Plasma vs LED: Picture Quality
The quality of the picture should be one your main concern when buying a television. There are many components to a good picture quality: a wide viewing angle, very dark blacks, very bright whites, accurate colors and no motion blur. Which technology (Plasma or LED) has the best picture quality? This article compares each technology in each component of a good picture quality.
|Average Viewing Angle|
A plasma screen has a better viewing angle than an LED screen. But by how much? The following picture shows you the average angle where the contrast start to be less than 50% of the maximum contrast. This is the average of viewing angles of TVs that we tested. The actual viewing angle varies per model and brand. As you can see in the video, the picture quality starts to decrease a lot earlier for an LED panel.
Do not trust the advertised viewing angle in the manufacturer specifications. Nowadays, every LED televisions will list a viewing angle of 178 degrees. While it is true that you can see the color from that angle, the picture quality will not be good, as shown in the following picture.
Do you need a good viewing angle? It depends on your room layout and your usage. You do not need a very wide viewing angle if you are watching the television alone or if your couch is directly in front of the television. However, if you have multiple sofas and a large audience, it might affect the experience of the people sitting at an angle. Also, if you hang your television very high (like above your fireplace), you will need to be far enough from the television to see the best picture.
(Smaller is better)
This is where a plasma TV really shine. When a pixel in a plasma TV is off, it emits almost no light, only 0.05 cd/m2, compared to an average of 0.15 cd/m2 for an LED. In a plasma TV, each color of a pixel is individually controlled and do not depend on the neighbours pixels. In an LCD screen, they all share the same backlight. The backlight always stays on for all the pixels (but a region can dim if the television is equipped with local dimming). The pixels are merely a filter applied on top of that light. In theory, it could still produce a real black if the pixel can block all the light, but even today's best LCD screen have a little amount of leakage. The black will appear slightly gray.
The following picture compares an LED screen to a plasma in a black scene. The LED looks more washed out because the blacks are more gray (if you do not see a difference, close the lights in your room).
If you are watching television in a somewhat lighted room, it does not matter. The LED screen will produce a black good enough you will not notice it. However, if you are in a complete dark room, you will appreciate plasma's true black.
An LED can produce an image a lot brighter than a plasma. The average maximum luminance for a plasma is 100 cd/m2 compared to 250 cd/m2 for an LCD. In an LCD screen, the source of light is separate than the color of the pixel. The source of light behind the screen, just needs to be white and has no real size constraint. This enables the uses of very bright sources of light, like CCFL or LEDs. In a plasma screen, each color of a pixel emits their own light. The gas inside a cell is excited to produce an ultraviolet light, which then excites a phosphor. This method has a lot less potential to produce a strong light.
If you have a room with a lot of windows and lights in it, or if you normally prefer to watch television with the lights on, you will appreciate the brighter image that an LCD or LED can produce.
There is no major differences between the main technologies in the accuracy of the hue of the color (the actual color, not the intensity of it). It will mostly depends on the actual model and brand of the television. Since a few years, most TVs are really good in that aspect.
Calibrated correctly, 99% of the people will not be able to say if the colors are slightly off compared to another television. The eye of humans are sensible a lot more to the intensity of the color or the clarity of the picture than the accuracy of the color.
A few televisions claims to have more colors than the others, some even add a fourth yellow pixel to the normal 3 colors (red, green and blue). The truth is, you will not see a difference. This is why the fourth yellow component always stayed as a novelty instead of becoming mainstream on all TVs; it is not worth it.
Motion blur is a problem usually found on lower end LCD televisions. It happens when an image stays on the screen longer than intended, superposing the next image. The pixels do not change fast enough to keep up with the video, making it look blurry.
A plasma TV does not have a motion blur problem because the pixels stop emitting light as soon as the electricity ceased to be applied on them. In an LCD screen, the pixels take some time to adjust its opacity based on their polarization. If the pixels do not switch fast enough, motion blur will happen.
In the last few years, LCD screens response time improved a lot, especially the higher end models and it is not a real issue anymore. Also, manufacturers introduced panels with 120Hz refresh rate (you can learn more about what is a good refresh rate here). A 120Hz refresh rate does not guarantee the absence of motion blur (nothing prevent a pixel from taking more than 1/120 second to switch) but it is a good indication that the response time of this panel is better. Also, a 120Hz televisions will create new interpolated frames between the real frames to further prevent any motion blur.
Picture Quality Conclusion
There is no doubt that Plasma wins here. Even a cheap Plasma will beat the best LED TVs in term of picture quality. Plasma televisions have a wider viewing angle, deeper blacks and no motion blur. The only point where LED beats Plasma in this category is for the brightness of the screen. An LED television can be almost three times as bright as a Plasma. This makes LED TVs more suitable for very bright rooms, like rooms with a lot of windows or open rooms.