How to determine the projection screen ratio and the optimal projection distance (with tools)

[Home Theater Network HDAV.com.cn] There are two factors that affect the visual effect of home theater, namely effective perspective and psychological factors, then how to determine the projection screen ratio and the optimal projection distance, the following Xiaobian share:

Effective perspective

In terms of the human visual range, within 10°, the visual acuity area, that is, the central field of view, has the strongest ability to distinguish the color and detail of the image. Information such as graphics can be correctly recognized within 20°, which is called effective field of view. 20 ° ~ 30 °, although the ability to visual acuity and color discrimination began to decrease, but sensitive to activity information, visual acuity decreased at 30 °. However, people have found that if you look at a large picture and the angle of view is large enough, the viewer will feel the same space as the picture, giving people an artistic effect of an immersive presence. Although the image content is two-dimensional, when combined, the flat image can show a three-dimensional effect. This effect makes people feel natural and moving realistic when viewing large images.

2. Psychological factors

Psychological factors also involve the impact on the quality of home theater television images. This is evidenced by a large amount of experimental data, the impact of which is comprehensive. It is related to the number of scanning lines, viewing distance, image aspect ratio, screen size, and spatial field of view. Scanning systems and screen brightness are closely related. Taking definition as an example: when a certain viewing distance, if the viewer feels that the high definition television image in the home theater is much higher than the definition of the conventional television image, then the size of the displayed image becomes smaller. Or the distance between the two images will be far away, and the difference between the two TVs will no longer be easy to detect. So high-definition TV is closely related to the big screen. If its image is displayed on a small screen, its high-definition advantage loses its meaning.

3. Determine the distance between the seat and the screen

The screen is not as large as possible. First measure the distance from the pre-installed position of the screen of the audio-visual room to the seat, and then choose the screen of moderate size, so that the space and equipment can be fully utilized and a home theater can be established. Here is a simple trial algorithm for the distance between the seat and the screen. China Home Theater Network

It is known that the distance between the viewing seat and the screen is D, the unit is cm, and S is the screen size in inches. Screen size is

S=0.164D

This calculation method is based on the viewing angle of 19°. If calculated at a viewing angle of 22°, then

S=0 .2187D

For example, the distance between the seat and the screen is 3 m, the screen size is 0.164 × 300 = 49. 2 inches, and the viewing angle is 19 °. In other words, only a 50-inch rear projection TV is needed. If you want to improve the shock and presence of the picture, the angle of view is 22° (about 4:3 height of the screen × 3 = viewing distance), the size of the screen should be 0.2187 × 300 = 65.6, the need is one Zhang is nearly 70 inches in size.

If you are using a 100-inch screen, the 19° viewing angle should be approximately 610 cm for 100/0.164 and 100/0.2187 ≈ 457 cm for 22° viewing angle. In addition, the visual sense of presence is determined by the size of the perspective, which is certainly not possible with a large screen. If you use a large 120-inch screen and the seats are placed far away from the screen, the effect is better than sitting on a 60-inch screen. Don't think that there is no room for a home theater when the room is small. In fact, using a 50-inch, 60-inch screen in a small space can get enough viewing angles, giving a fairly good visual presence, and much cheaper than using 120-inch, 150-inch projection equipment in a large space. . In addition to having a larger viewing angle and a more realistic view of the screen, if the screen is played on the same type of projection TV, the 60-inch screen is definitely brighter, the picture quality is finer, and the color is more vivid.

How to solve the visual angle problem?

For home theater, the key factor to create a sense of presence is that there is a sufficient visual angle. The factor that determines this factor is the size of the picture and the viewing distance. The visual size is determined by the “line of sight”. For example, a basketball looks very small outside 20 m, but if the basketball is 10 cm in front of your eyes, it will look very large, because the angle of view is wider. The reason. Therefore, in order to create a more shocking and more convincing visual effect, in addition to the size of the picture, the distance of viewing is also the determining factor that affects the wide or not.

A typical home theater usually uses a 4:3 TV set, and the viewing distance should be 7 times the height of the screen. For the most commonly used 29-inch TV, the actual size of the picture is only about 27 inches, and the height of the picture is about 39.6 cm. The viewing distance should be about 277 cm. If you watch TV programs in a small room, you should consider using a smaller TV. At this point, the only way to have enough perspective is to shorten the viewing distance.

However, from the perspective of home theater, the above method is difficult to meet the requirements of visual presence. The reason is very simple. Many DVDs and LD discs are currently produced in a wide screen mode. If 4:3 is used. The TV shows a 16:9 picture, minus the black border on the top and bottom of the screen. The actual display is only about 60%. Practice has shown that the horizontal viewing angle when viewing a wide screen is 25. It is the most suitable. When the horizontal angle of view is too large, just like sitting in the front of the cinema to watch a movie, open the head and neck will be sour, if the distance between you and the screen is too short, the coverage angle is too large. It will inevitably cause a "dizzy" feeling. The ideal screen size is ideally based on the width of the screen covering the line of sight of 19° to 22°. When the viewing distance is 4 times the height of the 4:3 screen, the viewing of the film is not easy to fatigue, and at the same time it can take into account the visual sense of presence. Therefore, the horizontal viewing angle should not exceed 33° at the maximum, and the minimum should not be less than 20°. The example angle of the above small room is only 11° or less, which is obviously not enough for home theater.

In fact, for home theaters with limited living space, wide-screen TVs are the most suitable. Watching TV shows or videos playing DvD discs do not have to change the viewing distance, and when wide-screen TVs play 16:9 When the video source is used, the utilization of the display portion is higher, and the vertical resolution is significantly better than the 4:3 TV. The comparison of the angles of the 4:3 and 16:9 pictures is shown in Figure 5.2. Therefore, a 4:3 TV set below 25 inches is not suitable for home theater.

1) Determine the size of the 4:3 type screen

When using a 4:3 TV in a home theater, it is recommended to use a 20° viewing angle. Unless you are using a professional TV with a good quality, it is easy to detect the device at 25° and 30°. Due to its own shortcomings, relatively speaking, because the resolution of computer monitors is high, and most of them use progressive scanning, the use of 25° and 30° viewing angles is not a problem, and eye fatigue is lower than that of ordinary TVs.

Before deciding whether to use a multiplayer screen or buy a large-sized TV set, you must pre-measure the distance between the home theater's seat and the screen. If you are using a TV or rear projection TV, you need to calculate the thickness of the TV. Go in, lest the TV set up and find that the distance is not enough. Several quick calculation formulas are provided here, and the appropriate screen size can be calculated as needed, as a reference when purchasing a 4:3 TV or a general 4:3 type projection screen.

(1) For general viewing only, not for home theater. The formula is:

Screen size = 0.086 D

The screen size is the diagonal of the actual measurement screen, in inches, and D is the predetermined distance between the seat and the TV screen, in cm. At this time, the horizontal viewing angle is 10°.

For example, if the predetermined viewing distance is 300 cm, the screen size should be 0.086×300=25.8 (inches). The domestic method for calculating the size of the direct-view TV is mostly Japanese standard, and the screen size is about 2 inches smaller than the actual size. Therefore, the actual TV set that should be purchased should be 28 inches.

(2) Double as a family opera house. To watch 4:3 audiovisual programs (such as Music Video), and occasionally look at widescreen movies, the formula is:

Screen size=0.174 D

At this time, the horizontal angle of view is 20°. This is a compromise between 4:3 picture and wide screen. The horizontal angle of view is 20°, which can meet the needs of ordinary people. The effect is very good when watching 4:3 picture, the pressure is not too big; watch 16: 9 screens, can get a relaxed and comfortable feeling, the only drawback is that the shock is slightly insufficient. If calculated by this formula, if the viewing distance is about 287 cm, it is enough to use a 50-inch screen-sized rear-projection TV. This method can save a considerable budget and the effect is good.

(3) The film on the wide screen is the main one. In order to enjoy a wide-screen movie and hope to get a stronger visual experience, the formula is:

Screen size = 0.218 D

At this time, the horizontal angle of view is 25°. Nowadays, most TV sets, rear-projection TVs and projection screens are still in the ratio of 4:3. The 16:9 projection screen is not easy to buy, and the types are small. The price of wide-screen TVs is not cheap, so in the comprehensive Under the conditions of price and effect, the only feasible alternative is to use 4:3 TV as 16:9 TV. Although it still uses 4:3 screen, the actual viewing distance is to divide the 16:9 picture height. 4 times the viewing distance, it is more suitable for watching 16:9 movies. The disadvantage of doing this is that it is more stressful when watching 4:3 programs, and it is easy to fatigue when watching for a long time, and the budget is also higher. It should also be noted that if a direct-view 4:3 TV is used, the brightness, contrast, sharpness and color of the TV should be adjusted downwards to avoid close proximity. In the case of watching TV, damage to vision.

2) Determine the size of the 16:9 TV screen

The home theater should have the best effect with a wide screen, 16:9 is the basic requirement, a wider proportion of Letter Box (mailbox)

The version, ie the 21:9 method), also has a high proportion in the video disc. The DVD also lists 16:9 as one of the three standard ratios. Based on the home theater's shock and presence, it is divided into strong, moderate and relaxed.

·Strong type

The shock and the sense of presence are strong. At this time, the formula is:

SIZE=0.268D

Where SIZE. is the size of the diagonal of the actual measurement screen, in inches, and D is the predetermined distance between the seat and the TV screen, in cm. At this time, the horizontal viewing angle is about 33. . This method is most suitable for home theaters that require shock and presence. For projection TVs, this method is extremely suitable. However, due to the close relationship between viewing distances, the pressure on the screen is large, and the vision is very easy to fatigue. After reading a film, you have to take a break. It is also important to note that this method requires very high quality and the picture must be patiently adjusted.

·Moderate

The shock and I feel moderate, and can be watched for a long time. The formula is:

SIZE=0.201D

At this time, the horizontal viewing angle is about 25. . This is the best way to get the most out of your home theater.

·Easy to appreciate the formula is

SIZE=0.161D

At this time, the horizontal viewing angle is about 20. . This method is more suitable for a family opera house based on music programs.

It is not easy to fatigue, it is a type of easy leisure, and the image quality is lower than the former two.

Projection screen ratio and optimal projection distance calculation tool download:

Projection screen ratio and optimal projection distance measurement tool

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