Producing a stippled image with Gimp

To produce TSP art of an image, you will first want to generate a stippled rendition of the image. The easiest way to do this is with a stippling extension for your image editor of choice. If, however, your image editor lacks such an extension then you will need to find another means of producing stippled renditions of your images. This document explains how to do so using the GNU Image Manipulation Program, Gimp. Gimp may be downloaded from

www.gimp.org

In this discussion, the screen shots and results were produced using version 2.6 of Gimp running on a Mac.

In what follows, step by step directions are provided. The basic plan of attack will be to

1. Change the image to grayscale
2. Make the image "washed out"
3. Dither the image to black and white (1 bit color depth)

If the final step produces too many stipple points, then before the second step, first reduce the image's dimensions to 50 or 25% of its original size.

Now for the detailed steps. [Note that on a Mac, Gimp's menu does not appear along the top of your screen but rather along the top of the GImp window itself.]

1. Open your image file in Gimp
After launching Gimp, open your image file using the "Open..." item under the "File" menu item like so

[[1]]

A file selection dialog will appear. Navigate to the file containing your image and click the "Open" button. Gimp will likely toss up a question like the one shown below. You can click "Cancel" or "Assign". For our purposes, there should be no consequences from either choice.

[[2]]

Once the image file is opened, you should be presented with a new Gimp window displaying your image,

[[3]]

2. Convert your image to grayscale
From the menu bar in the window with your opened image file, select the "Image" menu item. From that drop down menu, select the "Mode..." item and then "Grayscale".

[[4]]

Once you've done that, your image should then appear in grayscale.

[[5]]

3. Wash out the image
Now, from the "Colors" drop down menu, select the "Levels" item.

[[6]]

That will bring up a new window with the title "Adjust Color Levels". In that window, you want to set the "All Channels" output level to a large number in the range 180 to 245. You can do that by entering a numeric value in the circled field or by sliding the triangular slider indicated with the red arrow.

[[7]]

The larger the value, the more washed out the resulting image.  The more washed out the image, the fewer the number of resulting stipple points in the later steps.  The next image, shows the result of adjusting the output level to 200.

[[8]]

--to be continued--