Virtual Pixel in LED Screens

When choosing an LED screen, you should check the screen’s actual resolution — the physical distance in millimeters between two adjacent LED pixels — by consulting the manufacturer or supplier. Some "pseudo-producers" and unscrupulous vendors sell video screens with a lower resolution at almost the same price as screens with a normal physical resolution, and they explain the cost by stating that they are using "virtual pixel" technology.

Now consider the technology known as "virtual pixel", "dynamic pixel”, or "virtual resolution" of the video screen. Different manufacturers explain and implement this technology differently.

Generally speaking, for an LED screen with a given resolution and some specific pixel geometry, an algorithm is presented that allows, in some cases, to improve the detail of individual image fragments. The implementation of such an algorithm can be carried out in real time or previously by processing the image in some modified form.

The level of improvement of the image depends on the geometry of the pixels and the actual algorithm. This approach is perfectly valid and legitimate. However, it is necessary to weigh the pros and cons of this method.

What’s the Resultant Quality of the Picture?

Manufacturers who give examples of their implementation of the virtual pixel method illustrate their point by smoothing the edges on a black and white image of letters or numbers. If you just change the color of the displayed letters, the example crumbles.

Furthermore, even the black and white image does not take into account the color balance at the edges of the image. All LEDs are not involved in the formation of the image, only a part of the neighboring pixel is. As such, color distortions at the edges of the image are possible.

Unfortunately, we don’t have any specific and objective information about the applied image processing methods. No one has yet presented the example of two monochrome (blue, for example) parallel lines that can be visually approximated using virtual pixel technology. This would indicate a real breakthrough in image processing.

Nowhere is the question asked: Do pixel “virtualization” algorithms lead to a deterioration in picture quality? Is the proposed algorithm capable of assessing how much the quality of a given picture can improve (thereby negating the need for any modification if improvement cannot be achieved)?

The Price of "Virtualization"

Despite the fact that the pixel is virtual, its implementation requires very real (and expensive) LEDs. The aforementioned methods are based on such a redundancy of the pixel elements. Higher redundancy leads to better smoothing of the edges of the image. However, for some reason, no one ever poses a question regarding the number of LEDs on the video screen.

Consider an Example:

Let’s consider an LED screen with a pixel pitch of 20 mm and a resolution of 320 x 240 pixels. The size of this screen is 6.4 x 4.8 meters.

If the pixel consists of five LEDs, then, at a resolution of 320 x 240, the number of required LEDs will be 384,000. For a non-redundant pixel of three LEDs, 230,400 LEDs will be required. As such, the price of “virtualization” for such a video screen will be approximately 150,000 LEDs.

Now let’s reduce the pixel pitch to 16 mm. At the same aforementioned physical dimensions, we can accommodate 400 x 300 pixels. If we use three LEDs per pixel, the number of required LEDs will be 360,000. That is approximately the same as for a screen with virtualization and five LEDs per pixel.

Does this technology have “virtual pixel” advantages? Yes, it does. It allows, in some cases, to sharpen the details of the image on the video screen, while simultaneously also introducing color distortions into the image. This method is useful for images with smooth transitions but it is not suitable for images with clear borders, in which case distortions will appear on the image. Consequently, that will necessitate that you specifically prepare videos suited for such a display. Not to mention the toll it will take on live video on such a screen.

In any case, a video screen with a real resolution equal to a “virtual resolution” will always have better clarity and images. Furthermore, as a result of the “virtual pixel” technology, it is futile to even discuss doubling the screen resolution.

Basically, you should be wary of manufacturers who appear overeager to convince you of the benefits of a wonderful new technology with an “exclusive software based on a mathematical approach.”