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Best Gpu

Online Screen Test Tool

Professional free online screen test tool, helping you detect monitor dead pixels, light bleed, contrast, color accuracy and other key indicators, comprehensively evaluate monitor quality

Screen Color Test

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Importance of Screen Testing

Is the expensive new screen you bought absolutely reliable?

Are you sure everything is normal with your newly replaced screen?

Is the screen really problem-free after repair?

Can the old screen that hasn't been used for a long time still display normally?

How serious are the defects in the screen bought from second-hand platforms?

You should know that 20% of newly purchased screens actually have defects that go unnoticed, and 80% of screens are prone to minor defects within half a year, but many people don't notice.

Usage Instructions

  • •Click any test mode to enter fullscreen test interface
  • •Carefully observe the screen during testing, look for abnormal pixels
  • •Press ESC key or click screen to exit test
  • •Press I key to hide/show test instruction text
  • •Recommended to test under normal indoor lighting, avoid strong light interference

Test Result Recording

Screen Test Algorithm Principles

Dead Pixel Detection Algorithm

Dead pixel detection is based on RGB color model, identifying abnormal pixels by displaying solid color backgrounds. Algorithm principles are as follows:

Dead pixel detection formula:
RGB(255,255,255) → White background detects dark spots
RGB(0,0,0) → Black background detects bright spots
RGB(255,0,0) → Red background detects green/blue channel dead pixels

Contrast Calculation Formula

Contrast test uses Weber contrast formula and Michelson contrast formula:

Weber contrast = (L_target - L_background) / L_background
Michelson contrast = (L_max - L_min) / (L_max + L_min)
Where L represents luminance values

Grayscale Test Calculation

Grayscale test uses Gamma correction formula to evaluate monitor brightness linearity:

Output brightness = (input value / 255)^γ × maximum brightness
Standard γ value = 2.2
Grayscale levels = 0, 17, 34, 51, 68, 85, ..., 255

Screen Test Types Detailed Explanation

Dead Pixel Detection

Detect dead pixels, bright spots and dark spots on screen by displaying solid color backgrounds. Dead pixels are common defects in monitor manufacturing process, affecting display quality.

Light Bleed Test

Detect LCD monitor backlight bleeding issues. Observe screen edges and corners for abnormal light emission under black background.

Contrast Test

Evaluate monitor contrast performance, test brightness difference between black and white. High contrast provides better image quality and depth.

Color Test

Detect monitor color accuracy and saturation. Test monitor color performance through RGB primary colors and mixed colors.

Grayscale Test

Test monitor grayscale level display capability. Examine monitor brightness linearity and level performance through different grayscale values.

Breathing Effect Test

Detect monitor brightness flickering issues. Some monitors exhibit periodic brightness changes when displaying static images.

Screen Test Example Demonstrations

Example 1: Office Monitor Test

Device: 24-inch 1920×1080 IPS Monitor

Test Steps:

  1. Pure white background test - Found 1 dark spot in upper left corner
  2. Pure black background test - Slight light bleed at bottom edge
  3. Grayscale test - Can clearly distinguish 16 grayscale levels
  4. Color test - RGB three colors display normally

Conclusion: Monitor overall quality is good, minor defects exist but don't affect daily use.

Example 2: Gaming Monitor Test

Device: 27-inch 2560×1440 144Hz Monitor

Test Focus: Response speed, contrast, color accuracy

Test Results:

  • Excellent contrast test - Deep blacks, bright whites
  • No obvious dead pixels or light bleed
  • High color saturation, suitable for gaming and multimedia
  • Natural grayscale transitions, rich levels

Related Screen Test Tools

Monitor Detection Tools

  • • LCD monitor test software
  • • OLED screen detection tools
  • • 4K monitor test programs
  • • Curved screen test tools
  • • High refresh rate screen tests

Professional Detection Items

  • • Color gamut coverage test
  • • Delta E color accuracy
  • • Brightness uniformity detection
  • • Response time test
  • • Input lag measurement

Mobile Device Tests

  • • Phone screen test tools
  • • Tablet display tests
  • • Laptop screen detection
  • • Touchscreen calibration tools
  • • Multi-touch tests

Screen Test FAQ

Q: How long does screen testing take?

A: Complete screen testing usually takes 5-10 minutes. Basic dead pixel detection takes 2-3 minutes, comprehensive testing including contrast, color, grayscale and other items requires more time. It's recommended to observe each test item for more than 30 seconds.

Q: What to do if dead pixels are found?

A: A few dead pixels are normal. If the number of dead pixels exceeds 3 or they are located in prominent central positions, and within warranty period, you can contact the manufacturer for repair or replacement. Some manufacturers have clear warranty policies for dead pixels.

Q: How serious is light bleed?

A: Slight edge light bleed is common in LCD monitors and doesn't affect normal use. If light bleed seriously affects viewing experience, especially when watching dark content in low-light environments, consider replacing the monitor.

Q: How to judge screen test results?

A: High-quality monitor standards: fewer than 3 dead pixels, no obvious light bleed, can clearly display 256 grayscale levels, vibrant colors, high contrast. Professional use recommends using colorimeters for precise measurement.

Q: What are the testing focuses for different monitor types?

A: IPS panels focus on color accuracy and viewing angles; VA panels emphasize contrast and black performance; TN panels focus on response speed; OLED panels check burn-in risk and brightness uniformity.

Q: Screen test environment requirements?

A: Best test environment: soft and even indoor lighting, avoid strong light directly on screen, appropriate viewing distance (about 50-70cm), monitor warm-up for more than 15 minutes. Turn off auto brightness adjustment before testing.

Screen Maintenance and Care Suggestions

Daily Maintenance

  • ✓Regularly clean screen with dedicated cleaner and microfiber cloth
  • ✓Avoid touching screen surface directly with fingers
  • ✓Control indoor humidity, avoid overly humid environments
  • ✓Adjust brightness appropriately, avoid long-term maximum brightness use

Preventive Measures

  • ✗Avoid displaying static images for long periods to prevent burn-in
  • ✗Don't scratch or hit screen with hard objects
  • ✗Avoid strong magnetic field effects on display
  • ✗Don't place heat sources near monitor

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Professional free online screen test tool, comprehensively detect your monitor quality

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