My midterm project was a visual illusion that takes advantage of the limits of human perception. By creating videos that flash through a deck of shuffled cards showing one frame per card, the typical viewer can’t pick out a single card, which is shown for only 4 milliseconds. A card shown for 2-3 frames is visible by some viewers, and 4 frames is sufficient to be seen by the majority of viewers.
This trick is inspired by a trick popularized in the movie Now You See Me, featuring Jesse Eisenberg. Here is a clip of him performing the trick in the movie.
I experimented with many possible variants of the video to ensure that the video seemed smooth and homogeneous, while still maintaining a high success rate for the illusion. This involved showing the desired card for various numbers of frames and experimenting with blur to make the non-target cards less easily detected.
The video from Now You See Me had extreme blurring on all cards except the 7 of Diamonds, which was fine considering the dynamic action of riffling through cards. Because my video simply showed pictures of cards, there was no believable reason why cards in the middle of the video should be heavily blurred.
My final video involved a combination of longer exposure to the target card and blurring of non-target cards. The cards became steadily more blurred over the first half-second of the video, from zero blur to a 16 pixel Gaussian blur. About two thirds of the way through the video, my desired card was shown for four frames. The first and fourth frames were blurred (20px Gaussian), and the middle two frames were entirely unblurred. This allowed for clear viewing of the card for two full frames. This also still gave the impression that the scene was constantly shifting, as the jump from the blurred card to the unblurred card was mistaken for a jump to a completely different card. In contrast, simply showing the desired card for four frames was always recognized as a “blip” in the video by viewers.
Here is the video of the final trick performed (courtesy of Jon Bobrow).