High definition camera standard

Lead: With the development of digital technology, high-definition cameras are digital cameras that can shoot high-quality and high-definition images, and the images can reach the 720-line progressive scanning mode with the resolution of 1280*720, or the 1080 interlaced scanning mode with the resolution of1920 */kloc-0. So what is the standard for high-definition cameras? What are the characteristics of high-definition cameras? Let's take a look at it next.

High definition camera standard

Borrowing the broadcast standard: a camera with the resolution of 1080p and corresponding transmission channels can form a set of high-definition monitoring system. At present, there is no universal HD standard in the security video surveillance industry. Some manufacturers think that the image reaching D 1 is HD, and some manufacturers think that it is HD if it exceeds 480 lines. Opinions vary.

Here you can look at the national standard of DVR. In 2006, the national standard GB 208 15-2006 issued by the General Administration of Quality Supervision, Inspection and Quarantine stipulated that DVR can be divided into Class A (resolution not less than 4CIF) and Class B (resolution less than 4CIF). According to the evaluation standards of the above manufacturers, the A-class products in DVR are high definition products, and the B-class products are general products, that is, 4CIF (resolution 704×576) is high definition, and CIF (resolution 352×288) is ordinary definition. With the progress of science and technology, "high definition" technology will be introduced into the field of video surveillance, and the high definition standard of video surveillance industry will be continuously improved.

Characteristics of high-definition camera

1, high image definition

High-definition IP network camera, using 5 million pixel progressive scanning CMOS image sensor, can achieve full real-time broadcast quality of 720P( 1280*720 resolution)/1080p (1920 *1080 resolution), which is much higher than the traditional CCD analog camera.

2, color reproduction is realistic

The video capture and compression chip used in the system is a world-famous brand from the United States, and it is also a provider of professional broadcast video capture chips such as Sony Panasonic. Color display is comparable to the color reproduction of professional 3CCD camera, and it has absolute advantages in image color fidelity, color information processing, wide dynamic range and system noise reduction.

3. Long service life of the system

Because the system adopts CMOS image sensor, the power consumption and heat generation of the camera are low. The stability is also much higher than that of traditional analog cameras. At the same time, because the components are relatively simple, the failure rate is relatively low. POE power supply will be supported, and the power supply will be directly through the network cable, which solves the problem of on-site power supply.

4. The system has strong environmental adaptability.

The system has an adaptive intelligent adjustment mode, which can automatically adjust the camera's aperture, gain, noise reduction and other parameters according to different light environments, and always maintain the most perfect picture effect. Because the system realizes the full digitalization of monitoring from acquisition to storage, the traditional phenomenon that the camera is directly affected by light changes will no longer exist. At the same time, the common video signal interference in line transmission will also disappear completely.

Advantages of HD camera

The traffic monitoring system provides an intuitive scene image for the command center. Usually, more than 70% of people's information comes from vision. Commanders and relevant leaders can fully understand the actual traffic situation and public security situation of major roads and key traffic intersections through large screens, computers and other display devices, and provide first-hand information for decision makers.

When an emergency happens, you can watch the event process in real time on the big screen, and you can also play back videos and so on. Therefore, the performance of the front camera and the quality of its image signal will directly affect the effect of real-time video recording and real-time monitoring. Under the framework of high-definition monitoring technology, a high-definition camera can achieve the monitoring effect of several ordinary cameras, and the monitoring coverage is getting wider and wider. And can effectively reduce the system scale and avoid complicated video images, control and power transmission lines.

In addition, the use of high-definition cameras can greatly reduce the configuration of front-end and back-end equipment, thus reducing the overall construction cost. Therefore, high-definition monitoring technology will promote the development of video monitoring system to intensive and efficient direction. Advanced photoreceptors are used to make the image details clearer and more delicate. Progressive scanning can provide better image quality, effectively solve the comb blur phenomenon caused by interlaced scanning, and also provide favorable preconditions for intelligent analysis and other applications, which is of great significance for intelligent analysis applications such as license plate and face recognition.

Basic knowledge of film and television photography

1, lens push-pull skills

The push-pull technology of lens is a set of opposite technologies, and one of them can often be used to realize the other in nonlinear editing. Pushing the lens is equivalent to walking directly along the straight line of the object to see the object, while pulling the lens means that the camera keeps leaving the object. Of course, both of these technologies can be realized through a zoom lens. The role of push lens in shooting focuses on highlighting important people or objects in later films, which is the most common role of push lens. It can make the audience's line of sight gradually close to the subject, and gradually guide the audience's observation from the whole to the part. In the process of pushing the ground, the content contained in the picture gradually decreases, that is to say, the movement of the lens abandons the superfluous things in the picture, highlights the key points and leads the audience's attention to a certain part.

This effect can also be achieved by using a zoom lens, that is, gradually moving from a short focal length to a long focal length, so that the audience can see the subtle parts of the object and highlight the key to express the content. Pushing the lens can also show a huge space.

Pulling a lens is just the opposite of pushing it. This means that the camera keeps moving away from the subject, and you can also shoot with a zoom lens (gradually adjust from a long focal length to a short focal length). It has two functions, one is to show the position of the protagonist or scenery in the environment. The lens moves backward and gradually expands the field of vision, which can reflect the relationship between the part and the whole in the same lens. Second, it is also necessary for the connection between shots. For example, the former is a close-up shot of one scene and the latter is a shot of another scene, so it is much more natural for the two shots to connect like this.

The push-pull effect of lens is different from zoom. For example, in the technique of pushing the lens, the method of using zoom lens is equivalent to magnifying a part of the original subject. The effect on the screen is that the relative position of the scene remains unchanged, and the scene remains unchanged, but the original picture is enlarged. It is more suitable to use zoom lens to achieve this lens effect when the main body of the shooting scene has not changed and it is required to approach the object at any speed without continuous jitter. Moving the lens to push the lens is equivalent to observing close to the subject. The effect in the picture is that the objects in the scene move backwards and the size of the scene changes. This is very effective when shooting narrow corridors or indoor scenery. There is a clear difference between moving the camera and using the zoom lens to achieve the push-pull effect of the lens, so we need to have a clear understanding of the shooting concept and cannot simply replace the two.

2, shaking the lens skills

This lens technology was pioneered by French photographer Dixon in 1896, and also developed according to people's visual habits. When using the panning technology, the position of the camera does not move, and the lens changes the shooting direction, which is very similar to when we stand still and turn our heads to see things.

There are several types of panning lenses, which can swing left and right, up and down, tilt or mix with moving lenses. The function of panning is to let the audience show the scenes to be shown one by one. Slow panning skills can also cause prolonged space-time effects and give people an impression.

Shake the lens to show the content from beginning to end in one go, so it is required that the purpose of the lens picture at the beginning and end of the film is clear, and a series of processes between the two lenses should also be the content to be shown. Moving the telephoto lens away from the subject will also cause lateral movement or lifting.

The movement speed of the pan/tilt lens must be uniform. When it starts, it will stagnate for a moment, then gradually accelerate, decelerate at a uniform speed, and then stagnate, and the left picture will be slow.

3, the skills of moving the lens

This lens technology was inspired by 1896, when French photographer Promio was on a yacht in Venice. He envisioned "shooting with a moving film camera, so that stationary objects can also move", so he pioneered the "side lens" in the film, that is, putting the camera on a moving car and shooting to one side of the track.

The purpose of this kind of lens is to show the spatial relationship between people and things, people and things in the scene, or to show something coherently. There are similarities between moving lens and shaking lens, both of which are to show the relationship between subject and companion in the scene, but the visual effect on the screen is completely different. Pan-tilt lens means that the position of the camera is fixed, and the shooting angle and the angle of the object are changing, which is suitable for shooting distant objects. However, the moving lens is different, that is, the shooting angle is unchanged, the camera itself moves, and the angle with the object is unchanged, which is suitable for shooting objects and subjects with close distance.

Mobile phone photography is mostly dynamic composition. When the subject presents a static effect, the camera moves to make the scene pass through the picture in turn, resulting in a visual effect of patrol or display; When the subject is dynamic, the camera moves with it, forming a visual effect of following. It can also create a specific mood and atmosphere.

When moving the lens, you can use other moving tools, such as airplanes in high-altitude photography, trains and cars in the wilderness, in addition to the moving car laid on the track. Its movement can be roughly divided into lateral movement and deep movement according to the direction of movement. When the camera is not moving, changing the focal length or moving the subject in the background can also achieve the effect of moving the lens.

4. Follow the camera skills

Refers to the camera following moving objects, such as pushing, pulling, swinging, lifting, rotating, etc. Follow-up keeps the dynamic subject in the picture unchanged, while the foreground and background may be constantly changing. This shooting technique can not only highlight the subject in motion, but also explain the direction, speed and posture of the object and its relationship with the environment, so as to keep the movement of the object coherent and help to express the mental outlook of the characters in the dynamic.

5, lifting lens

This lens technique refers to the picture taken by the camera moving up and down, and it is a method to express the scene from multiple viewpoints. Its changing methods include vertical direction, oblique lifting and irregular lifting. Changing the camera's height and tilt angle will bring rich visual experience to the audience. If skillfully used, it can enhance the illusion of spatial depth and produce a sense of height. If the lifting lens moves properly in speed and rhythm, it can creatively show the emotional appeal of a plot. It is often used to express the development law of events or the subjective emotions of the subject moving up and down in the scene. If we can combine the skills of other lenses in actual shooting, we can show changeable visual effects.

6, lens throwing skills

This technology requires a higher cameraman, that is, after a picture is shot, the camera quickly "shakes" in another direction, thus changing the picture of the camera into another content, and the content shot in the shaking process becomes blurred. This is also very similar to people's visual habits, much like we suddenly turn our heads to another thing when observing things, which can emphasize the transformation of space and the juxtaposition of scenes in different scenes at the same time.

Another way to throw a shot is to shoot a moving image shot thrown in the required direction, and then edit it between the front and back shots.

The effect of camera swing is an extremely fast rhythm, which can cause a sudden transition. When editing, the direction, speed and speed of throwing and the length of the process should be adapted to the movements of the front and rear lenses and their direction and speed.

Step 7 rotate the lens

There are several common shooting methods for pictures with rotating subject or background: 1. Rotating shooting along the elevation angle of the lens optical axis; Second, the camera shakes 360 degrees quickly; Third, the subject and the photographer rotate 360 degrees on almost one axis; 4. When the camera is stationary, the image or photo on the film or tape is rotated, inverted or turned to any angle of the 360-degree circle for shooting, and it can move clockwise or counterclockwise. In addition, you can also use a rotating carrier to shoot, and you can also get a rotating effect.

This kind of lens technique is often used to express the subjective sight or dizziness of characters in rotation, or to contrast emotions and render atmosphere.

8. Shake the lens skills

This kind of lens is not widely used in actual shooting, but using this technique under appropriate circumstances can often produce strong shock and subjective emotions. The camera shake technology refers to the camera body swinging up and down, left and right, back and forth when shooting. Often used as a subjective lens, such as in the performance of drunkenness, trance, dizziness, or ship, car shaking, bumpy effect, to create a specific artistic effect. If we have carefully watched Zhang Yimou's film Speak Out, we will certainly have a deep understanding of it.

How much swing amplitude and frequency this technology needs in actual shooting depends on the specific situation. It is best to hold a camera or shoulder when shooting.

These lens technologies mentioned above are not isolated in actual shooting, but often ever-changing, and can be combined with each other to form a colorful comprehensive motion lens effect. However, when we want to use lens expression skills, we need to determine them according to actual needs. When shooting, the lens action should be even, steady and decisive. Don't abuse the lens skills aimlessly, pause or shake back and forth for no reason, which will not only affect the expression of the content, but also dazzle the audience and be at a loss. The direction and speed of lens movement should also consider the consistency of rhythm and speed of the front and rear lenses.