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DISPLAY DIAGNOSTICS STUDIO
Screen Tester Online Monitor & Display Free
Test your monitor, laptop, TV or mobile display for visible dead pixels, stuck pixels, screen uniformity, colour banding, sharpness and motion artifacts. Run full-screen display tests directly in your browser.
28 Test Patterns
Full-Screen Inspection
Pixel Markers
Free Browser Tool
Start Screen Testing ↗
01 / DISPLAY ENVIRONMENT
Your Screen Information
Automatically reports the display information available to your browser.
Screen dimensionsDetecting…CSS pixels
Browser viewportDetecting…CSS pixels
Device pixel ratio—Browser-reported scaling
Colour depth—Browser-reported bits
Wide colour gamutChecking…CSS media query
High dynamic rangeChecking…Browser capability signal
These are browser environment values. They do not establish your panel's native resolution, exact colour accuracy, peak brightness, refresh rate or HDR certification.
02 / SCREEN INSPECTION WORKSPACE
Professional Screen Testing Console
Choose a pattern, examine the preview and open the full-screen test for a proper visual inspection.
LIVE TEST PREVIEW
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DISPLAY PREVIEW
CURRENT TEST
PIXEL TEST
Pure Black
Look for bright pixels, unusual glowing areas and uneven dark tones.
Full-Screen Test Controls
Use the left/right arrow keys to change patterns, Space to hide or show controls, and Esc to exit. Mobile users can use the on-screen controls.
Test Configuration
Automatic cycling is intentionally slow. The tester does not use high-frequency flashing patterns.
TEST LIBRARYSelect a Display Pattern
28 MODES
Choose a pattern for the preview.28 tests available
03 / INSPECTION PROCEDURE
How to Test Your Screen Online
Use the tests in a consistent order to make visual problems easier to notice.
Scan Solid Colours
Open black, white, red, green and blue patterns. Examine the centre and corners for unusual pixels.
Inspect Gradients
Look for visible bands, abrupt tone changes or missing dark and light details.
Check Fine Detail
Use lines, grids, checkerboards and text to inspect scaling and image clarity.
Save Observations
Mark suspected locations, complete the inspection checklist and download the results.
04 / DISPLAY PIXEL GUIDE
How to Identify Dead, Stuck and Bright Pixels
A defective pixel can look different depending on its behaviour. A permanently dark point may be visible on white, while a bright or coloured point can be easier to see against black.
- Open the pure white screen and inspect every area.
- Switch to black and look for unusually bright points.
- Repeat with red, green and blue.
- Check suspected areas from a normal viewing distance and then closer.
Dust, reflections and image scaling may resemble defective pixels. A visual screen test helps locate concerns but cannot conclusively determine the cause.
IMAGE 01 / PIXEL TESTING
Dead Pixel Inspection
Add your image URL in this section
05 / SCREEN QUALITY GUIDE
How to Check Screen Uniformity and Colour Banding
Screen uniformity describes how evenly a display shows the same tone across its surface. Colour banding appears when a smooth transition looks separated into distinct steps.
- Use mid-grey and dark-grey backgrounds to inspect uneven areas.
- Try a black screen in a dim room to observe backlight glow on LCD displays.
- Use greyscale and colour gradients to check for abrupt tone transitions.
- Compare results at a normal viewing distance and with different content.
Some visible differences are affected by viewing angle, display technology, colour management and browser rendering.
IMAGE 02 / COLOUR TESTING
Colour and Uniformity
Add your image URL in this section
06 / PERSONAL SCREEN INSPECTION
Screen Test Results and Checklist
Record your observations manually. This page does not automatically identify defective display pixels.
07 / DISPLAY TEST EXPLANATIONS
What Can an Online Screen Tester Check?
Different patterns help you visually inspect different characteristics of a display.
Dead and Stuck Pixel Testing
Full-screen solid colours help you locate pixels or subpixels that appear unusually dark, bright or stuck on one colour. A browser cannot automatically inspect the physical panel for damage.
Backlight Bleed and Dark Uniformity
Dark backgrounds can reveal light leakage or bright regions on LCD displays. IPS glow may change with viewing position. OLED screens have different lighting behaviour.
Screen Colour and Grayscale
Colour bars, greyscale steps and ramps help you judge whether tonal transitions look even. They do not measure colour accuracy without a calibrated instrument.
Geometry and Sharpness
Fine grids, straight lines, circles and text patterns may reveal scaling artifacts, unusual distortion and inconsistent sharpness.
Motion and Ghosting
A moving object can help you observe trails and perceived motion clarity. Browser animation scheduling affects this visual check; it does not directly measure pixel response times.
HDR, Brightness and Refresh Rate
Normal browser APIs do not provide calibrated peak brightness, an authoritative panel refresh-rate reading or HDR certification. Browser capability signals are not measurements.
08 / DEVICE SUPPORT
Screen Testing on Desktop, Laptop and Mobile
The test interface works on modern browsers with Canvas support. It can be used on Windows computers, Macs, Android phones, tablets and supported smart-TV browsers.
Where the Fullscreen API is restricted, the tester opens a full-window inspection overlay instead. Browser bars may remain visible on some mobile devices.
09 / FREQUENTLY ASKED QUESTIONS
Screen Tester FAQs
How do I test my screen for dead pixels?
Open the full-screen tester and inspect black, white, red, green and blue backgrounds one at a time. Look closely for individual points that remain unusually dark or bright compared with the surrounding area.
Can this tool automatically find damaged pixels?
No. A webpage cannot inspect the physical display hardware or read the colour emitted by every pixel. You visually identify suspicious areas and can mark their approximate locations.
How do I test screen uniformity?
Choose the 25%, 50% and 75% grey patterns. Inspect the centre and edges for changes in brightness or tint. Try different viewing positions because panel technology and viewing angle can affect the appearance.
Can I check backlight bleed?
Yes, you can visually examine a black screen in a dim room. LCD panels can exhibit backlight bleed or glow. The appearance alone does not establish whether the display is defective or meets the manufacturer's tolerance.
Can a screen tester calibrate my display?
No. The test patterns help with visual inspection. Accurate calibration requires a measurement instrument and suitable display calibration software.
How do I identify colour banding?
Use the greyscale ramp and colour gradients. Ideally, continuous gradients should appear smooth, although graphics pipelines, browser rendering, dithering, compression and panel characteristics can affect the result.
Does this test measure my monitor's refresh rate?
No. The motion test is a visual demonstration rather than a certified refresh-rate measurement. Browser frame delivery is affected by scheduling, the operating system and display settings.
Can I test OLED and LCD displays?
Yes. Solid colours and gradients can be used on both technologies. However, backlight bleed is relevant to backlit LCDs, not self-emissive OLED pixels. Avoid leaving bright static patterns displayed longer than needed.
Does the test work on mobile phones?
Yes, the page adapts to mobile layouts. Fullscreen availability depends on the browser and operating system, and a browser may retain some interface controls.
Is my screen information uploaded?
This tester processes its patterns, inspection markers and report locally. It does not itself upload your observations, although the rest of your website may use its own hosting or analytics services.
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