Monitor Test — Six Patterns for Bleed, Mura and Banding
Pick a pattern and it fills the screen. Tap or click anywhere for the next pattern; use the Close button (or press Escape) to exit. A dark room makes backlight bleed much easier to spot.
A long trail behind the block means a slow-responding panel. A slight blur is normal.
About the Monitor Test
A monitor can pass a dead-pixel check and still have real problems. Light leaking from the edges of a black frame (backlight bleed), blotchy stains across a white page (mura), stripes across what should be a smooth gradient (banding), and smears trailing behind fast motion (ghosting) — none of these show up in a single-color pixel hunt. So this test works like a broadcast test transmission: six patterns, each designed to expose a different fault, shown fullscreen one after another.
Pure black reveals where the backlight escapes — best judged in a dark room. Pure white exposes stains and tint shifts, and 50% gray shows brightness differences between regions of the panel. The gradient pattern stacks a smooth ramp above a 16-step staircase so you can separate banding from normal quantization, the 2-pixel checker exposes scaling and sharpness issues, and the block sweeping side to side makes response-time ghosting visible.
The judge here is your own eye — this page measures nothing and transmits nothing. And if what you suspect is a single stuck or dead dot, that job belongs to our separate dead pixel test. This one looks at the quality of the whole canvas, not the fate of individual pixels.
How the monitor test works
- Darken the room and set the screen to your usual brightness.
- Pick a pattern to open it fullscreen; click to advance to the next one.
- On black, inspect the edges for backlight bleed.
- On white and gray, look for stains, tints and uneven brightness.
- On the top half of the gradient, look for stripes instead of a smooth ramp — the 16-step ladder along the bottom is deliberate. On the moving block, watch the trail. A long trail dragging behind it means slow pixel response; a slight blur is normal.
- Suspect an individual dot? Continue with the dead pixel test.
Frequently asked questions
I can see slight backlight bleed. Is my monitor faulty?
Faint edge bleed exists on most LCD panels — it is a property of the technology. What matters is degree: if it is clearly visible in a lit room, or bright enough to distract in dark movie scenes, it may qualify for a warranty exchange. Manufacturers differ on what they accept, so check the policy.
There are blotches on the gray screen.
Blotches on a gray field are a uniformity defect known as mura. Faint mura is common; distinct spots or bands on white and gray screens can indicate a panel defect. Pressure marks — from a finger, or packaging during shipping — are a frequent cause.
Why do I see stripes in the gradient?
Stripes in a gradient are called banding. It is common on panels driving fewer than 8 bits per channel and on compressed signals, and graphics-driver color settings can cause it too. If the smooth ramp shows stripes but the 16 steps below are cleanly separated, the signal chain is more suspect than the panel.
The moving block leaves a trail.
A trail behind a moving block is response time — how long pixels take to change color. Every LCD blurs a little, gaming panels less. Your monitor's overdrive setting can shorten the trail, though pushing it too far creates inverse ghosting (a bright corona) instead. Finding that item is the harder half, because the monitor's on-screen menu may not say overdrive at all: ASUS calls it Trace Free, BenQ calls it AMA, and LG and Samsung file it under Response Time. Names vary by model, so look for whichever item adjusts response time in your monitor's manual.
How is this different from the dead pixel test?
The dead pixel test cycles solid colors to hunt for individual dead or stuck dots. This test looks at whole-canvas quality — bleed, uniformity, tone reproduction and motion. For a new monitor, running both is the thorough option.
Is anything measured or uploaded?
No. This page only displays patterns; it measures nothing, stores nothing and sends nothing. The verdict belongs entirely to your eyes.
Is the Monitor Test free, and do I need to download a utility?
Free, with no account, no email and no download. That matters more here than on most pages: the moment you most need a monitor check is in a shop, or on a delivery you have to accept or return within a few days, and neither situation lets you install software on the machine in front of you.
Do I need a dark room or any particular setup?
For the black and gray patterns, yes — backlight bleed and blotchy shading are invisible in a bright room and obvious in a dark one. The rest is simpler: run the screen at its native resolution, use full screen so nothing else is lit, and give your eyes a few seconds to adjust before you judge anything.