What is a dead pixel?
When you check for your smartphone, laptop, or computer screen or monitor specifications on the internet, some of the features you will see are the resolution of the screen and the pixels it has per inch. Pixels are dots on your screen that turn on or off to display everything on your device’s screen: information, video, images… Sometimes, a pixel can die, causing odd dots on your screen. But what is a dead pixel? And do you really understand what the term pixel means and what it means to have dead pixels on your device? If you don't, don’t worry because that is what this article is all about. We’re going to let you know what a dead pixel is and everything else you need to know about pixels: how pixels work, what it means for a pixel to be dead, what causes dead pixels, and how to detect the dead pixels. Just make sure you read this article untill the end.
What is a pixel?
In digital imaging, a pixel is the smallest addressable element of an image. If you tried to zoom any of your photos on your phone or PC, you will likely start seeing small squares, which may vary in number based on the quality of the device that was used to take the image. When it comes to displays, a pixel is also the smallest element of a display that is normally in the form of squares. Pixels are arranged in a grid to form a display, and the number of pixels in the grid determines the resolution of the display. The more pixels there are, the higher the resolution, and the sharper and more detailed the image will be. In a digital image, each pixel represents a single point in the image, and the combination of these pixels creates the overall picture. You may find below an example of a high-resolution image and a second low-resolution one. The first is a landscape scene of palm trees in the desert. We have drawn a square on the palm tree leaves, and have maximized it to make the second image. As you can see, zooming in reveals the small dots that constitute your image.
Regular image
Zoomed-in image
Distinguishing rendered pixels from physical pixels
The pixels in the two images above are not physical pixels. They are rendered by your computer. Rendered pixels are the number of pixels that an image is actually composed of when it is displayed on a screen. This number may be different from the number of physical pixels on the display, as the image may be scaled to fit the screen. Physical pixels, on the other hand, refer to the actual number of dots on a display that make up an image. The more physical pixels there are, the higher the resolution and the sharper the image appears. For example, a display with a resolution of 1920x1080 pixels has a total of 2,073,600 physical pixels.
If you closely look at your TV at home while it is turned on, you will see very small squares or dots on the screen. The combination of these small squares is what gives your TV the ability to display images and videos. In situations where the display has too many pixels per inch, you will likely not be able to see the individual Pixels – Apple calls this retina display.
This is most likely the case with most of the newer smartphones that have come through in recent years. Most of them have over 300 pixels per inch, which makes it almost impossible to see the individual Pixels with your naked eyes.
How do pixels work?
Pixels are the individual elements of a digital image or display. They are the smallest units of an image that can be manipulated to create a complete picture. In a display, each pixel is made up of three dots called sub-pixels, each of which is responsible for displaying one of the three primary colors: blue, green, and red. The intensity of each of these colors can be adjusted to create the desired color for each pixel. By combining the colors of multiple pixels, a full image is created. So, if you want to display an entirely red image, only the red sub-pixels shall emit light, which will then make the entire display to be red.
In another scenario, turning on the red and green subpixels will produce yellow, turning on all the three subpixels produces white, and turning on-off all of them shows black. That's how each pixel produces the desired color that when combined create the images that we see on the screen.
Change the intensity of each primary color to change the color of the pixel
In the case of videos, the change of colors for each pixel change in rapid succession at a speed that depends on the frames per second for the video being played on the display. The fact that the changes happen so fast is the reason it is hard to see with our naked eyes how each pixel changes color.
The number of pixels per inch that a display has will largely determine the quality of images and videos it will show. The smaller they are, the sharper the image will look! That is why the same video will appear different on an HD (1280 x 720 pixels) display and a Full HD (1920 x 1080 pixels) display.
What is a dead pixel?
A dead pixel is a single point on a display screen that is not functioning properly and shows a solid color, usually black or white - generally sign of a dead pixel - or a single color - generally sign of a stuck pixel -, instead of displaying the expected dot constituting the image being displayed. This occurs when the transistor that powers the pixel fails, and as a result, the pixel no longer receives the necessary electrical power or signals to display the intended colors. Dead pixels are caused by a number of factors, including manufacturing defects, physical damage, water damage, or age.
The number of dead pixels or stuck pixels on a screen can range from just one to many, and the size of the affected area will depend on the number of pixels that are dead at a given point. If you suspect that your display has dead pixels, you can test for them by displaying a solid color on the entire screen and looking for any odd-looking dots that may appear. If you find a dead pixel, it is important to check if it is covered by your device's warranty, as some warranties may cover dead pixels, while others may not.
Distinguishing dead pixels from stuck pixels
A dead pixel is a pixel that is not functioning correctly, and as a result, it displays a black or white color. On the other hand, a stuck pixel is a pixel that is stuck displaying a single color and cannot change to other colors.
You can distinguish between a dead pixel and a stuck pixel by performing a dead pixel test. In a dead pixel test, you display a series of solid-color screens such as red, green, blue, and white, and observe if there are any pixels that are not functioning correctly. If a pixel appears black or white in all color screens, it is a dead pixel. If it displays a single color that does not change, it is a stuck pixel.
When and why can a pixel die?
There are several causes of dead pixels, and some of these include the following:
Manufacturing defect
While manufacturing a display, errors can occur that could result in having one or more transistors of your display not working. Most of the companies that make displays always test each screen after manufacturing to make sure all its pixels work well. However, some of the tests are not effective enough to identify the dead pixels, especially if the display has too many pixels.
Physical damage
When you drop your phone or laptop on the ground, the force as a result of this drop could cause some of the pixels to get damaged. The display itself may continue working properly, but with some sections of the screen not displaying any content. If the dead pixels are very few, you may not even realize it, more so on smartphones that have over 300 pixels per inch. In some cases, the damages can gradually worsen, whereby the pixels fail one at a time until the point when the dark spot on your screen becomes visible.
Water damage
If your device gets splashes of water or when it gets immerged in water, one of the most vulnerable parts that could easily get messed up is its display more so if it is not water resistant. This is because when the transistors that power up you display pixels get in contact with water, they fail immediately. If your work or home environment involves getting in contact with water more often, just get yourself a water-resistant device.
Aging
Just like any other electronic device, displays age with time, which leads to the gradual failure of some pixels. For quality displays, this takes a lot of time to happen unless you handle your device carelessly during use. Most of the modern devices can be used for more than ten years without experiencing any issues with the display pixels. So, it will be a case of bad luck to find dead pixels due to age, but it does happen.
How can I know if one my pixels is dead?
Are you spotting odd dots on your screen? You probably have a dead or malfunctionning pixel. The most common method to spot them is to display one color at a time on your whole screen.
Display one color at a time on your display
What you should do is test displaying several colors on the entirety of your screen to see if you notice any odd-looking dots. Remember they can be dark, white, or any color that is a combination of the 3 primary colors (at their full intensity). Hence the pixel can be either "dead", or "stuck". We would recommend testing all the primary colors and all their combinations before you conclude that you don’t have any dead pixels.
You can perform a dead pixel test on your screen on DeadPixelTest.org. We provide a simple and effective way to test for dead pixels on your screen. When you visit the website, you will be presented with a series of solid-color screens, each of which is designed to highlight any dead pixels on your screen. To perform the test, simply follow the instructions which will guide you through the process of testing your screen for dead pixels. If you have any dead pixels, they will be easily noticeable as small, discolored dots on the solid-color screens.
Conclusion on dead pixels
Getting dead pixels is quite a common problem that is caused by a couple of reasons that lead to the failure of transistors that power up these pixels. Like we have seen above, the commonest causes of dead pixels are; manufacturing defects and physical damages.
If you suspect any form of dead pixels on your device’s display, you can use our dead pixel testing tool. Afterwards, check if your device's warranty takes dead pixels into account. Normally it takes a minimal number of dead pixel for the warranty to come into play... Good luck with your screens!