UtilityGlen

Screen Test Pattern Generator

Test displays with accurate solid colors, RGB bars, gradients, alignment grids, dead-pixel checks, and screen uniformity patterns—directly in your browser.

Display Lab

Professional screen diagnostics and calibration visuals

Local rendering · No uploads

Choose test pattern

Select a test, then use fullscreen for the best inspection.

01 / 08

Solid colors

Inspect for stuck pixels, dead pixels and color contamination.

Live preview

Tip: Press F for fullscreen, ←/→ to cycle, and Esc to exit fullscreen.

Canvas resolution

—

Active test

Solid colors

Rendering

100% on-device

The ultimate visual display checklist

Your screen has a story. Every pixel tells it.

That tiny dark speck. That strange glowing corner. The gradient that looks more like a staircase than a sunset. Your display might be hiding imperfections that everyday browsing never reveals.

With the UtilityGlen Screen Test Pattern Generator, explore your display using full-screen colors, RGB test bars, smooth gradients, pixel patterns, alignment grids and uniformity tests. No specialist equipment or downloads required for basic visual inspection.

Fullscreen testing 8 test modes Local rendering
Beyond the surface

A beautiful display deserves a closer look.

A screen test is a simple way to evaluate how a monitor, laptop, television or mobile display shows different colors, brightness levels and geometric patterns.

Rather than guessing whether something looks wrong, a screen test pattern gives your eyes a consistent reference. Solid colors help reveal isolated pixel defects, gradients expose tonal transitions, and grids make alignment or scaling issues easier to notice.

Whether you're checking a newly purchased gaming monitor, examining a refurbished laptop or inspecting an OLED panel, these tests help you know what to look for.

Spot pixel defects

Inspect for dark dots, stuck subpixels and unusual colored specks.

Explore color

Compare RGB primaries and look for unexpected channel behavior.

Reveal banding

Notice abrupt shade changes where a gradient should be smooth.

Inspect uniformity

Examine uneven brightness, corner glow and tinted patches.

Eight ways to see more

Meet your display testing toolkit.

Every test has a purpose. Explore the patterns below to discover what each one can reveal about your screen.

01 / Pixels

Solid Color Test

Fill the screen with white, black, red, green, blue or a custom HEX color. One of the easiest ways to look for dead pixels and stuck pixels.

02 / RGB

RGB Color Bars

Show primary RGB bars, eight-color bars and repeating stripes to visually inspect color-channel behavior and contrast.

03 / Tonality

Gradient Test

Use black-to-white, individual RGB-channel or rainbow gradients. Look for visible bands, uneven transitions and abrupt color changes.

04 / Geometry

Alignment Grid

Display adjustable grid lines with an optional center crosshair to inspect alignment, geometry and visible scaling irregularities.

05 / Detail

Pixel Patterns

Examine alternating dots and fine horizontal or vertical lines to investigate pixel rendering, sharpness and scaling artifacts.

06 / Lighting

Uniformity Test

Examine full-screen white, gray and black levels for backlight bleed, dirty-screen effect and uneven panel brightness.

07 / Shades

Grayscale Steps

Switch between 8, 16 or 32 steps to compare shade separation, shadow detail and unwanted color tint in neutral grays.

08 / Sharpness

Checkerboard Test

Use adjustable black-and-white tiles to inspect sharp edges, screen scaling and unusual rendering artifacts.

Illustrations are examples. The actual test tool renders each selected pattern on its canvas.

Your five-minute inspection

How to test your screen like a pro.

You don't need a lab. Start with a clean display and a little curiosity.

01

Prepare your display

Clean the panel with an appropriate screen-safe cloth. Choose a comfortable brightness and, for consistent comparisons, consider disabling automatic brightness or adaptive color settings temporarily.

02

Open a solid color in fullscreen

Start with white and black, then switch through red, green and blue. Scan the entire display slowly, including the edges and corners.

03

Look for suspicious pixels

A consistently dark point may indicate a dead pixel. A bright or unexpectedly colored point may indicate a stuck pixel or subpixel defect. Check whether it remains in the same location across multiple backgrounds.

04

Inspect gradients and gray tones

Select the Gradient and Grayscale tests. Look for smooth transitions, distinguishable shade steps, unexpected color tint and pronounced banding.

05

Finish with uniformity and geometry

Use uniform gray or black backgrounds to check brightness consistency, then inspect the grid and checkerboard patterns for visual alignment and scaling artifacts.

The fullscreen advantage

Browser tabs, toolbars and desktop backgrounds can distract from tiny defects. Fullscreen mode makes the pattern easier to inspect across the available display area.

Keyboard shortcuts

F Enter fullscreen
← → Previous / next
Esc Exit fullscreen

Don't confuse dust with dead pixels.

A speck of dirt, fingerprint or screen coating mark can look like a pixel defect. Clean the surface gently and check whether the suspicious mark changes when you switch backgrounds or viewing angles.

A note about true pixel resolution

For fine pixel patterns, use 100% browser zoom and the display's native resolution when practical. Operating-system scaling, browser rendering and device pixel ratio can influence how individual pattern pixels appear.

Know what you're seeing

Screen problems, decoded.

Your display provides the clues. Here's how to interpret common visual symptoms without jumping to conclusions.

What you notice Possible explanation Helpful test pattern
Tiny dark dot Possible dead pixel or inactive subpixel; also rule out surface dust. White, red, green and blue solid screens
Bright colored dot Possible stuck subpixel or an isolated pixel defect. Black background and RGB solid colors
Bright corners or edges Potential backlight bleed, IPS glow or viewing-angle effects on applicable LCD panels. Black uniformity in a dim room
Cloudy or dirty patches Possible dirty-screen effect, uneven panel uniformity or luminance variation. Medium gray uniformity
Visible gradient steps Color banding, limited tonal precision or processing-related artifacts. Black-to-white and RGB gradients
Distorted fine patterns Possible non-native scaling, pixel mapping or rendering artifacts. Grid, pixel patterns and checkerboard
Unusual color tint Possible panel variation, color-setting differences or a color-channel issue. White, grayscale and RGB bars

These symptoms are visual indicators, not definitive diagnoses. Display type, room lighting, viewing angle, color management and connected hardware can influence what you see.

The tiny details

Dead pixel or stuck pixel?

They can look similar, but they're not always the same issue. On many LCD displays, a pixel is formed from red, green and blue subpixels. A problem affecting one subpixel can produce a noticeably different result from a completely inactive pixel.

Testing with several solid colors helps you see whether the affected point stays dark, remains illuminated or only appears abnormal against certain backgrounds.

RED GREEN BLUE WHITE BLACK

Dead pixel

Often appears as a persistently dark point because the relevant pixel elements are not producing the expected light. Exact appearance depends on panel technology.

Stuck pixel

May appear permanently bright or show an unexpected red, green or blue component. It can be easier to spot against darker or contrasting colors.

Best approach: Compare multiple solid colors, confirm the mark is not dirt, and consult the manufacturer's pixel-defect or warranty policy if you find a persistent issue.

Made for different displays

One tool. Many screens.

Different display technologies have different strengths, characteristics and things worth checking.

OLED

OLED Screen Testing

Use near-black and gray patterns to examine tinting, uneven brightness and shadow transitions. Solid colors can help reveal isolated pixel defects or persistent image marks.

Try: Uniformity + Grayscale

LCD

LCD & LED Monitor Testing

Check dark backgrounds for backlight variation and lighter screens for uneven brightness. RGB and grid tests help inspect color output and pixel mapping.

Try: Black + Grid + RGB Bars

GAMING

Gaming Monitor Testing

Inspect newly purchased high-resolution or high-refresh-rate monitors for pixel defects, banding and sharpness issues. Static patterns do not measure response time or refresh performance.

Try: Pixels + Gradients + Checkerboard

Before the return window closes

New monitor? Inspect it early.

A quick display check after unboxing can help you document noticeable issues while exchange or warranty options are still available.

This is useful for new laptops, refurbished screens, secondhand monitors and televisions as well.

Check every corner with white and black screens.
Inspect red, green and blue for pixel defects.
Look for unusual tinting across uniform gray.
Check smooth gradients for obvious banding.
Confirm the intended display resolution is selected.
Document persistent issues for the manufacturer.
Small controls. Big difference.

Built to make testing effortless.

Fullscreen inspection

Expand patterns for easier whole-screen viewing.

Custom HEX colors

Choose your own exact six-digit RGB color value.

Automatic cycling

Cycle supported color or uniformity presets at a selected interval.

Save patterns as PNG

Export the rendered canvas as an image file.

Adjustable pattern settings

Customize gradients, spacing, checker tiles and grayscale steps.

Browser-based rendering

Generate patterns locally on compatible desktop or mobile browsers.

Questions, answered

Curious about your display? We've got answers.

Learn what screen tests can tell you, what they cannot measure, and how to get more useful results from your monitor or phone.

Safe testing matters

Avoid staring at rapidly changing or uncomfortable patterns. Use moderate brightness, take breaks and stop if you experience eye strain or discomfort. People with photosensitivity should avoid rapid pattern cycling.

What is a screen test pattern generator?
A screen test pattern generator is a tool that displays controlled colors, gradients, grids and other visual patterns. These patterns help people visually inspect computer monitors, laptop displays, televisions and mobile screens for issues such as dead pixels, stuck pixels, uneven brightness, color banding and scaling artifacts.
How do I check my monitor for dead pixels?
Open the Solid Colors test, enter fullscreen, and examine the screen using white, black, red, green and blue backgrounds. Look for points that remain unusually dark or fail to show the expected color. Clean the surface first so dust and smudges are not mistaken for pixel defects.
What is the difference between a dead pixel and a stuck pixel?
A dead pixel generally refers to a pixel that is no longer operating correctly and may appear dark. A stuck pixel or subpixel can remain illuminated or show an incorrect color. Actual behavior differs across LCD, OLED and other display technologies, so the visual distinction is not always absolute.
Can a screen test fix dead or stuck pixels?
No. This tool is intended for inspection, not hardware repair. Displaying colors can help identify suspected pixel defects, but it cannot guarantee recovery of an inactive or malfunctioning pixel. Avoid applying physical pressure to the panel, which could cause additional damage.
How do I test my screen for backlight bleed?
On an LCD monitor, display a black uniformity pattern in a dimly lit room and examine the edges and corners. Look for areas that appear much brighter than the rest of the screen. Remember that viewing angle, display brightness and IPS glow can affect the appearance. OLED panels generally do not use the same conventional backlight arrangement.
What is screen uniformity, and why is it important?
Screen uniformity describes how consistently a display presents the same intended color or brightness across its surface. Uneven uniformity can appear as bright corners, cloudy areas, colored patches or a dirty-screen effect. Gray and other solid backgrounds make many of these differences easier to notice.
Why does my screen show lines or bands in a gradient?
Visible gradient banding can be influenced by limited color precision, display processing, graphics settings, browser rendering, panel characteristics or incorrect configuration. Smooth gradient tests are useful for spotting this symptom, but they cannot determine the exact hardware or software cause by themselves.
Can I test an OLED monitor or OLED phone?
Yes. OLED displays can be visually inspected with solid colors, grayscale steps and uniformity patterns. Pay attention to near-black behavior, gray tinting and isolated pixels. Avoid leaving very bright static patterns displayed for unnecessarily long periods, especially on OLED panels that are susceptible to cumulative image wear.
Does this tool work on 4K, 1440p and high-refresh-rate monitors?
The tool can display patterns on compatible monitors at different resolutions, including 1440p and 4K. Results depend on the browser, operating-system scaling and current display settings. It does not independently verify the monitor's native resolution or measure refresh rate, response time or input lag.
Can I use the screen test on a phone or tablet?
Yes, the tool is designed to work in compatible mobile browsers. Touch controls let you select patterns and change settings. Fullscreen support depends on the browser and device, so some phones may retain browser or system interface elements.
Is a browser screen test the same as professional calibration?
No. Browser-based test patterns are useful for visual inspection, but professional color calibration and objective measurements require appropriate instruments such as a colorimeter or spectrophotometer, supported software and controlled conditions. This tool does not measure color accuracy, color gamut, peak brightness or contrast ratio.
Is the UtilityGlen Screen Test Pattern Generator free?
Yes. The tool runs in your browser without a required account or specialist application installation. Patterns are generated locally using browser rendering capabilities, and you can save the current pattern as a PNG image where your browser supports the download feature.

What a visual screen test can — and cannot — tell you

This display testing tool provides visual reference patterns, not laboratory measurements. It is excellent for making visible imperfections easier to inspect, but it cannot objectively certify a display as defect-free or accurately measure Delta E, HDR performance, refresh rate, input lag, response time, color gamut, contrast ratio or peak luminance.

Results can be influenced by browser zoom, device pixel ratio, operating-system color management, display scaling, HDR settings, ambient lighting and viewing angle. If a problem is important for warranty, professional or purchasing decisions, verify it using the display manufacturer's guidance or suitable measurement equipment.

Great screens deserve a closer inspection.

From a single suspicious pixel to a perfectly smooth gradient, explore the details that make your display unique. Choose a pattern above, enter fullscreen and start investigating.

Free browser tool • No registration • Eight pattern modes
UtilityGlen

Handy web tools for daily use. Everything runs right in your browser—no sign-ups, no cloud uploads, and your data stays entirely on your device.

Tools Categories Contact Us Report a Bug Privacy Policy