LCD Test
Seven full-screen colors that check the common faults on an LCD screen. Dark shades show backlight problems, and bright colors show dead and stuck pixels.
Seven full-screen colors. Click, tap or press an arrow key to move to the next one.
What does an LCD test check?
An LCD lights its pixels from a backlight behind them, so faults come from the light or from the pixels. Each color targets one of them.
How do I run an LCD test?
Give it two or three minutes in a dim room. These steps make faults easiest to spot.
- Let the screen run for a few minutes so it warms up.
- Dim the room, so the dark colors show what they should.
- Start the test and step through each color at your normal brightness.
- On each color, scan the screen from corner to corner.
What is a white spot on an LCD screen?
A white spot is a bright, blurry patch that shows best on white or light gray. It is not a pixel fault. It comes from the layers behind the pixels that spread the backlight evenly.
On a laptop, the usual cause is pressure: a key, a pen or a tight bag dents a layer behind the panel. On a TV or monitor, a part behind the panel can shift or come loose, which leaves a bright patch or a ring of light. A white spot does not fade with use, and fixing it means repairing or replacing the panel.
How do I test a laptop LCD outside Windows?
If you see lines, flicker or odd colors, check whether the fault is in the panel or in the graphics. Run this test in the browser first, then plug in an external monitor. A fault that shows only on the laptop screen is in the panel or its cable.
Many Dell laptops also have a built-in LCD self test. With the laptop off, hold the D key and press the power button. Colors fill the screen without Windows, so a fault that still shows is in the hardware.
Can I run an LCD test on a phone?
Yes. Open this page in the phone’s browser and tap to step through the colors. On many Samsung phones, dialing *#0*# also opens a hidden test menu with full red, green, blue and black screens.
Is my screen LCD or OLED?
Most monitors, laptops and lower-priced TVs are LCDs, and LED and QLED TVs are LCDs too. On black in a dark room, an LCD still glows faintly, while an OLED goes fully dark.
Can an LCD fault fix itself?
A stuck pixel sometimes can, and the stuck pixel test may help it along. Dead pixels, backlight bleed and clouding do not go away with use.
Do IPS, VA and TN panels show different faults?
Yes, as they are three kinds of LCD. IPS keeps colors steady at an angle but glows in the corners on black. VA shows deeper black with less glow, while TN shifts color when you look from the side.
So a silvery corner glow on an IPS monitor comes with the panel type. The same patch on a VA screen is more likely bleed.
Questions
Can I test a laptop screen this way?
Yes. Laptop screens are usually LCDs, and the test runs in any browser. Tilt the lid to where you normally have it, since the angle changes what you see.
What is the dirty screen effect?
Faint blotches or vertical bands that show on plain gray. It is easiest to notice when something pans across the screen, such as a sports broadcast.
Is some clouding normal?
A little on dark scenes is common on LCDs. Clouding that you notice in everyday use is worth raising with the seller.