Screen uniformity test
A backlight bleed test for your screen: black, five greys and white, each over the whole screen. Look for light leaking in at the edges, cloudy patches, tinted corners or darker spots. It is free, runs in your browser and works for monitors, laptops and phones.
How to test for backlight bleed
- 1Darken the room and turn the brightness up
- 2Click "Start full screen", or pick a grey to begin with
- 3On black and the dark greys, check the edges for lighter patches
- 4On white and the light greys, look for tinted corners or dark spots
- A view of how evenly your screen lights up from edge to edge
What stays on your device
- Drawn in your browser.The greys are made by the page itself, nothing is sent anywhere
- Starts right away.Open the page and start
- You set the pace.The colour only changes when you tap or press a key, unless you turn on the timer
What you can do
- Show black, grey at 5%, 10%, 25%, 50% and 75%, and white over the whole screen
- Start with any of the seven by clicking its swatch
- Tap, click or press → for the next one. Tap or click the left quarter, or press ←, for the one before
- Let the colour change by itself every 3 seconds. This is off at first and not offered when your device asks for reduced motion
- Leave with Esc, the × in the corner or the browser's own way out of full screen
Good to know
- Bleed and clouding show best on black and the darkest greys, in a dark room
- Many LCD screens show a little light at the edges on black. The test shows it, it cannot fix it
- The × and the hint fade after 3 seconds so they don't cover the edges, and come back when you move or tap
- The screen switches between dark and bright. Stop if you feel unwell
- After 10 minutes without input, full screen closes by itself
Questions
How do I check my monitor for backlight bleed?
Darken the room, turn the brightness up and open black in full screen. Light that seeps in from the edges or corners is backlight bleed.
What is the difference between backlight bleed and clouding?
Bleed is light leaking in at the edges or corners. Clouding is patchy, uneven light in the middle of the screen. Both show best on black and the dark greys.
Why are there grey levels as well as black and white?
Dark greys show bleed and clouding that pure black can hide. Light greys show dirty spots and tinted corners.
Can the test make my screen more even?
No. It only shows the greys so you can judge the screen. It does not change anything on your device.
More tools in Numbers
That page doesn't exist. Search or drop a file below to find the tool you need.
One site for every file job. What’s yours?
Stop hopping between converter sites. Pick from 410+ tools, or a recipe that chains several.
- Files Stay On Your Device
- No watermark
- Works offline
Drop a file here
A pasted file works too.
or search for a tool
Open an app
From “ugh, this file” to done, in three steps.
- Drop it, or pick a task
No file? Search for what you need. Files are processed on your device, not uploaded for processing.
- Pick what you want
Smaller, another format, signed, merged. One click, no settings to study first.
- Make it a recipe
Need three steps in a row every week? Chain them once and run the same recipe next time.
One approved toolbox for the whole team.
In offices, on building sites and in agencies, teams handle sensitive files all day. ToolRecipe gives everyone the same tools and the same recipes, and the files are processed on each person's own computer.
- Files are processed on the employee's device
- Company recipes everyone runs the same way
- One place instead of ten converter sites