Background

The "Lincoln Illusion" is one of many illusions which are reliant on averaging out images to remove a significant amount of 'fluff' to show a previously-unseeable image. The 'filler' or 'fluff' in these illusions are scientifically referred to as areas of high spatial frequencies.

There are different variations of this type of illusion, however of the most famous are those that denote Abraham Lincoln. Dali saw these illusions and they inspired him to create an incredible painting of the illusion.

What is the optical illusion supposed to show?

His painting - and related variations of the illusion - depict Abraham Lincoln, the 16th president of the United States, but not at first glance.

How can I make the illusion occur?

Firstly, maximize the image to full size (by clicking either of the thumbnails). At full size, you will see the scene of a lady looking out of a window. Next, and importantly, you will only be able to see the image be replaced with the portrait of the famous individual by squinting and stepping back from the screen. If you cannot see the figure, move further away from the screen until the hidden image comes into reasonable (do not expect perfect) focus.

Images

Along with the main variation, below are two other varieties of the "blurred image illusion".

How does it work?

The general reasoning for the illusion is that the 'fluff' is of a high spatial frequency. Blurring the image removes the amount of noise observed by the 'filler'.