# What's new

## Infinite photos

By David, 17 February 2016 Activity

Take a photo of your screen.

Take a photo of a photo of a photo. It’s an infinite photo-ception!

### You will need

• Digital camera
• Computer

### What to do

1. Take a photo of your computer screen.
2. Copy the photo onto your computer.

Open the picture several times on your computer.

3. Open several copies of the image in different windows and spread them out over your screen.
4. Take a photo of your screen, and put the new file on your computer.
5. Without moving or resizing the windows, change the image in each window to the new photo.
6. Take a photo of your screen and put the new file on your computer.
7. Keep repeating this process for as long as you like. Enjoy the weird patterns!

### What’s happening?

Keep repeating, and enjoy the patterns!

After only a few loops through this process, you’ll find you have a very large number of little pictures of your screen.

If you have three windows on your screen, then each of those three images will have three smaller screens in them, and each of those three will have three in them. Each layer has three times more images than the last, which means the total number of images goes up very quickly. The type of repetition you’re observing is one that could theoretically go on forever, and it’s called the Droste effect.

Notice the patterns that appear in your photos. Depending on your screen and your camera, the images might get lighter or darker as they get smaller and smaller. If your screen is very bright, then each time you photograph it, the picture may appear a little bit brighter. When you take a photo of the screen again, the lighter windows may appear brighter again. After several rounds of taking photos, the very small images may be too bright to see any details. If your screen is dark, then the opposite may happen, and your images may get darker and darker as they get smaller and smaller.

### Real-life maths

Each image of the screen has smaller images of the screen in it. This means the whole screen looks similar to a small part of the screen. Mathematicians call shapes like these ‘self-similar’ shapes. Many shapes are self-similar – a large tree branch is made of smaller branches, and they are made of even smaller branches. Very self-similar shapes are called ‘fractals’.

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