September 27 2007
How to create a guide in Photoshop and the Gimp for analyzing digital camera images using the classic artist’s composition tool, the Rule of Thirds.
The Rule of Thirds is a classic compositional guide from the art world, with just as much validity in the age digital image era.
The suggested technique in painting is drawing a Rule of Thirds grid onto the blank canvas as a guide to laying out the new work of art. Draw the grid using a pencil and cover it with the painted image.
This process is the reverse where the digital image editing software superimposes a Rule of Thirds grid on top of a digital image.
This is useful as a starting reference when reviewing the composition of images and the visual balance of elements within the image.
Use it review your existing images and review your composition technique and may be find out why slightly different versions of the same picture seem more pleasing than others.
The grid is a useful guide when making decisions on cropping images in digital image editing software.
Of course, the grid lines are not indelibly inscribed into the image and are turned off with a mouse click.
How Adobe Photoshop CS2 does it
This takes a little bit of work to configure using several menu commands. The good news is once you do the basic configuration it remains in your Photoshop preferences and is available for all images.
The first step is to open the guides and grids dialog box and set the grid pattern to gridlines every 33%, which is a third, with the subdivisions set to one.
There are options for changing the color and line type to suit personal preferences and the color of images reviewed.
Then to make the grid visible go to the view menu, select the show sub-menu and click the grid option. There is also a keyboard shortcut shown in the menu.
How Gimp does it
The Gimp does it slightly differently to Photoshop. From the gimp site you can download a script file that will draw the Rule of Thirds grid on a new layer in your image.
Place the downloaded file in the Gimp script file folder on your computer and it becomes available to the Gimp.
The color and width of the gridlines can be set to suit the image.
Now, technically the grid is part of the image file, as the layer is part of the image information. The eye icon in the Gimp’s layer dialog box controls viewing or hiding the grid. The image can be printed with the grid staying hidden, or once you have finished using the grid, delete the layer.
The Adobe method is more elegant as the grid is never part of the image. However, layers are a very important part of the digital darkroom so implementing the Gimp solution should not present long-term problems to photographers.