Playback of 3D Video
There are two conditions in which the human eye produces three-dimensional effects:
1. Need to left and right eye two images, these two images are different, with the correct parallax;
2. Into the left and right eye of the image to be completely separated, left-hand image into the eye, right image into the eye.
The first is the requirements of the 3D video source, the video source must include two video, both the relationship between the two video, and there are differences. They are two videos produced at the same time, in the same scene as the same 3D camera (with two camera shots, with two lens distances close to the human eye pupil distance). These two videos are similar and can be used to design compression algorithms to reduce the amount of data, and later learn 3D video capture and storage.
The second is the requirement for 3D playback equipment. How to make the left and right to see different videos, is the core of the problem. At present, 3D technology can be divided into two categories: open-hole and glasses-type. Glasses-free 3D viewers do not have 3D glasses, rely on the front of the display lens array or barrier fence to separate the left and right eye video, the open-hole 3D technology is currently used in commercial display (in the future will be applied to display devices such as mobile phones) to the viewer's position is very strong correlation. Glasses-type 3D Although the addition of an auxiliary equipment, but simplifies the display, playback equipment on the difficulty, so in the TV, film and other consumer market has been widely used. This article mainly introduces this 3D method.
Glasses 3D subdivision for chromatic aberration, shutter type and polarizing type (also called Color Division method, Time Division method, Light Division method) three kinds.
A. Color-Difference Color separations
Chromatic aberration 3D display can be called color-separation stereoscopic imaging technology, is the left and right two-way video in two different colors (such as red-blue, red-green, red-green and other two colors) displayed in the same frame, with the naked eye will appear blurred red and blue ghosting, and through the red and blue glasses to see the effect is, Red or near-red spectra can only be passed through red lenses, blue or near-blue spectra only through blue lenses, thus separating the left and right eye video. The red and blue videos that go into the left and right eye overlap in the brain to show a 3D stereoscopic effect. Since all the points are made of red and blue two base tones, so the screen color is serious, this way the 3D effect is poor, but its glasses low cost, in some pictures of the 3D display field has applications, in the TV, film field applications are not many.
B. Shutter-time sharing
Shutter-type 3D lens is able to control the opening and closing of the two windows, in the same projector quickly alternately play the left and right eye screen, through the synchronization of the glasses and open and close function, in the left screen, left glasses turned off, the viewer left eye to see the left screen, the right eye nothing to see (lens in the black screen state). The same turn over, right to see the right picture, the left eye is not the picture, so let the eyes and left side respectively saw the respective picture, fast staggered display, through the visual temporary stay, resulting in stereoscopic effect. The shutter-type 3D is mainly achieved by increasing the refresh rate of the display device, and then displaying the opening and closing of two lenses of 3D glasses through infrared signal between the device and the glasses. As the left and right eye video in the time, in turn, is equal to the frame rate reduced by half, in order to meet the visual persistence principle, need to improve the refresh rate, so that the lower half of the frame rate also meet the refresh rate of more than 25Hz. Before the display device refresh rate of less than 60Hz, shutter-type 3D is no application basis, and the current LCD TV refresh rate of 120Hz or more than the frame rate, so that the shutter-type 3D can be widely used. The current mainstream TV manufacturers have shutter-type 3D TV products.
The advantage of shutter-style 3D is the full frame lossless of picture quality, while the visual angle is good, so the display device can import this technology as long as the refresh frequency is increased. Its disadvantage is 1. Low brightness, because every time there is a black screen, although you can increase the brightness of the display to reduce the disadvantage, but still have an impact; 2. Shutter glasses are now made of liquid crystal molecular materials, transparent and opaque two states, high cost, weight heavier, long time wearing uncomfortable, and need battery power; 3. By the Fast The principle of door-type 3D technology determines that when there are light sources around, the screen inevitably flashes, long-time viewing will cause human eye fatigue; 4. The shutter switch and left and right images are not fully synchronized when crosstalk occurs, resulting in blurred images.
C. Polarized/non-flashing 3D light-splitting
Polarized 3D is the use of light with the "vibration direction" principle to decompose the original image, the image is divided into two groups of vertical and horizontal polarization by polarizer, and then 3D glasses are polarized lenses with different polarization direction, so that the right and left eye can receive two sets of images, and then through the brain synthesis of stereoscopic images.
Polarization-type 3D display technology has been used for IMAX. Two projectors show the video of the left and right eye respectively, the two projector before each installed a opposite polarizer, its role is equivalent to the polarizer, from the projector light through the polarizer, it became polarized, about two projectors before the polarizer polarization direction perpendicular to each other, resulting in the polarization direction of the two polarized light is also perpendicular to each other , the two beams of polarized light projected onto the screen (requiring two-point-to-point completely consistent projection onto the same screen) and then reflected to the audience, the direction of the polarized light is not changed, the audience use the polarized glasses corresponding to the polarization of the view, that is, the left eye can only see the picture of the left machine, the right eye can only This will see the stereoscopic image, this is the principle of IMAX. There is also a single machine alternately show the left and right eye video, the polarization direction of the polarizer before the lens changes with the left and right eye video. At present, the common 3D films on the market are polarized, it is equipped with polarized 3D glasses, the price is also very cheap.
Polarization-type 3D TV mainly relies on the front of the LCD panel polarization film, the TV display is divided into angular polarized light, the viewer by wearing the right and left eyes of different polarization direction of the polarized glasses to filter the right and left eye of different polarized images, and ultimately by the brain to synthesize 3D images. The polarization film is generally transverse, similar to the interlaced scanning mode, and the odd-even line has different polarization direction.
The TV processing system displays the image of the left eye to the odd line, the right eye image to the even line (which may be odd and even in turn), so that through the polarized glasses is an odd line of the image into the left eye, even line of the image into the right eye, so that the separation of the eyes and left eye video purposes. But the left and right eye images are only half the original image in vertical resolution.
The advantage of polarization-type 3D is that both eyes look at the same time, there will be no flicker of feeling, three-dimensional more natural. At the same time glasses simple cheap, light weight. The disadvantage is that because two images of the left and right eye are presented at the same time in the display panel, it is necessary to provide an image with only half the resolution of the display panel, respectively, to the left eye and the starboard eye by row staggered or staggered columns.
Shutter-type and polarized two 3D TV modes compete with each other, and in the current market, there are a lot of two ways, TV manufacturers high School low product line basically support both methods.
The above is the output work of the display device in order to let the left and right see different video. For the display system, you also need to know where the left and right eye video data is. The simplest way is to give a two-way stream, but this way the amount of data is too large and incompatible with the existing display system (regardless of the image resolution, the existing system generally only support one data input);
This requires the use of some compromise, the left and right eye video data stored in the same frame. The 3D Blu-ray standard is defined in the form of frame encapsulation, first the entire frame of the left eye data and then the 45 pixel high partition, followed by the full frame of the right eye data. A 1920x1080p video that decodes the left and right eye video frame data is 1920x (1080+45+1080). In addition there are common left and right formats, horizontal resolution halved, right and left eye together or 1920x1080, each eye is 960x1080, or up and down format, vertical resolution halved, each eye 1920x540. or checkerboard format.
The display device must resolve the 3D frame format correctly, otherwise the view will be a mess. For example, in the normal TV state to open a 3D program source, it is likely to see a picture of the left and right split screen, which is the display device decoding the 3D frame, but also in accordance with the 2D frame output results, this time need to display device 3D display settings, set to the left and right format, This is what the naked eye will see is a blurred image with a ghosting, with 3D glasses, stereoscopic effect can be revealed.
Shutter-type in the time of the left and right eye, in the space of the eye video can be achieved full height wide. Polarization is spatially divided by the left and right eye, so its resolution is always one dimension is halved and the resolution is reduced. For the left and right half-width or upper and lower half-height 3D source, in the shutter 3D display, do not meet the full HD display, but because the human eye is more sensitive to the vertical direction of image loss, so half-width ratio of the upper and lower half high makes people feel better.
Polarized 3D is generally used in line interleaving (similar to 1080i) per frame 1920x540, exactly corresponding to the upper and lower half high format, so in the polarized 3D TV upper and lower half high format better.
3D Equipment Choose the shutter or polarization, image format choose left or right or down? This time gives you the ultimate answer!
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Future trend must see 3D TV display technology full analysis
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Polarized Active Shutter Two 3D technology Ultimate contrast test
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Playback of 3D Video
