Digital rule of thirds tool

Mike Otley explains how Photoshop's Guides, Grid and Slices can be used to create a grid showing us the useful rule of thirds composional layout.

Photoshop users will be aware that it’s possible to place a grid over their image to help align verticals and horizons etc and that the grid can be invoked by keying Ctrl-‘.

However, it’s also possible to modify this grid so it shows a rule of thirds overlay on the image. This will help with compositional cropping in Photoshop.

Creating a rule of thirds grid

Go to ‘Edit – Preferences – Guides, Grid & Slices. Assuming this has been left at ‘Default’, you will see the following:-

We will change some parameters in the Grid section of the preference dialogue box that appears.

The changes are shown below :-

The choice of gridline colour is not arbitrary; make your own choice from the drop-down menu. ‘Custom’ is the default setting.

Leave Style set to Lines

Gridline every needs to be set to 33.33 and select Percent from the drop-down menu to the right of Gridlines every:

Change Subdivisions: to 1

That’s it.

Now when you key Ctrl-‘ with your image on display, you will see a grid representing the rule of thirds overlaid on top.

I tend to use an ordinary set-square from a geometry set to check my verticals, but should the reader wish to switch between the standard grid and the rule of thirds version, I’m sure a Photoshop Action can be written to automatically take care of this! If you do write this Action please send me a copy!

To find out more about in camera compositional techniques see this article: Beginners' guide to composition