How can you increase the image quality on your LED screen without using squared pixel technology and its related side effects? In Part 2 of this essay we will look at the other method used for increasing the image quality on LED screens known as Interpolated Technology.

Interpolated Technology is very similar to MP3 technology used in the music industry. MP3 is an audio-specific compression format based on the acoustic perception of the human ear. It provides a representation of pulse-code modulation-encoded audio in much less space than straightforward methods, by using psychoacoustic models to discard components less audible to human hearing and recording the remaining information in an efficient manner (similar principles are used by JPEG, an image compression format).

In the same way, the Interpolated Pixel is a compression based on the visual perception of the human eye: by compressing a big image to fit the small resolution available on the screen, the interpolated pixel proprietary algorithm compresses the images the way MP3 compresses sounds. This compression (together with the image persistence on the retina) allows us to control the visual perception by showing details, in our case one pixel, where there is nothing: that's why it is called “virtual.”

With this state-of-the-art technology it doesn't matter how far away the pixels are because the image quality does not rely on a geometrical distribution of the LEDs on the screen surface. It also has other key advantages. As we discussed in Part 1, "geometrical pixel" is a relatively old technology and it only works properly when LEDs are equidistant to each other. The problem is that even in this case, there can be some side effects. The main side effects are related to the minimum viewing distance, chromatic fidelity, and contrast ratio.

With minimum viewing distance if LEDs are spread all over, what actually happens is that the pixels get bigger. As the pixels get bigger, the image must be looked from a greater distance or it will appear pixelated, so the minimum viewing distance must increase. This is something to consider, especially if you are installing an LED screen indoors.

Chromatic fidelity is the distance between the LEDs and has other side effects. The closer the LEDs are to each other, the better their single colors will mix, and the sooner your eye will perceive the entire pixel color (the sum of the three basic colors: red + blue + green). On the flip side, the more distance you put between LEDs, the more distance there must be in order to perceive the right color mix. Which means that not only can images at short distances look pixelated, but they might also have a poorer chromatic fidelity (for example, the color yellow might appear as a dot half red and half green).

Last but not least, if you have LEDs spread on the LED screen, the surface might not be as black as you would like it to be to ensure the best contrast ratio. Each LED has a white (or clear) background that is much lighter than the black surface of the screen. If you spread these white LEDs on the black surface you get a grey area. Since the contrast level is a ratio between the light emitted by the LEDs and the environmental light reflected by the screen, you can very well understand that your surface should be as dark as possible.

How can Interpolated Technology avoid all these problems? Because it allows LEDs to be closer together to form a clear pixel unit. Meaning, 1. A smaller minimum viewing distance because the pixel has a smaller surface; 2. Getting a higher chromatic fidelity because LEDs are closer and therefore colors mix faster; and 3. Increasing the contrast ratio because the more space there is between LEDs the more black the surface will look.

Each manufacturer will of course highlight the strong point of its technology, but bear in mind this information and make your own conclusions. I tried to clarify a fairly complicated topic that often creates confusion. I hope I provided you with useful information that will help you to make a more conscious consideration when you have to decide which kind of LED screen better suits your needs.

Fabio Aversa is marketing manager for Euro Display LED screens, an LED screen manufacturer and supplier founded in 1978.

To read Part 1 of this article please see How The LED Virtual Pixel Really Works Part 1