Originally Posted by Adobe Photoshop Help
Rotating and flipping entire images
The Rotate Canvas commands let you rotate or flip an entire image. The commands do not work on individual layers or parts of layers, paths, or selection borders.
Rotating images A. Flip Horizontal B. Original image C. Flip Vertical D. Rotate 90° CCW E. Rotate 180° F. Rotate 90° CW
To rotate or flip an entire image:
Choose Image > Rotate Canvas, and choose one of the following commands from the submenu:
180° to rotate the image by a half-turn.
90° CW to rotate the image clockwise by a quarter-turn.
90° CCW to rotate the image counterclockwise by a quarter-turn.
Arbitrary to rotate the image by the angle you specify. If you choose this option, enter an angle between -360 and 360 in the angle text box. (In Photoshop, you can select CW or CCW to rotate clockwise or counter-clockwise.) Then click OK.
Flip Canvas Horizontal (Photoshop) or Flip Horizontal (ImageReady) to flip the image horizontally, along the vertical axis.
Flip Canvas Vertical (Photoshop) or Flip Vertical (ImageReady) to flip the image vertically, along the horizontal axis.