Display
Your display is the window to your digital world. Verify refresh rate (60Hz/144Hz/240Hz), check for dead pixels, and test color accuracy — all in your browser.
Refresh Rate Test
refresh rate test, monitor refresh rate, Hz test
[READY]
Open Tool →Dead Pixel Test
dead pixel test, stuck pixel test, pixel checker
[READY]
Open Tool →Color Test
color test, color accuracy test, color gamut test
[READY]
Open Tool →Screen Bleeding Test
screen bleeding test, backlight bleeding test, backlight bleed test
[READY]
Open Tool →Contrast Test
contrast test, monitor contrast test, screen contrast test
[READY]
Open Tool →Color Banding Test
color banding test, gradient banding test, banding test monitor
[READY]
Open Tool →Greyscale Test
greyscale test, grayscale test, 5 gray test
[READY]
Open Tool →Frame Rate Test
frame rate test, frame rate tester, fps test
[READY]
Open Tool →Display
Your display is the window to your digital world. Verify refresh rate (60Hz/144Hz/240Hz), check for dead pixels, and test color accuracy — all in your browser.
Privacy First display Testing Tools on usbRecognized run entirely in your browser using secure Web APIs. No software download, no installation, no data upload — your privacy is 100% protected. Simply click on a tool above to start testing.
Some tools in this category are available now (marked with ✓). Others are coming soon — each coming soon page includes a detailed preview of what the tool will do and how you can test your hardware in the meantime.
Display Defects a Browser Can Detect
A full-screen colour sweep is the oldest and still the most reliable way to find pixel defects. Rendering solid red, green, blue, white and black across the whole panel makes a stuck subpixel obvious in a way that no photograph or wallpapered desktop can. A dead subpixel stays black on every fill; a stuck one holds a single colour no matter what is drawn.
Uniformity is the second family of defects a browser can show you. Backlight bleed, clouding and vignetting all appear as brightness differences across a supposedly uniform field. Because these faults are usually invisible against normal content and only appear on dark scenes, a plain grey or black full-screen fill is the correct diagnostic surface rather than a test image full of detail.
Quality control on panel uniformity is genuinely loose, so the useful question is not whether any unevenness exists but whether it is visible in normal use. A bleed patch in the corner of a laptop panel is common and often acceptable; the same patch in the middle of the screen, or one that shifts as you move your head, has a different cause and a different remedy.
Backlight Bleed, IPS Glow, and Clouding
Backlight bleed is light escaping around the edge of the panel where the bezel presses on the layers. It appears as bright wedges or streaks along the borders, it stays in the same place regardless of your viewing angle, and it is a manufacturing tolerance issue rather than a setting. It is most visible on a black background in a dark room.
IPS glow is a viewing-angle artefact, not a defect. On an IPS panel the corners appear to brighten and shift towards a purple or silver tint as you move off-axis, and the effect moves with you. If a bright corner follows your head, it is glow; if it stays fixed to the panel, it is bleed. The distinction matters because glow is not covered by any warranty.
Clouding, sometimes called the dirty screen effect, is uneven brightness across the middle of the panel rather than at the edges. It is most noticeable when a large area of similar colour moves across the screen, such as during a panning shot in a game or a slow scroll of a document. On OLED panels the equivalent symptom is usually vertical banding rather than clouding.
Colour, Contrast, and Gradient Accuracy
Colour tests confirm that each channel renders independently and that no channel is inverted or swapped. Problems here are rare on working hardware but common after a cable or adapter change, where a damaged link can drop a channel entirely or shift the colour space. A solid red fill that renders magenta points at a signal path fault rather than a panel fault.
Contrast testing is about distinguishing the darkest and lightest steps rather than measuring a ratio. A browser cannot read a panel contrast ratio, but it can show you whether the near-black steps are distinguishable from each other. If the first several dark patches all collapse into the same black, shadow detail is being crushed, which is a gamma or black-level setting far more often than a panel limitation.
Gradient banding is the most commonly misdiagnosed display fault. Visible steps in a smooth gradient usually mean the signal is being carried at reduced bit depth somewhere in the chain, not that the panel is cheap. A monitor running at 6-bit plus dithering, a cable negotiated at a lower link rate, or a colour profile applied twice can each produce banding that disappears once the specific link in the chain is corrected.
Motion: Refresh Rate, Frame Pacing, and Blur
Refresh rate and frame rate are separate measurements that are routinely conflated. The refresh rate is how often the panel redraws, which is a property of the display and its negotiated link. The frame rate is how often the content produces a new image, which depends on the application and the GPU. A monitor running at 144 Hz will happily display a 30 frames per second video and show no benefit from the extra headroom.
Frame pacing is the third quantity and the one most often responsible for perceived stutter. Average frame rate can look healthy while individual frame times vary widely, and it is the variation rather than the average that the eye reads as judder. A test that reports only an average will call a stuttering system smooth, which is why frame time consistency matters more than the headline number.
Motion blur in a browser test has to be interpreted carefully. The sample-and-hold behaviour of an LCD means a moving object is displayed for the whole refresh interval, so some blur is inherent to the technology rather than a fault. What a browser can usefully show is whether the panel is skipping refreshes, which appears as a repeating pattern in a moving test object rather than as uniform smearing.
Display FAQ
Can a browser test reliably detect dead pixels?
Yes, and it is more reliable than most people expect, because the test does not depend on the camera or on compression. Rendering a solid fill forces every subpixel to a known state. A pixel that stays dark on a white fill is dead; one that holds a colour on every fill is stuck. The only defect a browser cannot find is one hidden underneath the bezel or the taskbar area.
What is the difference between backlight bleed and IPS glow?
Backlight bleed is light escaping at the panel edges and it stays fixed in position. IPS glow is a viewing-angle effect that brightens the off-axis corners and moves as your head moves. Move side to side while watching a dark screen: a corner that follows you is glow and is normal for IPS, while a corner that stays put is bleed and may be a warranty matter.
How do I know if my monitor is running at its advertised refresh rate?
Check the rate the browser and operating system report, then compare it against the rate you selected in display settings. A monitor advertising a high rate while the operating system still drives a lower one is a configuration fault, usually caused by the cable or the port rather than the panel. The browser reports what it actually receives, not what the marketing page claims.
Why does my display show colour banding?
Banding almost always means reduced bit depth somewhere in the signal chain rather than a faulty panel. Common causes are a monitor running in a 6-bit mode with dithering, a cable or adapter that negotiated a lower link rate, or a colour profile being applied twice. Test at the native resolution and refresh rate with a single cable before concluding the panel is at fault.
What contrast ratio should I expect from my panel?
A browser cannot measure a contrast ratio, only whether you can distinguish the darkest steps from each other. What the test shows is black crush, where several near-black levels collapse into one. That is usually a gamma or black-level setting rather than a panel limit, and it is worth checking the setting before judging the hardware.
Is a greyscale test useful on an OLED screen?
It is, but it detects different faults than on an LCD. OLED panels rarely show the clouding that LCDs do, and instead tend to show vertical banding and uneven brightness in dark grey fields. Near-black uniformity is the specific weak point of OLED, so run the greyscale test with the brightness set to the level you actually use rather than at maximum.
Why does my measured frame rate differ from the refresh rate?
They measure different things. The refresh rate is how often the panel redraws, while the frame rate is how often the content supplies a new image. A browser animation is also limited by the compositor and by how much work the page is doing. A frame rate below the refresh rate tells you about the content or the machine, not about the display.
Should I test my display before or after calibration?
Test before calibrating to establish a baseline and to catch hard faults that calibration cannot fix, such as dead pixels or backlight bleed. Then test again after calibrating to confirm the gamma and black-level changes did what you intended. If you calibrate first, a crushed-black setting can mask the very gradient problems you are trying to find.