Gamma Test

Introduction

The DeviceHub Gamma Test is a free online set of gray ramps and gamma-oriented reference patterns that help you visually judge whether midtones and shadow transitions look plausible on your monitor, without pretending to be a hardware calibrator. Photo editors noticing milky or crushed midtones, video editors checking lounge monitors, console players tuning TV gamma presets, and IT admins fixing a washed-out conference display use browser charts as a quick orientation. Open the page fullscreen, study labeled ramps, and adjust display brightness or gamma presets thoughtfully. DeviceHub emphasizes visual judgment: these patterns are not a substitute for a colorimeter measuring a 2.2 gamma target across a grid. Browser compositing, OS color management, and HDR tone mapping all intervene. Pair with Black Level and White Level Tests for clipping, Contrast Test for punch, Gradient Test for banding, and HDR Test for capability signals only, not calibrated HDR laboratory metering. Midtone weight makes or breaks photo edits and streaming grades long before anyone measures a 2.2 target with a colorimeter, yet washed or heavy mid grays are easy to mis-blame on “bad contrast” alone. DeviceHub’s Gamma Test offers gray ramps and gamma-oriented reference patterns so you can visually judge whether transitions look plausible on this monitor through the browser, without pretending the page is a hardware calibrator writing LUTs. Photo editors noticing milky midtones, video editors checking lounge screens, console players tuning TV gamma presets, and IT admins fixing a washed conference display use these charts as orientation before deeper Black Level and White Level checks. Visual judgment is the method: browser compositing, OS color management, and HDR tone mapping all intervene, so DeviceHub will not certify DICOM or broadcast gamma from a tab. Pair with Contrast Test for punch, Gradient Test for banding that masquerades as gamma failure, Color Test for hue casts, and HDR Test strictly for browser/CSS/media capability signals, not calibrated HDR laboratory metering. Permissions remain none, so locked machines can still run a five-minute tone sanity pass after someone “optimized” a TV picture mode overnight. Streaming creators who grade on a bright desk often raise brightness until midtones look fine in the room yet crush on a properly dim reference, DeviceHub’s charts will not replace a meter, but they will show when a lounge TV’s “cinema” preset still sits far too bright relative to labeled gray steps. Document ambient conditions beside any before/after notes so a second look tomorrow is comparable. If banding appears while you hunt midtones, pivot to Gradient Test rather than endlessly twisting gamma. Permissions remain none throughout, matching the rest of the display suite.

What this tool does

Charts show stepped or continuous grays and gamma reference imagery with guidance on what “too dark” or “too bright” midtones often look like. The tool does not write GPU LUT calibration. It does not upload your adjustments. Dynamic contrast features can fight the charts, disable them when evaluating. Use neighboring DeviceHub tone tools to confirm shadows and highlights after gamma changes. Stepped and continuous grays plus reference imagery illustrate what crushed versus bleached midtones often look like. The tool does not write GPU calibration LUTs and does not upload your brightness clicks. Dynamic contrast and auto-dimming fight charts, disable them while evaluating. After gamma-ish preset changes, neighboring DeviceHub tone tools confirm you did not clip shadows or highlights to “fix” midtones. Labels are guides for human scanning, not machine-vision scored patches. Think of the page as a shared vocabulary for “too heavy” versus “too milky” midtones on a support call, not as an automatic LUT writer.

When to use it

Run Gamma Test after installing ICC profiles, after TV picture-mode changes, when photos look too heavy or washed, and when Black Level Test already showed crushed shadows. Prefer Gradient Test for posterization. Prefer Color Test for hue casts. Prefer HDR Test when asking whether the browser thinks HDR-like media queries are active, not for nits measurement. Run Gamma Test after ICC installs, after TV picture-mode experiments, when JPEGs look too heavy or anemic, and when Black Level Test already showed crushed shadows that tempt you to raise brightness indiscriminately. Prefer Gradient Test for posterization; prefer Color Test for green/magenta casts; prefer HDR Test only when asking whether the browser exposes HDR-ish media queries, not for nits. Classroom projectors that look foggy at default settings often need a gamma preset pass before anyone replaces bulbs. Photographers traveling with a laptop can re-baseline hotel monitors before emergency edits, with eyes open about unmanaged browser limits.

How it works

Patterns are images or canvas/CSS gradients rendered through the normal web pipeline. Perceived gamma depends on luminance, surround lighting, and panel tone curves. No permission prompts. This cannot certify DICOM or broadcast gamma. Remote desktops recompress ramps badly, judge locally. Patterns are images or canvas/CSS gradients rendered through the normal web pipeline; perceived gamma depends on luminance, surround lighting, and the panel’s tone curve. No permission prompts appear. This cannot certify medical display gamma or HDR PQ tracking. Remote desktops recompress ramps into false steps, judge locally. VA glow and IPS glow affect near-black patches differently, which is why Black Level Test remains a sibling rather than a duplicate of gamma charts. SDR charts inside an HDR OS session may be tone-mapped unpredictably; fall back to SDR when classic gamma judgment is the goal. Surround lighting changes perceived mid gray dramatically; a desk lamp behind the viewer can make a correct chart look crushed until you dim that flare source.

Step-by-step instructions

1. Dim specular glare, open Gamma Test fullscreen on the target display, and start with the manufacturer’s standard or sRGB-like picture mode if available.
2. Study gray ramps and reference patches, noting whether mid grays collapse into black or look bleached.
3. Adjust brightness or gamma presets one click at a time, rechecking charts after each change.
4. Confirm shadows with Black Level Test and highlights with White Level Test so gamma tweaks did not clip ends.
5. If banding appears, open Gradient Test; if HDR confuses the chart, fall back to SDR and use HDR Test only for capability hints.
6. Exit when finished; no permission revoke is needed.

Common problems

Bright rooms destroy shadow judgment. Phone photos of gamma charts lie. HDR automatic tone mapping fights SDR charts. Expecting a single “correct” browser gamma across Safari and Chrome ignores color-management differences. VA glow and IPS glow affect near-black patches differently, use Black Level Test too. Bright rooms destroy shadow and midtone judgment alike. Phone photos of gamma charts lie through auto-HDR. Expecting identical “correct” browser gamma across engines ignores color-management differences, document the browser. HDR automatic mapping fighting SDR charts is a workflow error, not proof the panel lacks midtones. One click of dynamic contrast can undo ten careful gamma observations, watch for pumping.

Privacy explanation

Charts render locally. DeviceHub does not store your gamma preferences. No camera access is requested. Closing the tab ends the session UI. Charts render locally; DeviceHub does not store gamma preferences as an account profile. No camera access is requested. Closing the tab ends the session UI without a privilege revoke step. Keep personal photos off shared screenshots of the charts when you capture before-and-after brightness changes for a ticket. Classroom projectors that look milky under fluorescent lights often improve after a gamma preset change verified on these charts, then confirmed with Black Level Test so shadows did not disappear. Keep a short before-and-after note of picture mode names rather than vague “fixed it” comments when handing a lounge TV back to facilities. If midtones look correct but skies still posterize, continue to Gradient Test, gamma and banding are related complaints that need different patterns to separate.