How Passive Glasses Work?
Passive lenses rely on simple technology and are classic 3-D glasses that have anaglyph lenses. Anaglyph glasses use two different color lenses to filter the images you look at on the television screen. The two most common colors used are red and blue. If you were to look at the screen without your glasses, you would see that there are two sets of images slightly offset from one another. One will have a blue tint to it and the other will have a reddish hue. If you put on your glasses, you should see a single image that appears to have depth to it.
What's happening here? The red lens absorbs all the red light coming from your television, canceling out the red-hued images. The blue lens does the same for the blue images. The eye behind the red lens will only see the blue images while the eye behind the blue lens sees the red ones. Because each eye can only see one set of images, your brain interprets this to mean that both eyes are looking at the same object. But your eyes are converging on a point that's different from the focal point - the focus will always be your television screen. That's what creates the illusion of depth.
Today, a more popular type of passive lenses in movie theaters can be found in the polarized glasses. Again, if you look at a screen that uses this technology you'll see more than one set of images. The glasses use lenses that filter out light waves projected at certain angles. Each lens only allows light through that is polarized in a compatible way. Because of this, each eye will see only one set of images on the screen. Polarized lenses are becoming more popular than anaglyph glasses because the glasses don't distort the color of the image as much. But it's very difficult to use the polarization technique for home theater systems - most methods would require you to coat your television screen with a special polarizing film first.
How Active Glasses and 3-D-Ready Televisions Work?
In the last few years, engineers have come up with a new way to create three-dimensional images in movies and on television sets. You still wear 3-D glasses with this method, but they don't use colored lenses. The method doesn't compromise the color quality of the image as much as anaglyph glasses do. It also doesn't require you to put a polarization film on your television screen. What it does do is control when each of your eyes can view the screen.
The glasses use liquid crystal display (LCD) technology to become an active part of the viewing experience. They have infrared (IR) sensors that allow them to connect wirelessly to your television or display. As the 3-D content appears on the screen, the picture alternates between two sets of the same image. The two sets are offset from one another similar to the way they are in passive glasses systems. But the two sets aren't shown at the same time - they turn on and off at an incredible rate of speed. In fact, if you were to look at the screen without wearing the glasses, it would appear as if there were two sets of images at the same time.
The LCD lenses in the glasses alternate between being transparent and opaque as the images alternate on the screen. The left eye blacks out when the right eye's image appears on television and vice versa. This happens so fast that your mind cannot detect the flickering lenses. But because it's timed exactly with what's on the screen, each eye sees only one set of the dual images you'd see if you weren't wearing the glasses.
For several years, LCD and plasma screens weren't good candidates for this kind of technique. The refresh rates -- the speed at which a television replaces the image on the screen -- were too low for the technology to work without the viewer detecting a flicker from the glasses. But now you can find plasma and LCD displays with incredibly fast refresh rates.
Different Types of 3D Active Glasses:
There are two different types of 3-D active glasses and they aren't compatible with one another. They are the E-D and ELSA style of 3-D glasses. While emitters for both styles work with the stereoscopic sync signal standard, E-D glasses will only work with an E-D emitter. While a pair of ELSA glasses can synchronize with an E-D emitter, the glasses won't perform properly. For example, when the E-D emitter sends a signal for the left lens to be transparent, the ELSA glasses will make the left lens opaque and cause the right lens to be clear.
Even if you have a 3-D-ready television, an emitter and a pair of active glasses, not everything on your television will appear to be three dimensional. Content providers must optimize the signal for 3-D first. While it's possible to modify existing footage into 3-D content, some providers prefer to create video with 3-D in mind beforehand. Currently, the easiest way to view 3-D content is to connect a computer to your 3-D-ready television using an HDMI cable, and then stream the 3-D content from your computer to your television.
Passive lenses rely on simple technology and are classic 3-D glasses that have anaglyph lenses. Anaglyph glasses use two different color lenses to filter the images you look at on the television screen. The two most common colors used are red and blue. If you were to look at the screen without your glasses, you would see that there are two sets of images slightly offset from one another. One will have a blue tint to it and the other will have a reddish hue. If you put on your glasses, you should see a single image that appears to have depth to it.
What's happening here? The red lens absorbs all the red light coming from your television, canceling out the red-hued images. The blue lens does the same for the blue images. The eye behind the red lens will only see the blue images while the eye behind the blue lens sees the red ones. Because each eye can only see one set of images, your brain interprets this to mean that both eyes are looking at the same object. But your eyes are converging on a point that's different from the focal point - the focus will always be your television screen. That's what creates the illusion of depth.
Today, a more popular type of passive lenses in movie theaters can be found in the polarized glasses. Again, if you look at a screen that uses this technology you'll see more than one set of images. The glasses use lenses that filter out light waves projected at certain angles. Each lens only allows light through that is polarized in a compatible way. Because of this, each eye will see only one set of images on the screen. Polarized lenses are becoming more popular than anaglyph glasses because the glasses don't distort the color of the image as much. But it's very difficult to use the polarization technique for home theater systems - most methods would require you to coat your television screen with a special polarizing film first.
How Active Glasses and 3-D-Ready Televisions Work?
In the last few years, engineers have come up with a new way to create three-dimensional images in movies and on television sets. You still wear 3-D glasses with this method, but they don't use colored lenses. The method doesn't compromise the color quality of the image as much as anaglyph glasses do. It also doesn't require you to put a polarization film on your television screen. What it does do is control when each of your eyes can view the screen.
The glasses use liquid crystal display (LCD) technology to become an active part of the viewing experience. They have infrared (IR) sensors that allow them to connect wirelessly to your television or display. As the 3-D content appears on the screen, the picture alternates between two sets of the same image. The two sets are offset from one another similar to the way they are in passive glasses systems. But the two sets aren't shown at the same time - they turn on and off at an incredible rate of speed. In fact, if you were to look at the screen without wearing the glasses, it would appear as if there were two sets of images at the same time.
The LCD lenses in the glasses alternate between being transparent and opaque as the images alternate on the screen. The left eye blacks out when the right eye's image appears on television and vice versa. This happens so fast that your mind cannot detect the flickering lenses. But because it's timed exactly with what's on the screen, each eye sees only one set of the dual images you'd see if you weren't wearing the glasses.
For several years, LCD and plasma screens weren't good candidates for this kind of technique. The refresh rates -- the speed at which a television replaces the image on the screen -- were too low for the technology to work without the viewer detecting a flicker from the glasses. But now you can find plasma and LCD displays with incredibly fast refresh rates.
Different Types of 3D Active Glasses:
There are two different types of 3-D active glasses and they aren't compatible with one another. They are the E-D and ELSA style of 3-D glasses. While emitters for both styles work with the stereoscopic sync signal standard, E-D glasses will only work with an E-D emitter. While a pair of ELSA glasses can synchronize with an E-D emitter, the glasses won't perform properly. For example, when the E-D emitter sends a signal for the left lens to be transparent, the ELSA glasses will make the left lens opaque and cause the right lens to be clear.
Even if you have a 3-D-ready television, an emitter and a pair of active glasses, not everything on your television will appear to be three dimensional. Content providers must optimize the signal for 3-D first. While it's possible to modify existing footage into 3-D content, some providers prefer to create video with 3-D in mind beforehand. Currently, the easiest way to view 3-D content is to connect a computer to your 3-D-ready television using an HDMI cable, and then stream the 3-D content from your computer to your television.
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