I always was a big fan of M.C.Escher and his recursive and impossible pictures. When I saw the first escheresque photograph I could not resist to search the web and find out how it is done. A few days ago I rediscovered the technique of the Droste effect. A Droste effect picture is a picture within a picture within a picture within a picture… a neverending spiral.

This tutorial is based on the tutorial by Josh Sommers, which is a little outdated so I wrote a short guide on how to do it with current versions of the tools. As the original this version is directed at Windows users.

What you will need for this tutorial:

• A working installation of GIMP version 2.6 or newer. Unfortunately MathMap does not work on the new releases of GIMP (as of 2012-06-22).
• A copy of the MathMap plugin version 1.3.5
• Obviously a picture! To make things easy, your picture should be square and the area to be left out should be in the middle. I chose a mirror shot. Feel free to use the picture from Flickr for your personal proof of concept.

Step 1: Preparing the picture

What you need for this particular example is a picture “with a hole inside”. I prefer the border to be soft and the inside will have to be transparent.

1. Select the area to be made transparent with the circle tool (if your area is rectangular you will have to adapt this part to your needs.
2. Feather the selection using select>feather from the menu.
3. Invert the selection and cut it [Ctrl]+[X].
4. The cut selection has to be added into a new transparent layer.
5. Anchor the selection to the layer.
6. “Unselect” the selection.
7. You can now turn off the layer with the circular hole or delete it. We won’t need it any more.

Step 2: Droste effect with MathMap

1. Start the Droste plugin with General>MathMap>Map>Droste and you will see something like the following.
2. Change to the Tab marked User Values.
3. Adjust the inner and outer radius until the picture looks OK.
4. Zoom in to fill the frame, rotate it a little bit and check the box AutoSetPeriodicity.
5. Press OK.

Congratulations. You just created your first Droste.

So this was a simple one. Now you can go on and create something more difficult. Take a picture of yourself with a board in your hand and make the picture rectangular. All you need to do is play with the settings. Or maybe you ask someone else to hold a box…