Fix the gray that Windows HDR casts over everything.

No. The core gamma fix is pure math and needs no hardware. Night mode, per-monitor white point trims, and the dashboard all work without a meter. A colorimeter is only required for measurement-based calibration and verification.

Both. HDR is where the gray haze is most obvious, so that is where Gloam started. The gamma fix operates inside the HDR signal path. Measured corrections are installed as native Windows MHC2 profiles for the SDR or HDR display association used during the run. SDR displays also get gamma control, night mode, Game Lab, and full calibration.

Three differences. First, the math: Gloam derives its warm white points from the Planckian locus computed against the CIE 1931 observer, models incomplete chromatic adaptation in CAT16 cone space, and blends in linear light where light physically mixes. Night Light is a simple compositor filter that tints without discernment.

Second, composition: Gloam combines gamma and night rendering into one high-precision live ramp, while an installed MHC2 profile remains the compositor-level measured correction. The output coalescer applies the resolved state as one update.

Third, control: Off disables all warmth, Auto follows your configured time or sun position, and Manual holds your chosen warmth now. You can also set fades, a per-application night-mode auto-disable list that drops the warm shift while a chosen app is in the foreground (gamma and calibration stay active), and per-monitor temperature offsets.

Game Lab resolves a saved display intent when a configured game owns the foreground window. It can select gamma, apply a calibrated shadow lift, choose a night policy, hold schedule-derived color steady with Gameplay Lock, and report local signal facts such as HDR state, DXGI color space, bit depth, headroom, and calibration status.

It does not inject into games, hook swap chains, install an overlay, or inspect game memory. The library scanner reads local Steam, Epic, GOG, and Xbox metadata and leaves every discovered title for you to add explicitly.

Any meter supported by ArgyllCMS. The X-Rite i1 Display family and its Calibrite successors are the common path. Use a spectral correction matched to your panel; Gloam's in-app browser downloads .ccss and .ccmx files from the DisplayCAL community database. On QD-OLED and wide-gamut panels this is essential.

For SDR desktop calibration, DisplayCAL is mature and excellent, and Calman is a professional standard for TV and mastering workflows. If those fit your use case, use them.

Gloam's focus is the HDR-native pipeline on Windows 11. Traditional tools apply corrections through the GPU gamma ramp and ICC profiles that the Advanced Color compositor largely ignores when HDR is on. Gloam builds a properly domain-wrapped MHC2 matrix plus PQ-domain tone LUTs, installs them through the association the HDR pipeline reads, and verifies by measuring through the applied profile. It's just a better option for most users using HDR without expensive professional software (though our math is built on the same principles).

The installer keeps itself current. Gloam checks GitHub on launch, downloads new versions in the background as deltas, and applies them silently the next time the app exits or restarts. No re-downloading, no reinstalling, no administrator prompt. Every release is code-signed. The portable build does not auto-update; to upgrade it, replace it with a newer zip.

For the button: use Off when you need exact daylight color, Auto for normal evening use, and Manual when you want warmth immediately regardless of schedule. Start around 2700K for a strong warm mode, then raise it if the screen feels too amber for your room.

For the rendering algorithm: Perceptual (the default) eases the white point partway toward warm, so colors stay close to normal while blue is cut. Accurate (CIE 1931) applies a full-strength black-body white point, colorimetrically exact but strongly warmed and desaturated. Ultra Night (amber) goes furthest, cutting roughly 90% of blue and most of green for maximum circadian protection in the darkest part of the evening; it is not color-accurate. Classic is a traditional photo-style tint.

If you care about the biological effect rather than the look, set a melanopic dose ceiling on the schedule. Gloam then picks the least visible combination of extra warmth and dimming that keeps the screen's melanopic light at or under your target, scored in CAM16-UCS so the change stays perceptually small.

No. Gloam is code-signed; click More info and you will see the verified publisher. That dialog is Microsoft SmartScreen, which also weighs download reputation. New signed apps can show reputation warnings until enough people have installed them. Click More info, then Run anyway. It stops appearing as Gloam gains installs, and it is unrelated to whether the app is signed or safe.

Yes. Gloam is MIT licensed and the source is on GitHub. ArgyllCMS, which Gloam invokes as a separate process for measurement, is AGPL v3. Gloam does not link against it.