Monitor Calibration Test
What to look for
A correctly set monitor shows every step as distinct. If the first two or three merge into the background, brightness or black level is set too low.
Six test patterns for checking a display by eye: black level, white level, a greyscale ramp, colour bars, gamma and uniformity. Each says what a correctly adjusted screen should show, so the patterns are diagnostic rather than decorative. This adjusts nothing. It tells you what to change in your own display settings.
How it works
- Black level shows eleven steps from RGB 0 to 20. All should be distinguishable; if the first few vanish, brightness is too low and shadow detail is being crushed.
- White level shows steps from 235 to 255. If the brightest merge, contrast is too high and highlight detail is clipped.
- The greyscale ramp should be smooth with no banding and no colour tint. Banding suggests a 6-bit panel; a tint means the white point is off.
- Colour bars should each look distinct and saturated.
- The gamma patch should match its striped surround at the labelled value when viewed from a distance. Most content assumes 2.2.
- Uniformity fields reveal backlight bleed and corner darkening, easiest to see on the black field in a dark room.
View full screen and in the lighting you normally work in. A screen adjusted in a dark room looks wrong in daylight, and the eye adapts quickly enough that a five-minute settle before judging is worth the wait.
Examples
Black level too low
Pattern
Black level
Result
The first three steps look identical to the background
Everything below RGB 6 is being rendered as pure black, so shadow detail in photographs and dark film scenes is lost entirely. Raise brightness until each step separates.
Contrast too high
Pattern
White level
Result
The top three steps all look pure white
Highlights above about 245 are clipped, so bright areas lose texture. Lower contrast until the steps separate again.
Frequently asked questions
Can this actually calibrate my monitor?
No, and no browser page can. Real calibration measures the screen with a colorimeter and writes a correction profile. These patterns let you check by eye and adjust the controls on your display, which catches gross errors but cannot produce an accurate colour profile.
Why does my screen show banding on the greyscale ramp?
Usually a 6-bit panel using dithering to simulate 8-bit colour, which is common on cheaper displays and many laptops. It can also come from an aggressive colour profile or a video driver setting. If it appears only in the browser, the profile is the more likely cause.
What gamma should I be aiming for?
2.2 for general use, which is what sRGB assumes and what nearly all web content is authored against. 2.4 is the standard for dark-room video viewing. If your screen reads noticeably below 2.2, images will look washed out compared with how they were edited.
Why does the test look different in a bright room?
Because your eye adapts to ambient light, and a screen judged in the dark will look dim and low-contrast in daylight. Test in the lighting you actually work in, and let your eyes settle for a few minutes before deciding anything.