. Areas of the image that fall outside the original image size are deleted.
Drag each handle to the corner of a feature that is supposed to be rectangular. For example, the feature may be a building with sides that are angled but should be straight.
On the Tool Options palette, fine-tune the position of the bounding box by specifying the X and Y positions of the four corner handles.
Double-click the image or click Apply.
Note: To reset the perspective
correction box to the original rectangle, click Reset
on the Tool Options palette.
Using the Deform Tool to Correct Perspective