When you want to stack two images in Photoshop, you can use the stacking tools or the layers palette. The stacking tools let you stack images in different ways, but the layers palette is more versatile. You can stack images using either a left-to-right or a right-to-left order. To stack two images in the layers palette, select one image and press Ctrl+L (or Cmd+L). Then select the other image and press Ctrl+R (or Cmd+R).
