About the uniformity test
Uniformity problems hide at the extremes and show in the middle. Stepping a panel through graduated greys reveals backlight bleed at the edges, clouding in the centre, and the colour tint that makes one half of a screen look warmer than the other.
How to use it
- Turn the room lights off and go fullscreen — bleed is invisible in a lit room.
- Step through the grey levels and watch the edges and corners for lighter patches.
- Compare the left and right halves for a colour shift.
Questions
What is backlight bleed?
Light from the panel backlight escaping around the edges of the screen, visible as brighter patches in the corners on dark content. It is a normal characteristic of LCD panels, a matter of degree rather than a defect.
Why does the middle of my screen look cloudy?
That is clouding, or the dirty screen effect — uneven backlight diffusion across the panel. It is most obvious on mid greys and during slow camera pans.
Does OLED have these problems?
OLED has no backlight, so no bleed or clouding. It has its own uniformity issues instead, mostly faint vertical banding on grey.
Does this cost anything or need an account?
No. Every tool on the site is free, needs no sign-up, and works immediately in the browser with nothing to install.
Will my screen stay awake while it runs?
Turn on Keep awake and the browser holds a wake lock, which keeps the display on with no input until you leave the page.
Put this on your site
The embeddable version drops the page around it and runs the tool on its own.