3D images and videos to watch and watch health exploration
With regard to 3D stereoscopic image viewing and health research, it is of great significance that 3D display devices are becoming mainstream today. What kind of 3D stereoscopic image is correct and healthy, how to view 3D images is more suitable, how to solve the generation of unhealthy stereoscopic vision, etc. are all worthy of our consideration. This article is a summary and summary of the speech of Lu Xiaofen, director of the China Stereoscopic Industry Alliance Health Guidance Committee, at the 9th China International 3D Stereoscopic Video Forum, especially for the definition of healthy and unhealthy stereo vision, the main non-healthy stereo vision. Factors, in-depth analysis of the causes and solutions of unhealthy stereo vision, so that more audio-visual enthusiasts can master the relationship between 3D stereoscopic viewing and health, making 3D viewing healthier.
Reasons for promoting healthy stereoscopic images On the New Year's Day in 2012, China's first 3D TV trial channel was officially broadcast. The 2012 Spring Festival officially launched, CCTV will also achieve a full broadcast of the London Olympics 3D signal. The launch of the 3D test channel completely activated the 3D video content production and operation chain, opening a new era of 3D. At the same time, the extensive influence of 3D TV has also rapidly spread to the mobile and Internet terminals, which has led to the vigorous development of China's entire 3D industry.
People are amazed by the visual magic brought by the three-dimensional image, and the healthy stereoscopic effect makes the mind and body extremely happy. But at the same time, some unhealthy ways make people's visual nerves feel uncomfortable, which makes people have great confusion and doubt about the development prospects of stereo vision products. Welcome to China Home Theater Network !
Below, we try to theoretically clarify the mechanism of unhealthy stereoscopic images based on the phenomena produced by existing stereo products, so that the industry develops along a healthy and correct path. Human beings are in the initial stage of the popularization of stereoscopic images. Mastering the correct theory is of great significance to the development of the stereoscopic vision industry.
All the animals on the earth are two eyes, which is the great creation of nature for the needs of stereo vision. After millions of years of living habits, the human eye and the visual nervous system have adapted to the current viewing habits. That is, the image seen by the viewer's eyes is a synchronous image corresponding to the object, that is, the left eye sees the left image and the right eye sees the right image, and both eyes simultaneously see a stereoscopic image. Correctly restoring the state of the human eye actually viewed is the basic principle of healthy stereoscopic video. Violation of this principle can lead to incompatible reactions of the brain's nervous system, such as dizziness and nausea. The purpose of human inventing stereoscopic images is to provide a true visual restoration, giving people a sense of physical and mental enjoyment. Uncomfortable stereograms can cause people to be extremely disgusted with stereoscopic products. Therefore, letting such situations develop is extremely harmful to the development of the 3D industry.
Definition of healthy and unhealthy stereo vision
All stereo images consistent with normal viewing of the human eye are correct.
All stereo images that are inconsistent with the normal viewing of the eyes of the person are errors.
Several main factors of unhealthy stereo vision
The left and right images do not match.
The wrong image causes the human eye to be out of sight.
Left and right image crosstalk.
The left and right images are interchanged.
The erroneous vision caused by the close-up map.
Causes and solutions for unhealthy stereo vision
1. Inconsistent caused by inconsistent stereoscopic images of left and right images:
The current three-dimensional video in the world is mainly time-division (switch glasses) and optical split (polarized glasses). What are the advantages and disadvantages of each of these two methods? Which one has a greater impact on healthy 3D? The following will be analyzed one by one.
The left x and right x are fully synchronized when shooting, and they need to be fully synchronized during playback. At this point, there will be no problem with the eyes. If the left 1 and the right 1 are completely synchronized during shooting, they will not be synchronized during playback, and an abnormal situation will occur.
When shooting a dynamic object, the camera often moves the object for a long distance in less than one second. At this time, the position of the object in each frame before and after the same eye changes significantly. Please note the left 1 and left 2, left 2 and left 3, left 3 and left 4, left 4 and left 5 and right 1 and right 2, right 2 and right 3, right 3 and right 4, right 4 in the following screens. With the right 5. There is a significant change in the size and position of objects in each frame of the image between them.
The stereoscopic principle of the time-division (shutter-type glasses) is to use the visual residual features of the human eye to sequentially enter the left and right images into the left and right eyes to achieve a stereoscopic image.
The first frame in the time division mode is assigned to the left eye for viewing, and the second frame is assigned to the right eye for viewing. At this time, stereoscopic errors do not occur, but when entering the second frame and the third frame image, serious occurrence occurs. Visual error! Since the human eye has visual residual phenomenon, the right eye sees the first image taken by the right camera, and the left eye sees the second image taken by the left camera. Because the objects in the two images are too different, people The eyes will feel quite uncomfortable.
The time-division stereo TV and the time-division stereo projector can realize stereoscopic view of 1080p full-pixel, which is its advantage, so it is recommended that users use the time-division stereo mode when viewing static images. The time-division stereo mode is prone to unsynchronization when watching motion pictures. At present, the stereo projectors used in most stereoscopic theaters are time-divided, which is the main cause of dizziness. Why is there so many people in the "Avatar" stereoscopic movie say dizziness, the reason is here. This problem can be completely avoided if the time-division stereo image can be reassigned to fully synchronized playback during playback, or polarized glasses can be used to achieve full synchronization of stereoscopic movies.
At present, the optically-divided horizontally-interpreted TV sets (commonly known as non-flashing) can only realize 1920×540 pixel stereograms, which is its shortcoming, but the full synchronization of the left and right eyes is its advantage, which can be comfortably viewed without dizziness. Stereo movie.
The dual projector stereo projection method is still the most comfortable and highest pixel stereo display method.
In addition to the insurmountable causes caused by the time-division stereo method, there are other causes of human error:
Causes of shooting: The two lens shutters are out of sync, the aperture is inconsistent, and the focus resolution is inconsistent.
Causes of editing: high and low image errors of left and right images, misalignment of front and rear frames, and different brightness of left and right images.
Causes of the screening: left and right image position error, front and rear frame misalignment, and different brightness and darkness of the left and right images.
Therefore, industry stereoscopic video standards and testing institutions should be established to prevent false stereoscopic sources from entering the market.
2, the wrongly edited stereo image leads to the human eye line of sight outside the Chinese home theater network welcome you!
When the eye is looking forward, as the object is near to far, the line of sight of both eyes is gradually changed from inside to parallel. Viewing infinity objects such as the sun's eyes is parallel. If a person's eyes are outwardly inclined, there are only two possibilities: 1. The eyes are sick. 2. Watching the wrong perspective.
Double-eye line of sight
Therefore, when making a stereoscopic film, the farthest scene in the left and right images should not exceed 65 mm when the film is enlarged to the cinema screen 10 meters wide. Otherwise, the stereogram will force the eyes to be out of the way, causing the eyes to be uncomfortable.
3, left and right image cross stitch
One eye sees the image that should be seen and also sees another image with a lighter color. This is the left and right image crosstalk, which reduces the stereoscopic effect and causes visual discomfort.
Left and right eye image series
This reason is mainly due to the following aspects:
The alignment between the polarized screen of the optical sub-television and the pixel is not accurate.
Polarized glasses have poor polarization properties.
The time-division TV has insufficient liquid crystal response speed and residual image.
The switching performance of the LCD glasses is not good.
4, left and right image interchange
When the left eye sees the right image and the right eye sees the left image, there will be an anti-stereoscopic phenomenon, that is, the distant scene ran close, and the nearby scene ran to a distant place. This abnormality comes from editing errors, playback errors, or inconsistencies in stereoscopic standards.
Recommendation: When establishing industry standards, the top and bottom views are determined as top left and right. The playback order is first left and right. The left and right identification codes are added during image editing, and the left and right images can be recognized at any time during playback to prevent the phenomenon of anti-stereoscopic.
5, the background caused by the close-range image representation can not be merged
When people watch close-up scenes, distant scenes will be blurred. When watching a distant scene, the close-up scene will be blurred. This is in line with the actual situation of people in life. The method of expressing close-range scenes can cause great problems if applied to stereoscopic movies. If you look at an object that reaches about 1 meter, the focus of the eyes is clear, and the separation of the left and right scenes in the distance is too large, and may be far more than 65 mm on the large screen.
Recommendation: In general, the distance between the binocular converger (image overlay) and the screen (center layer) should not be too far. The background scene can be removed to a blank background when needed. When the standard focal length lens is normally shot, the distance between the two lenses is about 65 mm (60-70 mm), and the angle between the lenses when the long focal length lens is taken at a long distance is 1-3 degrees.
Summary: Stereoscopic video that violates the visual principle is like a fake drug. It is a harm to the human body. Its manufacture, sale, and broadcasting are crimes of different degrees. Now this crime is like a crime in the primitive society, and it is a kind of law without supervision. In the case of crime, no major liability is required. However, this has caused people's bad influence on stereoscopic movies and stereoscopic TVs. "Seeing dizziness" has become synonymous with stereoscopic video. We must pay attention to the relationship between 3D video viewing and health, and also strengthen the production and monitoring of stereoscopic video works, and promote the development of the entire 3D industry.
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