PHOTOSHOP TOOLS - Using Rulers and Guides

In doing any perspective adjustment to an image it is a good idea to have guides to let you know what your horizontal or vertical axis really is. Otherwise you could be off by degrees without realising it until later.

1 - 2. With an image open in Photoshop, unlock the Layer as below by double clicking the padlock. This turns the image into an adjustable layer.
Turn on your Rulers Co - R so you will be able to see the true vertical and horizontal axis. Then Co - ; to make them visible or not.
3 - 4. Then with your Move Tool ‘V’, drag the edge of your rulers onto your image, like so.
5. Alternatively you can use the Grid as a guide. This is Co - “ to turn them on or off (see the header image at top)..
6. Once your guides are in place you can then adjust the image any way you like.
With the Warp command you can drag anywhere in the image to adjust the perspective. It’s very cool.

1. Unlock the Layer lock icon and click 'okay' (Copy)

2. Now the padlock icon has gone, making it a layer where you can change its properties. (Copy)

3. Arrow Tool 'V' grabbing a Ruler

4. Drag both horizontal (from the left ruler) and vertical guides (from the top ruler) and drag on to your image

5. Alternatively you can use the Grid, by Co - "

6. With guides in place whilst EDIT - TRANSFORM - WARP