As good as the picture is on modern high definition televisions the image on the screen is still locked in two dimensions. Many manufacturers are starting to make or at least announce televisions that will bring your viewing experience into the 3rd dimension. Some of you may remember going down to the local 7-11 to pick up those paper glasses with the red and blue cellophane lenses to watch The Creature from the Black Lagoon in 3D on your old CRT set. The idea behind those paper 3D glasses is actually much older (the first 3D film was actually made in 1922) but the basic concept continues today. 3D TV works because we have 2 eyes and space between them. Our eyes see objects at a slightly different angle and our brain uses this information to reliably calculate distance or depth, especially with objects within 20 feet. 3D media uses this natural depth perception by sending a different image to each eye, our brains do the rest.
As recently as 2007 Consumer Electronics Show show, many new DLP based 3D TVs were introduced with a new Texas Instruments chip. These DLPs use shutter glasses, a transmitter to sync the glasses to the TV and 3D source material. I viewed many of these new introductions and was very impressed by the picture performance, but the recurrent drawback to these recent 3D TVs and as well as many in the past is that over time the eyes can become strained and cause headaches. Solving this issue is one of the big challenges facing the technology. If you start to get a headache while viewing 3D media, take a break and let your eyes rest.
At first 3D TV was almost entirely found on DLP televisions but as the technology caught on and as more content becomes available plasma, LCD and LED TV manufacturers have stepped into the 3D market. At CES 2010 nearly every manufacturer had a 3D enabled TV in their line up, most of them more than 1 line of 3D TVs.
Projected 3D images work on a principle of sending a slightly different image to each of your eyes. With the old red and blue glasses the different images were projected in red and blue and the glasses filtered out one or the other to create the 3D effect. The 3D effect is fairly crude and the picture has to be monochrome since the entire effect is created by filtering colors.
Another method of producing a 3D image is using polarized lenses in the 3D glasses. Two different polarized images are shown and each lens blocks out one of the images providing a full color 3D effect that is superior to the red and blue glasses. This is the method used in IMAX and other theaters showing 3D movies. Polarization works by using filters that only let waves of light through that are not aligned with filter. Each projected image is aligned with one of the lenses and the opposite lens lets that image through. This allows 3D display of a full color picture. The polarized 3D glasses look like any average pair of sunglasses you'd find on a store rack.
A third method of creating a 3D image involves using shutter glasses. This method, often called "frame sequential display", has the user wearing powered glasses with an LCD screen that opens and closes like a camera lens. The 2 different images are shown in an alternating fashion while the glasses are synced via outboard hardware to open and close each lens separately providing one image to each eye. This effectively halves the frame rate of media being shown so a 60Hz LCD TV being used with shutter glasses will appear at 30Hz and 120Hz at 60Hz. With fast moving images this 3D technology can suffering from flickering, also the tint of the glasses effectively lowers the screen brightness by up to 50%.
Shutter glasses are also used on the 3D capable DLP TVs available currently from Mitsubishi. Samsung's final line up of DLPs that were 3D capable also used this method but Samsung has since dropped it's DLP line. The DLP version of this technology uses a grid system that displays alternating squares like a checkerboard. Think of it showing the red and black squares in an alternating fashion with each lens synced to either the red or black squares to provide the 3D effect.
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