What is Gamma on a Monitor?
Gamma describes the relationship between the numerical value of a pixel and its actual brightness on screen. A gamma of 2.2 is the international standard for SDR content — it means mid-grey should sit at roughly 18% of peak brightness, not 50%. Without correct gamma, shadows either crush to black or lift to grey, and highlights either clip or look washed out.
Most monitors ship with gamma set to 2.2, but the actual output often drifts. Budget panels can deviate by 0.3–0.5 from the target, which is visually noticeable. Colour-critical work — photo editing, video grading, design — requires a gamma reading between 2.15 and 2.25.
How to Use the Gamma Test
Step 1 — Launch the test and go fullscreen. Press Launch Test, then F for fullscreen. Use the arrow keys to navigate to the gamma test pattern.
Step 2 — Stand back from the monitor. View the gamma ramp from 1.5–2 metres. At this distance your eye blends the fine dithered regions instead of resolving individual pixels.
Step 3 — Check the midpoint. On a correctly calibrated monitor at gamma 2.2, the central grey swatch should appear the same brightness as the surrounding fine pattern. If the solid patch looks brighter than the pattern, gamma is too low (image is too bright). If it looks darker, gamma is too high (image is too dark).
Step 4 — Check the ramp ends. The shadow end of the ramp should retain visible detail before crushing to black. The highlight end should retain separation before clipping to white.
Gamma Reading Interpretation
| Result | Meaning |
|---|---|
| Solid patch matches surrounding pattern | Gamma ≈ 2.2 — calibrated correctly |
| Solid patch brighter than pattern | Gamma below 2.2 — image too bright, shadows lifted |
| Solid patch darker than pattern | Gamma above 2.2 — image too dark, midtones crushed |
| Ramp shadow crushes early | Gamma too high in shadows — detail loss in dark scenes |
| Ramp highlight clips early | Gamma too low in highlights — detail loss in bright areas |
Adjusting Gamma
Most monitors offer a gamma preset in the OSD — typically 1.8, 2.0, 2.2, 2.4. Set it to 2.2 for SDR desktop use. Some monitors label presets as "Standard", "Movie", "Game" — the specific gamma varies by brand.
For colour-critical work, hardware calibration with an X-Rite or Datacolor colorimeter is the only reliable method. Software ICC profiles improve colour accuracy but do not correct the underlying gamma curve with the precision that hardware calibration achieves.
HDR content uses a different curve entirely — SMBTE ST 2084 (PQ) — so gamma settings only apply when viewing SDR content.
Frequently Asked Questions
What gamma should my monitor be set to? 2.2 for SDR content in a typical room-lit environment. Use 2.4 in a darker room — the higher gamma maintains contrast in dimmer ambient conditions. Avoid 1.8 (an old Mac standard) for modern content; it lifts midtones and makes images look washed out.
Why does gamma matter for gaming? In games with detailed shadow environments, low gamma makes dark areas too bright — enemies or objects that should be hidden in shadow become visible. High gamma crushes shadows so detail is lost. Correct gamma at 2.2 preserves intended game lighting.
Can I fix gamma without a calibrator? Partially. The gamma OSD preset is the first adjustment. Beyond that, monitor-specific profiles from the manufacturer sometimes improve out-of-box accuracy. For precise results, hardware calibration is required.
Does HDR change gamma? Yes. HDR uses the PQ (Perceptual Quantizer) curve, not gamma 2.2. In HDR mode, the standard gamma setting is irrelevant — the display tone-maps HDR content internally. Gamma only applies to SDR signals.