Monitor Uniformity Test
A uniform screen shows one flat shade from corner to corner. This test fills your screen with grays from near black to white, then red, green and blue. Dim corners, tinted areas and blotches stand out on them.
Nine full-screen colors. Click, tap or press an arrow key to move to the next one.
How do I test screen uniformity?
Uniformity faults are faint, so a fair test needs a warm screen and steady settings. Work through these steps.
- Let the screen warm up for 20 minutes or so, since brightness can shift as it warms.
- Turn off dynamic contrast and any eco or ambient light mode.
- Set brightness to the level you normally use and dim the room.
- Start the test, sit square to the middle of the screen and step through each shade.
What does poor uniformity look like?
Each fault shows best at a different shade, which is why the test steps through several. Look for these.
Why does the test use so many grays?
Faults hide at some brightness levels and show at others. Clouding and dirty patches are easiest to see on dark grays, while a tint or a dim corner is clearer on mid gray and white.
The red, green and blue screens catch a different fault. If one color looks patchy while the grays look even, one set of subpixels is less even than the others.
Is it the screen or my viewing angle?
Move your head before you blame the panel. Many screens look darker or shift in color toward the edges when seen from an angle. VA and TN panels show this more than IPS.
On a large or very wide flat screen, the edges are always seen at an angle from a normal seat. A patch that stays put as you move is the panel, while one that moves with you is the viewing angle.
How do I photograph a uniformity problem?
Sellers usually ask for a photo, and phone cameras exaggerate dark patches. Stand straight in front of the middle of the screen, far enough back to fit the whole panel, and hold the phone level.
Lower the camera’s exposure until the photo looks like what you see. On an iPhone, tap the screen and drag the sun icon down. Take the photo on the gray shade where the fault shows most, and send one on white too.
Can poor uniformity be fixed?
Not fully, because it comes from how the backlight and panel were built. Some monitors offer a uniformity compensation mode that evens out brightness, at the cost of some peak brightness and contrast.
If the fault shows in normal use, report it within the return window. Take a photo with the test shade still on screen, and keep the box until the seller replies.
Do OLED screens have uniformity problems?
They avoid backlight clouding, because each pixel makes its own light. Some OLED panels still show faint vertical lines or patches on very dark grays. The 5% and 10% gray screens are the ones to watch, and the OLED screen test adds more near black shades.
Questions
Is some unevenness normal?
Yes. Almost every LCD is a little brighter in some areas than others. What matters is whether you notice it in films, games and documents at your normal settings.
Can a browser measure uniformity?
No. Reviewers measure it with a colorimeter at points across the screen. This test shows what your eyes can see, which is what decides whether a fault is worth a return.
Why do my photos of the test look worse?
Phone cameras brighten dark shades and darken the corners of every shot. Judge the screen with your eyes, and use a photo only to show a fault you can already see.