In lighting design, backlighting is the process of illuminating the subject from the back. In other words, the lighting instrument and the viewer face each other, with .
Table of contents
So what does this mean? Well, there's a limit to how aggressive manufactures can program the local dimming. Imagine a night landscape with a bright full moon. Ideally, the moon is bright, and the rest of the scene is dark. So in most cases, everything below the moon in our example would be brighter than the surrounding image. Here's a Photoshopped and exaggerated demonstration of what this can look like. Top and bottom As you can guess, this design has LEDs on the top and bottom edges of the screen.
The local dimming here is a little better, where the zones can be slightly smaller areas of the screen, like this:. As you can see, there's still some areas lit that shouldn't be, but it's a lot better. The idea with local dimming is you want as small and precise an area as possible ideally, per-pixel, but that's not feasible with current technology.
Remember, it's hardly ever going to look this severe, I'm merely illustrating the point so you can see it. Left and right The alternative to top and bottom.
LED LCD backlights explained
LEDs on the sides. Local dimming is similar to top and bottom. With the better TVs, there are few artifacts like these images. Instead, the processing errs on the side of safety, not allowing adjacent LEDs to get too different in brightness, so as not to have issues like you see here.
The flip side of that is less "punch" in the image, as bright objects on an otherwise dark background don't appear as bright. All sides This is a less common method now, as it requires more LEDs than any of the other edge-lighting methods. The local dimming can get a little more accurate, but is still limited to large-ish zones.
Backlight Bleed Test
If we used our moon example image, the result with an all-sides edge-lit would look just like top and bottom. But with regular video that has more light sources than just the moon , it will have a more zones to work with, sort of like this: All Sides used to be the most common edge-lighting method. But as the light guides improved, and costs had to come down to make cheaper LED LCDs , this method became fairly rare. The LEDs are arrayed on the back of the TV, facing you, but there is no processing to dim them individually.
Uniformity is generally better than edge-lit displays, but because there's no local dimming at all, the native contrast ratio is limited to the LCD panel itself which is typically much lower than the native contrast of a plasma TV. Like the "direct-lit" TVs, these have their LEDs behind the screen the image above for direct-lit works as a visual aid for this type as well.
The full local-dimming aspect means the TV is able to dim zones behind the dark areas of the screen in fairly specific areas to make the image really pop, drastically increasing the apparent contrast ratio. However, they basically don't exist. The Elite by Sharp looks amazing, but came out in and hasn't been updated with no rumors of a replacement on the horizon. The two biggest-selling TV makers in the U.
Share your voice
Vizio is claiming some of it's TVs have local dimming, but David Katzmaier recently tested one such model, the Ei-A1 , saying "Sure, black levels get darker, but the trade-off in shadow detail is one I'm not willing to make," and concluded that its "local dimming does nothing to improve picture quality. Since contrast ratio is the most important factor in picture quality , the better the local dimming, the better the apparent contrast ratio of the TV.
- Backlighting (lighting design).
- Backlight Bleed Test!
- Latest Articles.
- Silent Voice.
- .
- back·light.
Though backlit local dimming is theoretically the best, some edge-lit models like last year's HX do such a good job with their less-than-ideal LED placement that they can look fantastic. As I mentioned at the top, there's no easy way to tell, just by looking at a spec sheet, what kind of backlight a TV has.
Liquid crystal display monitors cannot produce light by themselves, and must depend on light sources to provide visible images.
- The Wren!
- .
- The Wings of Leo Spencer;
- ?
- The Web Startup Success Guide (Books for Professionals by Professionals).
- The Cutting Edge: A Suspense Novel?
- Navigation menu?
Apart from being used in computer displays, LCD televisions and smartphones, backlights are also used in small displays such as wristwatches and pocket calculators for improving the readability in low-light conditions. Unlike front lights which illuminate from the front, backlights usually produce illumination from the sides or from the back of the screen. Most liquid crystal display screens consist of several layers, with backlight being the layer farthest back. The light valves help in changing the amount of light reaching the human eyes, usually by blocking light's passage with the help of a polarizing filter.
Among these, only electroluminescent panels are capable of providing uniform light across the entire surface. For other light sources, a diffuser needs to be used for providing uniform light. White backlighting is much more predominant than colored backlighting. Backlights help in achieving thinner, lighter and more efficient displays. LCD screens making use of backlighting have a longer lifespan compared to existing monitor technologies, including OLED. However, compared to devices such as ones based on OLED technology, displays making use of backlight consume more power.
Home Dictionary Tags Hardware Electronics. Definition - What does Backlight mean?