What makes a 3D image? It all boils down to "visual displacement". Let's start with the most important part of viewing the world - the eyes. The human eyes are separated by about 6 centimeters, which means that if you look at an object, both eyes are looking at it from the left and right viewpoints. The left eye will see the left side of the object, while the right eye will see her center or right side. When the object seen by both eyes is imaged on the retina, the impressions of the left and right sides are combined to give the final three-dimensional sensation. This effect of obtaining three-dimensionality is called "visual displacement".
When shooting images, as long as the two cameras simulate the parallax between the left and right eyes, respectively, to shoot two films, and then the two films are simultaneously projected on the screen, the projection of the necessary technical means, so that the audience can only see the left eye image, the right eye can only see the right eye image. Finally, after the two images are superimposed by the brain, we can see the picture with three-dimensional depth. This is what we call 3D images. Here are a few different principles of 3D.
Early black-and-white stereoscopic images: red and green color filter lenses
These glasses, which I'm guessing we've all seen before, were very common when I was a kid. We can try to write on a piece of white paper with a red pen and a green pen, through the red lens, the white paper also becomes red, the eyes can not see the words written by the red pen, but can see the words written by the green pen. And through the green lenses to see the paper of course can not see the green words, can only see the red pen handwriting. According to this principle through the red and green glasses filtering process, each of the two eyes to see, by the two cameras are not quite the same picture, and ultimately the superposition of the two images formed a stereoscopic vision, which is the early stereoscopic film red and green color filter lens technology. This technique was relatively simple to implement and inexpensive.
Early color stereoscopic images: split-image polarized stereoscopic images
This is also a common stereoscopic imaging method, ordinary light is along the wavy route, as people shake a long rope. If you let the light waves through a special lens that allows only a particular kind of vibration of the light waves through, as if the fluctuation of the rope to set up a fence, the result is that the fluctuation of the rope can only pass through the perpendicular direction of the fence, and can not pass through the parallel direction of the fence. This special lens is called a "polarizing lens". The effect of early color stereoscopic films was formed by the polarization of light. Stereoscopic film using a left and a right two cameras at the same time to shoot the same scene, the projection of the use of two projectors, each set of a polarizer, the image of the two polarized light at the same time projected on the screen, the direction of vibration of the two polarized light can be at right angles to each other. The audience to wear special polarized glasses when watching the film, and the left and right two lenses through the vibration direction of the polarized light perpendicular to each other, can pass through the left eye of the polarized light can not pass through the right eye, and can pass through the right eye of the polarized light can not pass through the left eye, in this way, the left eye of the lens allows only the left side of the camera's image through the right eye of the lens allows only the right side of the camera's image through the right side of the image, and finally, color stereoscopic images appeared! The final color stereo image appeared.
The most convenient way to watch: naked eye 3D stereoscopic images
For those who are already nearsighted, wearing a pair of 3D glasses is really very painful, and what is the ideal 3D viewing effect? Definitely the 3D effect can be seen with bare eyes. Japan's Fujifilm has released a digital camera that can take 3D photos and videos. This is the world's first digital camera that does not require the use of specialized glasses, and can enjoy stereoscopic images with the naked eye. The camera has two Fujinon lenses and two CCD sensors. The two lenses on the body of the camera can simultaneously capture two images from two angles with a small difference, and then synthesize the two images through newly developed image processing technology to create a 3D effect. Users do not need to wear special glasses, on the back of the camera 2.8-inch LCD screen can see three-dimensional photos and videos. Anyone who presses the shutter will be able to capture the stereoscopic effect. In addition to the camera's own display, users can view captured 3D photos and videos through a dedicated digital album available at retail. In addition, Fujifilm offers a 3D photo developing business that uses a unique coating technology to control the direction of light propagation and realize a naked-eye 3D effect.
"Naked eye" 3D technology has not matured, but there have been a number of home appliance manufacturers to develop a number of three-dimensional image without glasses can see the television, in addition, scientists are also trying to use holographic imaging technology to achieve three-dimensional effect, the latter has been successfully used in some large-scale activities. And in the theater, the United States Real D company announced that it wants to let the audience take off the 3D glasses in 10 years to watch stereoscopic movies directly, by that time, the audience to watch 3D movies will be more convenient and comfortable.
How 3D images are formed in the brain
The gradual popularization of 3D movies and 3D TVs has not only brought us visual shock, but also a series of problems. We live in a three-dimensional world, it is natural that we should use three-dimensional vision to see the world, the birth of 3D technology, is the product of the high degree of integration of visual needs and technological development. So, how is the 3D image formed in the brain?What is the impact of 3D movies and 3D TV on our body, especially our eyes?
3D is the abbreviation of three-dimensional stereo, which indicates that there are 3 directions of distribution of objects in space, i.e., left and right directions, up and down directions, and front and back directions of objects. When our eyes observe an object, we can see not only the length and height of the object, but also the depth of the object. This is because the viewing angle of our two eyes is different, and this difference is transmitted from the retina to the brain, which can distinguish the front and back distance of the object and produce a sense of three-dimensionality, which is stereoscopic vision.
When we record with photographs, television and movies, we transform the three-dimensional reality into a two-dimensional flat image. If we want to see a stereoscopic image from a flat image, we need to take the same image and create two images based on the difference in the perspective of the two eyes, so that the two eyes can see one image each, and produce stereoscopic sensation through the fusion of the brain. There are three ways to change a flat image into a stereo image, namely eye mode, eyeglasses mode and screen mode.
Eye mode is a naked eye mode. Our eyes are synchronized in the same direction, looking to the left, are turned to the left; looking up, are turned up. There is only one case where the eyes turn in opposite directions, i.e. both eyes can turn inward. This is the role of eye convergence, is adapted to look close and unique function. There is a three-dimensional stereoscopic picture, consisting of a series of repeating patterns, when the eyeballs are highly cohesive, the formation of the "right eye", you see a three-dimensional image. This method can also watch stereoscopic movies, with "eye to eye" to watch side-by-side movie clips of the same content, you can see three images, the middle image is stereoscopic. This mode can only be used for a short period of time and will cause visual fatigue over time.
Eyeglasses mode is through the glasses to make us produce stereoscopic sense, common chromatic aberration method, polarization method and shutter method. Chromatic aberration method is more commonly used in the early stereoscopic films, through the filter, so that both eyes separately see the same object of different colors, producing a sense of three-dimensional. The polarization method is to polarize light in the horizontal and vertical directions through polarizing lenses in each eye to produce a sense of three-dimensionality. The shutter method is to wear shutter-type glasses and control the opening and closing of the glasses, respectively, so that we can see the images of the left and right eyes separately, forming 3D images in the brain. Theaters mostly use the polarized method, while 3D TVs use both polarized and shutter methods.
Screen mode is to give the task of binocular stereoscopic imaging to the screen, is a more advanced naked-eye mode, generally used in TVs, cell phones and game consoles, etc., mainly using parallax barrier technology and columnar lens technology. Both technologies **** the same characteristics, is through the transformation of the screen to separate the visual images of the two eyes, so that the left eye to see the "left-eye image", so that the right eye to see the "right-eye image", through the fusion of the brain, so that we see the 3D image. This is the future direction of 3D TV.
The above three modes are to turn the flat image into a three-dimensional image, and there is a way to watch the three-dimensional image for the holographic mode. Hologram is a three-dimensional three-dimensional object in the form of light, can be expressed in a subtle micro warping, it can be observed from all directions, is a purely three-dimensional mode. It is virtual and can only be seen, not touched. This hologram also exists in life, which is a mirage. This mode is more commonly used in the production of the movie, it can show the real world does not exist scene, enriching people's lives.
Not everyone can see stereoscopic images. Some people suffer from stereo blindness and are unable to see in three dimensions. There are also some people who have abnormal stereoscopic vision, or whose binocular vision is so different that it is difficult to produce stereoscopic vision. It is best for these people not to watch 3D movies and TV.
Some people experience nausea, dizziness, dry and sore eyes, and even acute glaucoma attacks after watching 3D movies. Watching 3D movies itself does not cause harm to the eyes, some people will have nausea and dizziness after watching 3D movies, which may be related to factors such as strong sound and light effects in the theater and the clarity of the film. Dry and sore eyes may be related to the long time watching the screen and less blinking. Acute attack of glaucoma is related to the dark environment of the theater, in the dark environment, the narrow angle of the room are prone to glaucoma, watching ordinary movies in the theater can also occur.
The greater concern is the effect of watching 3D TV on the eye. Most people rarely go to the theater, but more at home to watch TV, from watching 2D TV to watch 3D TV is a great improvement in the quality of life, but people do not know how to choose the dazzling 3D TV. 3D TV is mainly divided into time-sharing mode and spectral mode. Time-sharing mode utilizes active shutter glasses to achieve the 3D effect. The images of the left and right eyes on the TV screen are played in chronological order, with the opening and closing of the glasses, so that the right eye only sees the "right-eye image" and the left eye only sees the "left-eye image", synthesizing 3D vision in the brain. This mode has no effect on the clarity of the image, but due to the rapid change of the left and right eyes to play the image, it will cause flickering. Polarization mode is to put the TV screen with polarized film, so that the light out of the TV is only horizontally and vertically polarized light, and then with polarized glasses, so that the two eyes can see the polarized light in different directions, forming 3D vision in the brain. This mode will have an impact on the clarity of the image due to the compression methods used for the image, such as up and down format, left and right format, or horizontally interlaced format, etc. However, since there is no transformation of the image, it does not flicker, and is also known as a non-flashing 3D TV. Watching 3D TV is different from watching 3D movies in the theater, the sound and indoor lighting can be freely adjusted, and you can walk around freely during the TV watching, so the eye and whole body problems that occur when watching 3D movies may be less likely to occur when watching 3D TV. Some experts analyze that the visual effect of 3D is not exactly the same as the real 3D that we usually see with both eyes, to adapt to this change, more brain fusion power is needed, which can easily lead to headaches; the eyes to adapt to this change, will be over-adjusted, resulting in visual fatigue.
3D movie is to use two adjacent cameras to shoot the "left eye image" and "right eye image", the left and right eyes to see their own images at the same time in order to form a 3D image, a few days ago, 3D TV time-sharing and spectral broadcasting have Inadequate. Ideal 3D TV should be a comprehensive simulation of the human eye stereoscopic vision, we look forward to naked eye 3D TV to solve these problems, which will be the highest realm of artificial stereoscopic vision.
Technology classification
3D display technology can be divided into two categories of glasses and naked eye. Naked eye 3D is mainly used for public business occasions, and in the future will be applied to cell phones and other portable devices. In the home consumer field, whether it is a monitor, projector or TV, are required to use with 3D glasses. Mainstream glasses 3D technology has two main types: non-flash 3D TV way is the closest to our actual feeling of three-dimensionality, the most natural way. As in the movie theater to enjoy the 3D image of the living tiger, able to watch two images at the same time to separate the left image and the right image of the special film affixed to the surface of the 3D TV and glasses. After separating the left and right images through the TV and sending them to the glasses at the same time, the glasses filter the separated left and right images and send them to each eye, and then the brain synthesizes the two images to make people feel the 3D stereoscopic sensation.
Features of non-flash 3D:
Instead, worry about their children too close to the TV and the eye health of the smart parents, prefer to comply with the audio-visual recommended distance I this non-flash 3D. and, because of the use of IPS hard-screen panels so there is no restriction on the left and right viewing angle, regardless of the angle of view is very sharp, no color change phenomenon, and non-flash 3D TV at Any angle can enjoy 3D image.
Superiority of non-flash 3D:
1. No flickering, can reflect the eye very comfortable 3D image. Flicker-free 3D is not powered by electricity, so you can wear your glasses comfortably and feel no flicker at all. So you can enjoy 3D images that are comfortable for your eyes. As you can see from the actual measurement of the flickering level, the data is almost zero, and there is no dizziness.
2. Wide viewing angle, as long as the viewing of non-flashing 3D TV is within the recommended distance, watching at any angle, its picture effect, color expression are not compromised, you can enjoy the perfect shock 3D image in the case of no angle limitations.
3. Enjoy 3D images with lightweight and comfortable glasses. Flashless 3D glasses are lightweight, affordable, and can be used with clip-on glasses to make them comfortable for people who wear glasses.
4. 3D images without overlapping frames. The phenomenon of overlapping images occurs when the right image goes to the left eye or the left image goes to the right eye. The special film used in Flickerless 3D separates the left and right images to create a 3D image, so there is no overlap and you can enjoy seeing the stereoscopic image of a real, live object. By actually measuring the image overlap data, you can see that the overlap data of Flickerless 3D is at a level that is imperceptible to the human eye.
5. High-definition 3D images with no picture drag. Flicker-free 3D is capable of producing 240 3D composite images per second. So in the same amount of time, Flickerless 3D is able to display more picture information and show high definition stereoscopic images without drag.
Relating to the angle of view, in the audio-visual recommended distance to watch the flash 3D is not a problem. For example, there is no problem with viewing 3D TVs within the recommended viewing distance, except for standing, sitting, or watching TV in a very unusual position within one meter. Shutter 3D technology, Active Shutter 3D in English, is used with active shutter 3D glasses. This 3D technology in the TV and projector above the most widely used, relatively more resources, and the image effect is excellent, by many manufacturers to promote and use, but its matching 3D glasses price is higher.
Disadvantages of the shutter type:
1, after wearing glasses, the brightness is reduced more;
2, the frequency of opening and closing of 3D glasses by fluorescent lamps and other luminous effects lead to the opening and closing of the shutter of 3D glasses and the left and right images are not fully synchronized, there will be crosstalk phenomenon, it is recommended to turn off the lights when watching
3, shutter-type 3D glasses are basically in the price of 1,000 yuan, relatively expensive, and need to be matched with a higher price of 3D glasses, the price is relatively high. The price of shutter 3D glasses is around 1000RMB, which is relatively expensive and requires installation of batteries or charging. Color separation method
Currently the most popular application is the color separation method, which is the use of different colors of the image overlap, and then the use of red and blue glasses to separate the overlapping images filtered to achieve the depth of field, the benefits of the glasses are inexpensive, and the technical threshold is low, the equipment requirements are low, the overall cost is low, but the effect is the most common. Disadvantage: is that the image fails to full-color display.
Light division (polarization) method
The production of 3D stereoscopic film, which is more widely used is the light division method (or polarization method). It uses two polarizing axes into each other 90 degrees of polarizer, respectively, placed in front of the two projector lenses, and then overlap the image to achieve 3D stereoscopic effect. For glasses, polarized lenses are also used. However, the cost of filming and production and hardware equipment is relatively high. Disadvantage: The image needs to be viewed horizontally with the glasses.
Light division method
Most 3D movie theaters use light division 3D technology.
Time division method
Time division is the most effective way. It utilizes the time difference to achieve the 3D stereoscopic effect. It uses a high-frequency monitor, through the frequent frequency to quickly switch between left and right images; at the same time, the glasses will also be left and right side of the lens will become visible and closed state, left and right repeatedly; so that the overlapping images in the monitor were transmitted to the left and right eyes, through the visual residual, so that the brain calculates a 3D stereoscopic image. Advantages: Full-color display, no positional problems in viewing the image. 3D image technology has a wide range of applications, including: 3D film post-production, 3D animation production, digital city construction, promotional films, virtual simulation, phantom imaging, stereoscopic theater construction, 3D game production, exhibition, large-scale touring activities, 3D teaching, 3D medical imaging and other fields.