These images are encoded in a random pattern, and it used to be thought that only computers could detect them. However, in a new paper published on the preprint server arXiv, scientists from Heriot Watt University in Edinburgh, Scotland and Glasgow University found that the human eye itself can perform the required calculations.
Danielle Fajo, a co-author of the study and a professor of physics at heriott-Watt University, said that although the brain can't see them alone, the eyes can somehow detect all the patterns. The most amazing optical illusion (and how it works)
Ghost images are generated in ordinary cameras, and multiple pixels absorb light from a light source (such as the sun) to create images. "Ghost images are basically the opposite: they start with multiple light sources in a predictable array," Faccio told LiveScience. Light is collected by a single point detector, usually called a "bucket".
A simple way to imagine how this works is to consider a lidar that uses a single point laser to scan the scene. The detector captures how the laser light reflects from every point in the scene, and then can be reconstructed into an image.
These visions of 4 and 6 show what the eyes see. Black and white patterns are projected onto the original images of 4 and 6, and the generated reflected light can be processed to display the original images. Researchers once thought that only computers could complete this process, but new research shows that the human eye can at least partially complete it. Facio said, but there is a faster way to get ghost images. Researchers have found that they can project patterns onto the scene instead of scanning the scene with a single light source. The light and pattern reflected by the object can then be measured. The difference between this light pattern and the original projection pattern contains "ghost", and then the computer can extract it from the data by mathematical methods. These images look like gray-scale representations of the original images.
Fajo said that in the calculation of ghost illusion, this method of making ghost images involves two mathematical steps. The first is to combine the original pattern with the pattern displayed after projection on the object. This is achieved by multiplying the original pattern with the light signal emitted by the object and the pattern of each point. Step two, add up the numbers in the whole scene. [1 1 the most beautiful mathematical equation]
"The question we ask ourselves is,' Can the human brain do it?' Fajo said,
The researchers decided to focus on the second half of the calculation and add up all the models. In order to do this, they first projected a chessboard pattern named Adama on the famous photo of Albert Einstein sticking out his tongue. Then, they use a single-pixel detector to collect light patterns and input them into an LED projector.
The LED projector illuminates the Einstein-Hadamard mode on the screen displaying the original Hadamard mode, and basically multiplies the two modes. Step 1: Finish.
The next step is to see what people can see when they look at this sum. The researchers found that when the Einstein-Adama model was projected slowly with a pulse of 1 sec or longer, people only saw the black and white chessboard-there was no ghost. But as the researchers accelerated the prediction, Einstein's silly face appeared. The researchers also experimented with numbers and letters and found that they were recognizable in the "ghost" version.
Fajo said that blacks and whites "will not disappear." They will turn gray, and you really start to see the image in front of you.
Faccio said that click refresh is effective because the refresh rate of human eyes is low. This is no different from the working principle of movies: when the flashing speed of an image on the screen exceeds this refresh rate, the illusion of smooth movement will occur.
"The eyes get information very quickly," Fajo said.
The researchers found that this blinking pattern stayed in the "memory" of the eyes for about 20 milliseconds and gradually disappeared with the passage of time. If the 20-millisecond patterns overlap, the eyes summarize them like a movie, so there is a ghost.
Fajo said that the exciting part of this discovery is that ghost imaging system can be used to study human visual system. The researcher's paper is currently being reviewed in a peer-reviewed journal. The research team's next step is to find out whether the human eye can also observe ghosts, perhaps by multiplying the different inputs of the left and right eyes.
This is an original article about life science.