How to apply a perspective warp in Adobe Photoshop.

Once you have the file open in Photoshop, select the layer you want to adjust. If your image is the background layer, copy it to another layer so none of your edits will permanently erase pixels in the original image, and you always have the option to go back. Click Layer › Duplicate Layer in the top menu.

If you want to use Perspective Warp on the entire image, go right to Step 4. To shift a single object in the image, continue with Step 2. If you want to make sure your edits affect only one object in the frame, draw a mask around it with one of the Selection tools in Photoshop. Then click Select and Mask in the options bar.

Turn the layer mask into a Smart Object to ensure that any edits you make will be nondestructive and reversible. First, select the layer mask in the Layers panel. Then, in the top menu, select Layer › Smart Object › Create Smart Object.

Select Edit › Perspective Warp from the top menu. If the feature isn’t accessible, you need to enable the graphics processor first so the program has enough memory to function. In the top menu click Photoshop › Preferences › Performance, and select Use Graphics Processor in the Graphics Processor Settings.

Click and drag to draw quads (four-sided shapes) along the planes of the architecture or other objects you want to shift. Keep the edges parallel to the straight lines in the image, and note that when you drag a corner close to another corner, they will snap together.

In the options bar, switch from Layout to Warp mode. Now you can move the object and change perspective. You can use the automatic buttons in the options bar to level the horizontal lines in your grid, straighten the vertical lines, or do both at once. You can also move the corners of the quads to where you want them. For example, you might want to shift the perspective of a building so it looks like you photographed it from the exact corner. Just shorten one side or lengthen the other to make it work. 

Shift-click (hold down the shift key while you click) to make a line vertical and move a whole side instead of just a corner. You can Shift-click multiple lines at once to keep all of the lines straight as you move your mouse. When you’re happy with your changes, click the checkmark in the options bar to close the Perspective Warp feature.

Perspective Warp may cause a loss of pixels at the edges of your frame. Fix this by selecting the Crop tool and shrinking your frame. Or use the Healing Brush tool or the Clone Stamp tool to fill in the missing pixels. For both tools, Option-click (Mac) or Alt-click (Windows) to select an area you want to copy, and then click on the area with missing pixels to fill it with the pixels you copied. (Make sure the Select All Layers option is checked in the option bar.)