Monitor color test you read with your own eyes

Banding is what a smooth gradient looks like once it runs out of numbers. A channel with 8 bits has 256 values to spend between black and full, so a gradient across a 1920-pixel screen changes value roughly every 7.5 pixels; where the change from one value to the next is bigger than your eye's threshold, you stop seeing a gradient and start seeing flat strips with visible edges. Your visual system then makes it worse: at the boundary between two flat tones it exaggerates the difference, an effect called Mach banding, so the edge looks like a bright line that is not in the signal at all. This is why banding shows up worst in the places that should be smoothest — a clear sky, a studio backdrop, a dark gradient in a film.

Probably, but check three things before you conclude it. Move closer, because a 6-bit band is only about 30 pixels wide on a 1920-wide strip and a laptop at arm's length is near the limit; raise brightness, because the difference between adjacent levels shrinks as output falls; and look at the dark third rather than the middle, where the steps are perceptually largest. If the two strips still match, the panel is 6-bit — extremely common on laptops, on budget 4K sets and on fast TN gaming panels. Many of those are sold as 16.7 million colors on the strength of frame rate control, which flickers each pixel between two adjacent levels fast enough to average out the missing one; when FRC is working you will see fine shimmer rather than clean steps, and when it is not, you see 64 bands.

It depends entirely on the room and what you look at. The sRGB standard that essentially the whole web is authored for assumes a display curve of about 2.2, viewed against a 64-lux ambient with a white level near 80 candelas per square meter; a 2.4 curve in a lit room hides everything happening in the bottom fifth of the range, which is where night scenes and dark UI live. But 2.4 is also the correct answer for a television in a dark room, because BT.1886 — the reference curve for HD video production — is a 2.4 power function. So: on a desk in a normally lit room, move toward 2.2. In a blacked-out room watching films, 2.4 is right and the page is simply telling you the panel is set the way you set it.

That is the factory color temperature preset, and it is nearly always the first thing to change. Panels commonly ship on a Cool or 9300K setting because a bluer white looks brighter and cleaner in a shop, while sRGB is defined against D65, a white point near 6500 K. Confusingly, the preset that gets you there is usually the one labeled Warm — it is warm relative to 9300K, not warm in absolute terms — and monitors that label presets by number will list 6500K directly. Change that single preset and re-read the neutral steps before you touch any individual channel, because a white point shift shows up as the same tint at both ends of the scale and is not a fault worth chasing with the gain sliders.

Gain if the cast is in the bright patches, offset if it is in the dark ones, and this is the distinction most guides skip. Gain scales the top of each channel, so it moves the white point and the highlights and barely touches the shadows; offset, sometimes labeled Bias or Black Level, lifts or drops the bottom of each channel and does almost nothing at the top. A monitor menu that offers Custom Color with three R, G and B sliders is giving you gain only, which is what most consumer panels expose; offset controls tend to appear on professional monitors and on some televisions under Expert Settings. When your cast is in the shadows and there is no offset control, the fix belongs in a display profile rather than on the panel.

Neither one calibrates, in the sense the word is normally used, because neither one measures anything. Calibration means putting an instrument against the glass, reading actual output in candelas per square meter and actual chromaticity, and building a correction from the difference between what was requested and what came out. Windows' Display Color Calibration and the equivalent assistant on macOS ask you to make judgments by eye and then write a profile and a graphics card lookup table from your answers, which can absolutely improve a badly set monitor, but records your eye and your ambient light rather than the panel's behavior. This page is deliberately one step short of that: it shows you exactly specified targets and tells you which control each result belongs to, and it stops there. An entry-level colorimeter is the smallest thing that turns any of this into measurement.

No, and the distinction matters because the two are almost opposites. This page tests the display, using targets whose values are known, and treats your vision as the reliable part; a color vision test does the reverse, showing known plates to find out what your eyes do with them. Those are Ishihara plates and their relatives, they belong to an eye examination rather than to a hardware check, and there is not one anywhere on this site. If a patch here looks tinted to you and neutral to someone else standing beside you, that is worth following up with an optician rather than with the monitor's menu.