3D - What You Should Know about 3D in This Quick Guide

3D (three-dimensional) means something that has width, height and depth (length). It is a concept relative to 2D (something only has width and height).

3D movies refer to the motion pictures adding stereoscopic vision. 3D Blu-ray Movie is encoded at 1080p/24 and delivers full HD 1080p resolution to each eye.

Stereoscopic principal - Polarizing Theory

3D movies are made use of human eyes' visual angle difference and convergence to produce stereoscopic effect.

Human visual can tell far or near distance because of the distance between two eyes. There are about five centimeters between left eye and right eye and two eyes' visual angle are different when seeing something except when starring at the front. Although the difference is small, after being transferred to brain via retina, our brain can use this small difference to produce far or near depth thus to produce stereoscopic effect. We call this principal "Polarizing Theory".

According to this principal, if we make two separate images of a same picture from two eyes' visual angle difference, and show these two separate images simultaneously - one to each eye, we can feel the stereoscopic effect of the image with the help of special projection hardware and/or eyewear like 3D glasses.

Common 3D Movies Formats

Common 3D film formats include Anaglyph and Split Screen.

1. Anaglyph

Anaglyph 3D were the earliest method of presenting theatrical 3D and it requires less specialized hardware.

Anaglyph refers to color filtered 3D pictures including amber/blue, red/green, red/blue and red/cyan. Among these 3D image flavors, red/cyan is the most popular one.

According to Wikipedia, "In an anaglyph, the two images are superimposed in an additive light setting through two filters, one red and one cyan. In a subtractive light setting, the two images are printed in the same complementary colors on white paper. Glasses with colored filters in each eye separate the appropriate images by canceling the filter color out and rendering the complementary color black."

To watch the Anaglyph 3D video, what you need is just a pair of archetypical 3D glasses. And you can play the 3D video on common TV, computer monitors, and even the common portable devices.

2. Split Screen 3D

Split screen 3D can be divided into Side by Side 3D and Top and Bottom 3D.

Side by Side 3D - In 3D Side by Side, one frame consists of two halves on the left and right, with the entire frame for the left eye scaled down horizontally to fit the left-half of the frame, and the entire frame for the right eye scaled down horizontally to fit the right side of the frame.

When the 3D ready TV receives this 3D Side by Side signal, it splits each frame to extract the frame for each eye, and then rescales these individual frames to a full HD resolution using upscaling algorithms. It then displays these upscaled individual frames alternately in a frame-sequential manner.

The difference between Side by Side (Half-width) and Side by Side (Full)

Side by Side (Half-width)

Side by Side (Full)

Let's take a 720p (resolution of 1280×720) source video as an example.

If you choose the Side by Side (Half-width), the output video frame for the left/right eye will be at a 640×720 resolution, and the resolution of the output video will be 1280×720.

If you choose the Side by Side (Full), the output video frame for the left/right eye will be at a 1280×720 resolution, which means the resolution of the output video will be 2560×720. So before you choose the Side by Side (Full) as the output 3D mode, you should check whether the device supports the output video resolution first.

	Side by Side (Half-width)	Side by Side (Full)
Resolution of the left eye frame	640×720	1280×720
Resolution of the right eye frame	640×720	1280×720
Resolution of the entire frame	1280×720	2560×720

Top and Bottom 3D - In the Top and Bottom 3D format, one video frame is divided into two sub-frames, the upper one consisting of the sub-frame meant for the left eye and the lower sub-frame meant for the right eye.

Top and Bottom (Half-height)

Top and Bottom (Full)

And the difference between Top and Bottom (Half-height) and Top and Bottom (Full) can be largely understood the same as the difference between the two Side by Side modes. The output Top and Bottom (Half-height) 3D video will keep the resolution of the source video, and the output Top and Bottom (Full) will double the vertical resolution of the original video.

When playing a Side by Side 3D or Top and Bottom video, a 3D PC or 3D TV and the assorted 3D glasses are necessary. But the visual effect of Side by Side 3D and Top and Bottom 3D video is much better compared to that of Anaglyph 3D video.

3D TV and 3D Glasses

3D TV is television that conveys depth perception to the viewer. 3D glasses refer to any form of stereoscopic viewers.

3D display technologies include two types: With lenses (anaglyphic 3D system, active shutter 3D system and polarization 3D system) and without lenses (glasses-free 3D system).

1. With lenses

Anaglyphic 3D

Anaglyphic 3D uses passive color filtered 3D glasses. This technique has the longest history and the 3D imaging principle is simple. The cost is quite low - 3D glasses cost is only a few dollars. However, the 3D effect is the worst and this technology is not widely used.

Active Shutter 3D

Active Shutter 3D uses rechargeable 3D glasses. The lenses are actually two LCD screens. The current controls two lenses transmitting light alternatively and in the meantime, the 3D TV display twinkles alternatively in keeping with lenses. In this way, our eyes can see two separate images and 3D images are produced in our brain.

Advantage:

Stereoscopic effect is strong.

Weakness:

The alternatively twinkling image may make us dizzy and we cannot feel 3D effect when lying down. The 3D glasses are heavy and need recharge frequently thus have a bad influence to vision.

Active shutter 3D TVs include:

Samsung H6400, Samsung H7150, Samsung H8000, Samsung HU8550, Samsung HU9000, Sony W800B, Sony W850B, Sony X900B, Sony X950B, etc.

Polarization 3D

Polarization 3D uses 3D glasses with liquid crystal membrane like sunglasses. The TV screen has an outer membrane matched with the 3D glasses and when watching 3D videos on TV, the outer membrane makes separate images filtered through left and right lens and then 3D effect is produced in our brain.

Advantage:

The picture is stable and comfortable for longtime watching and there is no sitting position limitation. The 3D glasses are light and need not charge thus have little bad influence to vision.

Weakness:

The stereo sense is relatively weaker, but it's hard to tell without professional knowledge.

Polarization 3D TVs include:

LG LB7100, LG LB7200, Sony W950B, Sony X850B, etc.

2. Without lenses

Glasses-free 3D

When watching glasses-free 3D, we need to keep certain distance with the display device (3D effect has big relationship with viewing angles). The 3D effect is worse compared with active shutter 3D and polarization 3D.

Advantage:

The biggest advantage is to get rid of the shackles of glasses.

Weakness:

There are still many problems for resolution, visual angle and visual distance, etc.

Glasses-free 3D TVs include:

Samsung 55-inch Glasses-Free 3D UHD TV, Sharp 85-inch 8K Glasses-Free 3D TV, Toshiba 56-inch Glasses-Free 3D TV, Haier Glasses-Free 3D TV, Leyard 110-inch Glasses-Free 3D TV, etc.

2D to 3D Conversion

Sometimes you only have 2D videos but are eager to experience 3D effect. You may ask is there a way to achieve so except buying another 3D video? The answer is yes. You can convert 2D to 3D video with 2D to 3D software. Then you are able to enjoy your converted 3D videos on your 3D TV, 3D video player or other 3D devices.