Gamma Test - Check Your Monitor Against Gamma 2.2
Use this pattern for a quick visual check around gamma 2.2. It has one reference target, not a scale that measures your display’s gamma.
What gamma actually is
Gamma is the curve mapping a pixel value to the light your panel emits. Send a monitor 128 out of 255 - halfway up the scale - and a correct display does not emit half its peak brightness. At gamma 2.2 it emits about 21.8% of peak, because relative luminance equals the relative signal raised to the power 2.2.
The curve is inherited from CRTs, whose electron guns had a native response near 2.2-2.5, and it survived because it also matches human vision.
In practice: gamma too low lifts the midtones, shadows turn grey and the image looks flat. Gamma too high sinks them and shadow detail vanishes into black. Neither is a brightness problem, and the brightness knob will not fix either.
Why 2.2 is the sRGB standard
sRGB, published by HP and Microsoft in 1996, is the colour space essentially every JPEG, PNG, web page, game UI and OS assumes unless told otherwise. Its transfer function is not a clean power curve - a short linear segment near black joined to a 2.4 exponent with an offset - but it approximates 2.2 closely enough that the two are used interchangeably.
So 2.2 is not a preference; it is the assumption the content was made under. At 1.8 or 2.6 you are not seeing what the photographer or game artist saw. Gamma is only one axis, so run a full monitor test too - a panel can track 2.2 perfectly and still have a blue-shifted white point or a dead pixel.
How to read a gamma test pattern
At 100% browser zoom, step back until the black-and-white stripes blend together. Compare them with the surrounding grey: a close match is consistent with the 2.2 target. Scaling, colour management and room lighting can change what you see. A colorimeter is needed for a measured result.
sRGB vs 2.2 vs 2.4
These three targets are close relatives, and the argument between them concerns the bottom two per cent of the signal range.
Pure gamma 2.2 is a plain power curve down to black - the safe default. The sRGB curve differs only very near black, where its linear toe lifts the deepest shadows slightly; on an LCD with an imperfect black level you will not see it, on an OLED you might. A monitor's sRGB mode is often worth using anyway, because it usually also clamps a wide-gamut panel to sRGB primaries.
Gamma 2.4, the effective target behind Rec.709 and BT.1886 video mastering, deepens shadows and adds apparent contrast. It looks excellent in a dark room on a high-contrast panel and like crushed mud in a bright office on a low-contrast IPS. For a mixed-use desktop, 2.2 wins - it is what the content assumes.
Adjusting gamma on Windows and macOS
Change gamma at the lowest level available. A monitor's own preset is applied inside the panel at higher bit depth and costs you nothing; correcting in the GPU lookup table remaps 8 bits into 8 bits, so large corrections introduce banding.
Windows
Start in the monitor's on-screen menu. Most displays expose a Gamma item with 1.8 / 2.0 / 2.2 / 2.4 presets; set 2.2 and pick the Standard or sRGB picture mode rather than a Movie or Game preset, which often layers its own curve on top.
No gamma control on the panel? Press Start, type dccw and run Display Colour Calibration; on its gamma step, move the slider until the dots in the middle patch are as close to invisible as you can get. GPU control panel sliders do the same, but are centred on 1.0 meaning "no change", not on 2.2. If gamma keeps snapping back, something is overwriting the LUT - a leftover vendor utility, a game overlay, or the calibration loading task not running.
macOS
macOS has targeted 2.2 for built-in displays since Snow Leopard replaced the old 1.8 default, so a stock Mac profile is usually close already. To change it, hold Option while clicking Calibrate in System Settings, Displays, to open Display Calibrator Assistant in Expert mode, which adds a target gamma step - though on recent macOS versions and Apple silicon Macs with built-in panels that step is often missing. On an external monitor, use the monitor's own menu: that survives an OS update, which a software LUT tweak does not.
What this gamma test cannot tell you
An uncalibrated pattern in a web browser can show whether your gamma is roughly right. It cannot measure it. There is no number here that belongs in a report, and "about 2.2" does not mean 2.20.
Several things move the answer before it reaches your eye. Ambient light shifts where you judge the merge point - the same screen reads darker beside a bright window than at night. Backlight output drifts for the first twenty to thirty minutes after power-on. The OS colour profile and the GPU lookup table sit between the pattern and the panel, so you read the whole chain, not the display. Brightness is not even across a panel either, so the centre can read differently from a corner - a screen uniformity test shows how large that spread is on your unit.
What it genuinely catches: a display well away from 2.2, a colour profile that failed to load after an update, and badly mismatched RGB channels. What it cannot give you is a measured gamma value, a per-channel curve, a white point in kelvin or a Delta E - those need a colorimeter on the glass.
Frequently asked questions
What does monitor gamma do, and is having it maxed out bad for my eyes?
Maxing gamma will not damage your eyes, but it will tire them. Gamma controls how midtones sit between black and white, so an extreme setting either crushes shadow detail into black or flattens the image into grey. Either way you are straining to resolve detail that is no longer there, and that is what causes fatigue. Set it to 2.2 and adjust brightness and contrast instead.
What's the difference between the brightness and gamma settings on screens?
Brightness moves the whole image up or down; gamma changes the shape of the curve in between. Brightness (backlight level) mostly sets how dark black is, contrast mostly sets how bright white is, and gamma redistributes everything between those two endpoints. That is why raising brightness never fixes crushed shadows - it lifts black and white together and the midtones stay compressed exactly where they were.
Should I calibrate to gamma 2.2 or to sRGB?
Pick 2.2 unless you have a reason not to. The sRGB transfer function and a 2.2 power curve differ only in the darkest couple of per cent, where sRGB's linear toe lifts deep shadows slightly. On most LCDs the imperfect black level hides that difference completely. Choose the sRGB target on an OLED or a high-contrast panel where those bottom steps are actually visible.
Gamma 2.2 or 2.4?
2.2 for a normally lit room, 2.4 only for a dark room. 2.4 is the effective target for Rec.709 video viewed in near-darkness; it deepens shadows and adds apparent punch. In a bright room, or on a panel with contrast below about 1000:1, the same setting just swallows shadow detail. 2.2 is also what web images, games and UI toolkits assume, so it is the safer default for mixed use.
I can't see details in the dark in games, but if I raise gamma my photos look washed out. What should I do?
Leave the display at 2.2 and raise gamma inside the game instead. Almost every game ships its own brightness or gamma slider precisely so you can lift shadows for that title without touching the system-wide curve. Changing gamma in the GPU control panel applies to everything, which is why your photos then look flat. Set the monitor once, correct per application after that.
Is there a way to increase gamma on a Mac display? There's no such adjustment in the colour settings.
There is no gamma slider in Displays settings - it lives in the calibration assistant. Hold Option while clicking Calibrate in System Settings, Displays, to open Display Calibrator Assistant in Expert mode, which adds a target gamma step. On recent macOS versions and Apple silicon Macs with built-in panels that step is often removed; there you are limited to switching colour profiles, using a Reference Mode, or third-party calibration software.
My gamma keeps resetting and the Windows calibration doesn't seem to stick. Why?
Something is overwriting the GPU lookup table after your profile loads. The usual causes are a leftover monitor or brightness utility running in the background, a game or overlay that resets the ramp when it exits, or the Windows calibration loading task being disabled. Check Task Scheduler for the calibration loader, uninstall old display utilities, then set gamma in the monitor's own menu instead - that setting cannot be overwritten by software.