What is the difference between active and passive 3D?

Modern TVs with 3D support offer two technologies of "three-dimensional visualization" of content - active and passive. And between them there is quite a serious difference, which is manifested not only in price, but also in the quality of the display.

But in order to understand the difference between active and passive 3D, you need to know how 3D visualization works in principle.

How 3D technology works

It is possible to get a three-dimensional (3D) image from a flat screen only by transferring a separate image to the left and right eyes. Then the brain will be “deceived” and will independently complete the visual, making it three-dimensional.

However, how to submit a separate image to the left and right eyes, if the television screen is one? This is achieved through a small "duplication" of the video stream. If you look at the video with the effect of 3D "naked eye", it seems too blurry.

In fact, the video is not blurry, it just consists of two video streams - one for the left eye, the second for the right one. And special glasses allow you to separate them.

These accessories are of three types:

1. Passive anaglyph. This is one of the first 3D glasses. In them, one glass is colored blue, and the second is red. Because of this, each eye sees its own part of the image (either with blue or with a red shift);

2. Passive polarized. These glasses are used in 3D movie theaters. However, for home use, they are also suitable. Glasses or films in them have a different polarization, because of which each eye sees its half of the “picture”;

3. Active shutter. The most advanced visualization technology for 3D-enabled video. Each glass of glasses in it - a small LCD display, which either closes the eye to the video, or opens.

Each of these technologies has its own advantages and disadvantages.

How anaglyphic passive 3D works

Anaglyph technology is one of the first mechanics of 3D visualization. To watch movies with her support, you will need special blue-red glasses.

When viewing anaglyph 3D-video "naked eye" it seems that the image is twofold. Blue and red plumes appear behind each object. But it is necessary to put on this necessary accessory - and the “picture” from the screen will be converted into three-dimensional.

The fact is that the blue light filter does not let the blue cable through, and the red one - accordingly, the red one. Because of this, each eye gets "its own" picture, in which the positions of objects differ. That is why a 3D effect appears.

Anaglyphic passive 3D was most common in the 1980s. However, due to the huge number of shortcomings, it was soon forgotten. And he was replaced by the mechanics of passive 3D with polarization.

Anaglyph passive 3D does not require any special screen characteristics. So this video can be played on any TV screen. Even if your TV does not support 3D - you can still buy blue-red glasses and watch the "three-dimensional" film.

How passive 3D works with polarization

Passive 3D uses polarization technology. As a matter of fact, thin horizontal, vertical and circular strips are applied to the glasses, which do not let part of the image through. Due to this, each eye gets its own “picture”, and the brain already “completes” it to full-fledged 3D.

There are several variants of polarization for passive 3D. The simplest and cheapest is that on one glass the strips are applied horizontally, and on the second - vertically. Because of this, each eye gets its half of the picture.

The main disadvantage of this three-dimensional visualization method is the deterioration of 3D quality when the head is tilted. Watch such films or videos is only right in front of the TV and not leaning. In addition, the polarization "eats" the detail due to the deterioration of the resolution.

Suppose you are watching passive 3D on a matrix with a resolution of Full HD - 1920 × 1080 pixels. Then, after the horizontal polarization, an image of 1920 × 540 pixels is supplied; and after the vertical - 960 × 1080 pixels. Because of this, the detail is reduced.

Decreases and brightness. And this is also due to polarization.

Both of these shortcomings are devoid of glass with circular polarization. With them, you can safely tilt your head, watch movies lying in other positions. In addition, the loss in detail is slightly less, although only half of the image is still fed to each eye.

If the budget is limited, and 3D wants - it is quite possible to buy such a TV. But it is better to pay attention to models with circular rather than horizontal-vertical polarization.

How active 3D works

Active 3D - the most modern technology of three-dimensional visualization of the image. She implies that you need to watch the video with special shutter glasses. The glasses are equipped with small LCD displays that become transparent or opaque depending on the TV command.

While one glass is transparent, the second is opaque. Then change. The mode switching frequency is up to 30 Hz (once a second) depending on the specific TV model and frame rate of the film.

As a result, while watching such a movie, one eye is open, the second is closed, and this state is constantly changing. And the brain itself “completes”.

Active 3D requires both TV and glasses to support it. The latter, by the way, work on batteries and are connected to the TV via an infrared port.

Yes, definitely worth it if you want to watch 3D videos with family or friends often. But you should be prepared for the fact that for extra points for the rest of the audience will have to lay out a kilogram of money.

Which is better - active or passive 3D?

If it comes to the quality and detail of graphics, the opportunity to calmly walk around the room or lie on the couch while watching a movie - then, of course, an active 3D TV is better. But you have to pay for it. And literally - compatible with active 3D glasses are very expensive; and figuratively - the eyes are very tired, there is a headache.

If you want to save money, and you plan to watch movies every couple of weeks, at best, passive 3D will suffice. Unfortunately, this technology reduces the level of detail, but for the sake of the “wow effect” you can sacrifice the visibility of each element in the background.