"Rule of Thirds" and "Golden Mean" and "Golden Spiral"

Evan Golub
Department of Computer Science
Human-Computer Interaction Lab
University of Maryland

PhotoCropr is a .NET application that can be used to generate and explore croppings of images using either the "Rule of Thirds" or the "Golden Mean" to place a center-of-interest (currently determined by the user) in one of several specific positions in the new image. The application can either display four previews of possible croppings, created using either the "Rule of Thirds" or "Golden Mean" crosshairs to position the center-of-interest, or those four options augmented with two central croppings; one where the center-of-interest appears centered horizontally, but on the upper rule-of-thirds line, and one where the center-of-interest has been fully centered in the frame. In both display variants, the user is able to adjust the zoom level for all croppings while keeping the center-of-interest in the same relative position in the frame of each.

For some more information about composition rules such as the "Rule of Thirds" and "Golden Mean" you might want to visit the Composition Rules Visualizer page.

This is an application created during work on an image modification project. It is posted for free for entertainment purposes.

The first step is to load an original hi-resolution image, and then click on a point-of-interest (such as the middle of the image's center-of-interest).

Figure 1: An image that we want to crop based on the position of a particular point-of-interest.

The application will then present previews of possible croppings, one for each of the four possible placements of the point of interest on a "Rule of Thirds" or "Golden Mean" intersection point, and if selected, one for each of the two center-based placements. Examples on this page use the "Rule of Thirds" option, but equally apply to the "Golden Mean" option.

Figure 2: The four preliminary "rule of thirds" croppings.

Once the point-of-interest has been selected and the four preliminary croppings presented, you can move the slider below the images to zoom in or out. This will maintain the position of the point-of-interest while changing the framing of the image.

Figure 3: View of the cropping options after zooming in some more.

Figure 4: View of the cropping options after zooming out.

You might notice that in three of the four previews in Figure 4, there is not enough original image available to fill the frame of the cropping so you see some rose-colored edging. If one of these is selected, the "out-of-bounds" area will appear black in the output file. The slider is configured based on the size or the original image, the size of the output image, and the point you selected such that it will not allow you to zoom out to a point where all of the cropping options have "out-of-bounds" areas.

To save one of the cropped versions, just click on the preview of the one that you like. A save dialog will come up pre-populated with the original filename appended with a quadrant code (NW, NE, SW, SE). Several output sizes are available in 4:3, 3:4, 3:2, and 2:3 aspect ratios. There are also three output sizes available that are relative to the source image's original size and aspect ratio. The default output size is 800x600 or 600x800 (depending on the orientation of the original image) but the orientation as well as the output size can be altered (within the provided options) under the OutputSize menu after you open an original image. You can also change the default output size through the Settings dialog under the File menu. The Settings dialog also allows you to change the color used for the out-of-bounds indicator as well as whether you want to preserve EXIF data from the original image when saving the cropped version.

Figure 5: The four "Rule of Thirds" croppings augmented with two more cropping previews.
The point-of-interest centered horizontally but aligned on the upper rule-of-thirds line, and the point-of-interest dead-center in the frame.

Regardless of composition rule selected, while adjusting the zoom level for the previews, the user is able to view those previews with the composition rules (ie: "Rule of Thirds" or "Golden Mean" or "Golden Spiral") lines superimposed upon them by going to the Superimpose menu, and checking Show Lines. If that option is checked, whenever the mouse is not positioned over the zoom adjustment trackbar, the lines will appear on top of the previews. The color and width of those lines can be adjusted under the Superimpose menu as well.

Figure 6: The cropping previews with the "Rule of Thirds" lines superimposed.

While less commonly used than the "Rule of Thirds" or "Golden Mean" are, the current version also supports positioning the point-of-interest on the origin of the "Golden Spiral". Below is an image of a nautilus shell found at a publically accessible web gallery ( and viewed inside PhtooCropr. The zoom level has been adjusted to bring the shell into alignment with the "Golden Spiral".

Figure 7: A nautilus shell cropped using the "Golden Spiral".

Figure 8: Original image.

Figure 9: Cropped image.

Of course, it all comes down to the question of "Which do you find more visually appealing?" This is a question you need to answer as you explore different cropping options with this tool.

The idea of having multiple previews of the croppings, all being controlled by the same zoom slider, was inspired by SideViews, developed by Elizabeth Mynatt and Michael Terry at Georgia Tech.

A future version of this application might add an option to display an enlarged preview of any displayed cropping by mousing-over that preview (inspired by the PhotoMesa Image Browser, developed by Ben Bederson, Bongwon Suh, and Hyunmo Kang at The HCIL@UMD).

This is a preliminary stage in a project to automatically generate croppings without the user being required to manually identify the point-of-interest in an image.

If you are interested, you can read a draft of a technical report describing the project's goals. Some of the research discussed in this draft will be performed in the future.

You can download either the Version 0.77 executable or a ZIP file containing the executable.

This software is provided for free for entertainment purposes only.
If you are interested in using this software for commercial purposes contact the author, Evan Golub, at

DISCLAIMER: This software is provided on an "as-is" basis, without warranty of any kind, express or implied, including but not limited to warranties that the software is free of defects, merchantable, fit for a particular purpose or non-infringing. User bears the entire risk as to the quality and performance of the software. Should the software prove defective in any respect, user assumes sole responsibility and liability for the entire cost of any service and repair in connection therewith. No use of this software is authorized except under this disclaimer.

This page last modified on Sunday, 30-Jun-2013 16:53:01 EDT.