Backlight Test

Detect light leaking from the edges and corners on a black background.

▶ Start test · Backlight

Look for light leaking from the edges and corners. Arrow keys toggle between black and gray. a total of 2 steps

💡 Operation tips

Click the right half of the screen to move to the next view; when the current project’s views are done it advances to the next project, and when every project is finished it exits fullscreen automatically.
Click the left half of the screen to go back to the previous view; at the very first view it stops.
After entering fullscreen, the top label and bottom buttons auto-hide after 3 seconds so you can view the screen unobstructed.
Hover in the bottom-centre of the screen for 1 second to bring the label and buttons back; move away and they hide again after 1 second.
The breathing test ends automatically after about 10 seconds.

{"mode":"backlight","basePath":"/screen","dict":{"mode":{"base":"All","purecolor":"Pixels","backlight":"Backlight","interference":"Interference","focus":"Focus","contrast":"Contrast","grayscale":"Grayscale","saturation":"Saturation","breathing":"Breathing"},"startAll":"Run the full screen check","startAllSub":"Start with the solid-color test, then work through all 8 checks in order. Click the screen or press Space to move to the next test project.","startSub":"Start test","stepLabel":"a total of {n} steps","fullscreenFail":"Could not enter fullscreen — continuing in windowed mode (patterns still display correctly).","prevView":"Previous view","nextView":"Next view","exitView":"Exit test","nextProject":"Next project","instr":{"purecolor":"Scan the screen for bright, dark or tinted (stuck) pixels. Use the arrow keys to switch colors.","backlight":"Look for light leaking from the edges and corners. Arrow keys toggle between black and gray.","interference":"Watch for moiré, streaks or related interference. Arrow keys switch patterns.","focus":"Check whether text, lines and shapes are crisp and sharp. Arrow keys switch modes.","contrast":"Assess the black-to-white gradient and tonal depth. Arrow keys flip the gradient direction.","grayscale":"Check that the gray steps are smooth with no banding. Arrow keys flip the gradient direction.","saturation":"Judge how vivid and even the saturated colors are. Arrow keys switch between colors.","breathing":"Watch the static gray screen for ~10 seconds and judge whether the brightness pulses periodically."},"colorName":{"black":"Black","white":"White","gray":"Gray","red":"Red","green":"Green","blue":"Blue","yellow":"Yellow","magenta":"Magenta","cyan":"Cyan"},"patternName":{"checkerboard":"Checkers","lines-h":"H-lines","lines-v":"V-lines","grid":"Grid"},"direction":{"left-to-right":"left to right","right-to-left":"right to left","dark-to-light":"black left · white right","light-to-dark":"white left · black right"},"focus":{"large":"Large text","small":"Small text","lines":"Thin lines","grid":"Fine grid","circles":"Circles","largeTitle":"Focus test","smallTitle":"Small-text sharpness","linesTitle":"Thin-line sharpness","gridTitle":"Fine-grid test","circlesTitle":"Circles & curves","vert":"Vertical lines","horiz":"Horizontal lines","diag":"Diagonal lines","fineGrid":"Fine grid (1px)","fineGrid2":"Ultra-fine grid (0.5px)","concentric":"Concentric circles","waves":"Wave lines","largeHint":"Check that large-letter edges are crisp, with no blur or ghosting.","smallBody1":"A paragraph for judging small-text sharpness. Look at whether the letter edges are crisp and the spacing even.","smallBody2":"The quick brown fox jumps over the lazy dog. 0123456789","smallBody3":"Smallest text — gauge readability and clarity at the minimum size."},"breathingTitle":"Breathing test","breathingEnd":"s until it ends automatically","tipsTitle":"Operation tips","tips":["Click the right half of the screen to move to the next view; when the current project’s views are done it advances to the next project, and when every project is finished it exits fullscreen automatically.","Click the left half of the screen to go back to the previous view; at the very first view it stops.","After entering fullscreen, the top label and bottom buttons auto-hide after 3 seconds so you can view the screen unobstructed.","Hover in the bottom-centre of the screen for 1 second to bring the label and buttons back; move away and they hide again after 1 second.","The breathing test ends automatically after about 10 seconds."]}}

Backlight bleeding explained

Backlight bleeding (BLB) is unwanted light leaking from the edges or corners of a panel. It is especially common on IPS displays and is also called IPS Glow.

Kinds of bleed:

Edge bleed (BLB): a white or yellow halo at the edges and corners, usually from poor sealing between panel and bezel.
IPS Glow: a silver-white halo in the corners seen from an angle — a physical trait of IPS panels that is almost impossible to avoid.
Uneven backlight: one half of the screen noticeably brighter than the other, usually from poor backlight-module alignment.

How to check correctly:

Set brightness to 30–50% (not maximum) to mimic real use.
Test in a fully dark room.
Face the screen squarely and keep a normal viewing distance (~50–70 cm).
Mild IPS Glow is normal and doesn’t affect daily use.

FAQ

What’s the difference between BLB and IPS Glow?

Edge bleed (BLB) is a white or yellow halo at the screen’s edges and corners, usually from poor sealing between panel and bezel. IPS Glow is a silver-white halo in the corners seen from an angle — a physical trait of IPS panels that shifts with your viewing angle and is almost unavoidable.

How do I check for bleed correctly?

Set brightness to 30–50% (not maximum) to mimic real use. In a fully dark room, face the screen squarely and keep a normal viewing distance (~50–70 cm). Mild IPS Glow is normal and doesn’t affect daily use.

What level of bleed justifies an exchange?

If at normal brightness and distance the bleed clearly hurts dark-scene viewing — or you see a broad yellowish halo (the “yin-yang” uneven backlight) — that is a quality-control issue and you can request a replacement.

Which panels bleed more?

IPS panels generally show more edge bleed and IPS Glow than VA because of their structure. Brands with strict factory control (Apple, Dell’s premium lines) usually have lighter bleed.