Backlight bleeding happens with LCD monitors and televisions. Here’s how to check for blacklight bleed and solutions to fix it.
The Device Checker website offers a backlight bleed test to assess the quality of a device's display. The test involves displaying a black screen in a dark room to check for any uneven backlighting, which may cause light leakage or uneven illumination on the screen.
Liquid Crystal Displays (LCD) remains a popular choice for televisions and computer monitors.
Unfortunately, these can be affected by a defect called backlight bleeding. Occurring when light isn’t entirely blocked around a display’s bezels, the imperfection is fixable in some cases, although not always.
This irregularity most often happens when the monitor is brand new and not something that occurs after long-term use.
Although backlight bleeding can occur on any LCD type, it most affects vertical alignment (VA) displays. This LCD type offers the best contrast and image depth versus IPS (in-plane switching) and TN (twisted nematic) displays.
Without voltage, the liquid crystals found in a VA display remain perpendicular to the substrate, which creates a black display between crossed polarizers.
However, with voltage applied, the liquid crystals shift to a tilted position, allowing light to pass through to create a gray-scale display that depends on the amount of tilt generated by the electric field.
What Is Backlight Bleeding?
Backlight bleeding is a phenomenon that occurs in displays, such as LCD (liquid crystal display) or LED (light-emitting diode) displays, where light from the edges of the screen leaks through to the visible area, resulting in uneven illumination and reduced image quality.
In LCD displays, a backlight is used to illuminate the liquid crystal pixels that make up the screen. The backlight is typically placed behind the LCD panel and is designed to provide uniform illumination across the entire screen.
However, due to manufacturing variances or pressure on the edges of the display, the backlight may leak through the edges or corners of the panel, resulting in areas of brighter light along those edges or corners. This is what is referred to as backlight bleeding.
Backlight bleeding is most noticeable when the display is showing dark or black content, as the brighter patches or streaks of light along the edges or corners can contrast with the darker content, leading to a reduction in image quality.
It can manifest in different forms, such as patches, streaks, or halos of light, and the severity can vary from subtle to significant.
Backlight bleeding is generally considered a defect in display quality, as it can affect the accuracy of colors, contrast, and overall visual experience for users, especially in situations where precise image quality is important, such as in the professional photo or video editing, gaming, or watching movies.
Manufacturers may have specific guidelines or thresholds for acceptable levels of backlight bleeding in their displays, and it may be covered under warranty for repair or replacement, depending on the severity and the manufacturer's policies.
As designed an LCD display is supposed to block out excess backlight that is not needed when displaying an image or video.
When light leaks around the edges of the display, you have backlight bleeding, which affects the image and video clarity.
There are two types of backlight bleeding: flash lighting and clouding. With the former, the backlight bleeding occurs in the corners of the display.
Excessive flash lighting could cause the center of the display to look dimmer than other normal monitors. With clouding, you’ll see patches of light across the entire display when you expect a fully black screen.
Is It IPS Glow?
You might detect that your monitor is suffering from backlight bleeding. However, it might be the glow that’s associated with another type of LCD, IPS.
Short for “in-plane switching, IPS displays use liquid crystals arranged in rows between two glass surfaces to produce rich colors. With IPS glow, you’ll see a visible “glowing” around the corners of the panel when the rest of the screen is black.
Solutions to removing IPS glow include adding ambient lighting to your room and reducing the monitor’s brightness. Changing the distance and angle while you’re looking at the monitor also helps with lessening the IPS glow.
There’s a simple test you can perform to confirm your LCD has bled and not IPS glow. I suggest you perform this test immediately when you purchase a new monitor. Then, if there is a problem, you can return the monitor while its warranty is still active.
- Turn off the lights in your room. Preferably, do this at night.
- Set the monitor brightness to your desired level. Do not set it to the maximum setting.
- Open a pitch-black image or a black screen.
You can also use the website, Backlight Bleed Test by Device Checker, to test for the defect.
There are various fixes you can try to fix any minor bleeding problem. These include:
- Slightly loosen the screws at the rear of the display, which can reduce flash lighting.
- Apply black electrical tape around the edges of the display.
- Reduce the screen brightness until the backlight bleeding is no longer noticeable.
- Use local dimming when available on the monitor.
- With a microfiber cloth, softly rub the area on the display where backlight bleeding has occurred. In some instances, this can reduce backlight clouding.
When Is Backlight Bleeding Acceptable?
Some level of backlight bleeding might be unavoidable because of the technology behind LCDs. However, you’ll know soon enough when the amount of backlight bleeding on your device is not acceptable.
Hopefully, you figure this out while the monitor’s warranty is still active. Because of this, I can’t stress enough the importance of doing the backlight bleeding test when you first purchase the monitor.
If you experience backlight bleeding on your monitor, you can take various troubleshooting steps to resolve the issue. In most instances, this won’t require buying a new monitor.
The acceptability of backlight bleeding in displays is subjective and may vary depending on the user's preferences and the intended use of the display.
However, in general, backlight bleeding is typically considered acceptable when it is minimal and does not significantly impact the overall image quality or visual experience.
Manufacturers may have specific guidelines or thresholds for acceptable levels of backlight bleeding in their displays.
Typically, minor backlight bleeding that is only noticeable when displaying dark or black content and does not extend beyond the edges or corners of the display may be considered acceptable.
However, more significant backlight bleeding that is noticeable even with brighter content or extends across a larger portion of the screen may be considered unacceptable.
It's important to note that backlight bleeding is considered a defect in display quality and should ideally be minimized or eliminated in high-quality displays.
However, due to the nature of display technology and manufacturing variances, some backlight bleeding may be unavoidable in certain displays.
Que: How does LCD backlight bleeding affect image quality?
Ans: LCD backlight bleeding can result in areas of brighter light along the edges or corners of the screen, which can contrast with darker content and reduce image quality. It may appear as patches, streaks, or halos of light, and can be most noticeable when the display is showing dark or black content.
Que: Is LCD backlight bleeding normal?
Ans: LCD backlight bleeding is generally considered a defect in display quality and is not considered normal. However, due to the nature of display technology and manufacturing variances, some level of backlight bleeding may be unavoidable in certain LCD displays.
Que: Can LCD backlight bleeding be fixed?
Ans: In most cases, LCD backlight bleeding cannot be fixed by users. However, some manufacturers may provide warranty coverage for the repair or replacement of displays with significant backlight bleeding. It's recommended to contact the manufacturer or a professional technician for further assistance if backlight bleeding is affecting the intended use or visual experience of the display.
Que: How to minimize LCD backlight bleeding?
Ans: To minimize LCD backlight bleeding, users can try avoiding applying excessive pressure on the edges or corners of the display, as well as ensuring proper handling and installation of the display. Using displays from reputable manufacturers and avoiding displays with known backlight bleeding issues can also help minimize the likelihood of experiencing backlight bleeding.
Que: Is backlight bleeding covered under warranty?
Ans: Backlight bleeding may be covered under warranty by some manufacturers, depending on the severity and the manufacturer's policies. It's recommended to check the warranty terms and contact the manufacturer for further assistance if backlight bleeding is affecting the display's performance.