Instructions for "Toe Indexer"

“Toe Indexer” is a macro program for ImageJ, a flexible image analysis program that can run user-written macros within it, thereby extending and refining its functionality. It is produced and maintained by the NIH and is distributed for free, as are a number of macros written by researchers in a variety of fields. You can visit the ImageJ website and download "Toe Indexer".

The macro, “Toe Indexer,” allows easy measurement of footprints and calculation of toe index, as defined by Webb et al. (2006)"Evaluating and improving footprint measurement for clinical and scientific testing," Anthropologie, 44:269-279. The new techniques establish a longitudinal axis of the footprint, which is required for many other measurements, and define a functionally meaningful point from which to measure toe length. Toe length is divided by foot length to give toe index, a parameter which appears to be useful in ontogenetic studies and has been used to compare the Laetoli footprints with those of more modern hominins.

Because the structure of “Toe Indexer” is fairly straightforward and the written code is well ‘commented,’ it is easy to make minor alterations. Furthermore, brief instructions for each step are printed in a "Log" window as the user proceeds, as are intermediate results of the various measurements and calculations. This output can be customized by adding and deleting various calculations and their associated "print" commands.

1. Open ImageJ.

2. Install the plugin "Toe Indexer". (Plugins -> Macros -> "Install . . ." (cmd-shift M): "Toe Indexer.txt".)

3. Open a footprint in JPEG format, from File -> Open.

4. Press 1 to work with a copy of the original footprint file. A "New Window" dialog comes up; click “OK” to create a new JPEG file called "Temporary." (Don’t press the Return key to create the new file. It deletes the image.) Resize the window as necessary to see the entire footprint on screen.

5. The ImageJ "Log" window opens with instructions to place the medial and lateral ball and heel points. These are based on Webb et al. (2006). Hold the Shift key down while placing them, so that all four are selected when you are done. All four points can be moved individually by dragging them, after they have been placed and before going to the next step. The ImageJ "Results" window opens on the first mouse click and displays the coordinates of each point as it is added. These can be ignored.

6. Press 2. ImageJ will draw the transverse ball and heel lines and the longitudinal axis, in magenta. Then, the image will be rotated so that the longitudinal axis is vertical.

7. ImageJ will draw the anterior toe line (in green) and select it. The "Log" window instructs you to place the anterior toe line. Grab the anterior toe line by the middle handle and move it vertically until it just touches the anterior-most point of the longest toe (or any other toe you desire).

8. Press 3. ImageJ will lock the anterior toe line in position (magenta) and draw the posterior heel line (green). As directed by the "Log" window, drag the line to intersect the posterior-most point of the heel where the edge of the print intersects the longitudinal axis.

9. Press 4. ImageJ will lock the posterior heel line in position (magenta) and draw the medial ball line (magenta) for reference. ImageJ will also select the magnification tool from the Tool Palette. As directed by the "Log" window, click on the region of the medial ball line to zoom in. When sufficient magnification is achieved, choose the point selector tool and, with the Shift key down, place the anterior and posterior ball points as defined by Webb et al. (2006), i.e., mark the most anterior and posterior points that could reasonably be chosen as the most medial projection of the ball.

10. Press 5. ImageJ will draw the metatarso-phalangeal joint line and calculate toe index, which will be displayed in the "Log" window.

11. When you are finished with the footprint, close the file "Temporary", saving it (with its measurement lines) or discarding it. Close the original footprint JPEG without saving it. You are then ready to open a new footprint file and start again.