How to Flip an Image in Photoshop
Photoshop has the tools you need to transform or add artistic polish to your images. For example, you can flip your images along a vertical or horizontal plane in a couple of ways. You can flip an entire image or an individual layer. In addition, you can flip selected objects within a layer while leaving the rest of the image untouched. Information in this article applies to Photoshop 14.2.1. It may vary slightly or significantly with other versions of Photoshop.
When you look at yourself in a mirror, you are actually seeing your image flipped horizontally. You can apply this mirror image special effect to your photos or other images by using Photoshop's Flip Canvas Horizontal tool found within the “Image” menu under "Image Rotation." This same tool is also found within the "Edit" menu under "Transform."
Flip Images Vertically
A vertically flipped image is mirrored also, but from top to bottom rather than left to right. The flipped image appears as a reflection of the original along a horizontal line running through the middle. Like the Horizontal Flip tool, the Vertical Flip tool is found in the "Image” menu under "Image Rotation" or within the "Edit" menu under "Transform."
Free Transform Tool
The Free Transform Tool enables you to flip an entire image or selected object horizontally by literally dragging the handles on the left side of the image to the right and vice versa. Likewise, you can flip the image vertically by moving the bottom edge to the top and the top edge to the bottom of display window. Once you select the image or layer you want to flip, you can access the Free Transform tool from the “Edit” menu or by pressing the "Ctrl-T" keyboard shortcut.
Effect on Image Layers
Flipping an image with multiple layers can have unintended consequences. The Flip Horizontal and Flip Vertical tools transform the entire canvas. If your image contains multiple layers, they all flip together as a single unit. If you want to flip only the current layer you are working on and leave the other image layers untouched, use the Free Transform tool instead.