tristim

A Rust toolkit for tristimulus colorimetry on Linux/Wayland: drivers for USB display colorimeters, plus a standalone tool that validates how a Wayland compositor actually reproduces color on each display.

tristim has two faces:

• Reusable crates. tristim-driver (the colorimeter hardware layer) and tristim-display (the Wayland test-patch client) are published on crates.io, carry no compositor-specific or tool-specific assumptions, and are designed to be consumed standalone — e.g. by closed-loop display calibration tools.
• A standalone compositor color-validation tool. Point it at a display, let it drive test patches through the compositor's normal client path, and measure what the panel actually emits. It reports where color reproduction is faithful and where it drifts — white point across the brightness range, primaries and gamut, and EOTF/transfer response, for SDR and HDR (PQ / BT.2020 via wp_color_management_v1) alike.

It is compositor-agnostic by design: it asks for colors the way any client would and measures the result, rather than side-channeling into a specific output's scanout. That makes it an independent check on the color behavior a compositor builds — including prism, which consumes these crates from its own prism-tune calibration tool. Any closed-loop calibration lives in the consuming project, not here.

Hardware support

Product line	USB ID	Protocol	Status
Spyder 2024	085c:0a0b	spydX2	tested
SpyderX2	085c:0a0a	spydX2	should work, untested
Original SpyderX	085c:0a00	spydX	untested port
i1Display Pro / ColorMunki Display	0765:5020	i1d3	untested port — covers the OEM rebadges too (NEC SpectraSensor Pro, HP DreamColor, …)

The wire protocols were reverse-engineered by Graeme Gill for ArgyllCMS (spectro/spydX2.c, spectro/spydX.c, spectro/i1d3.c). The drivers here are a Rust rework derived from that code (and licensed GPL-2.0-or-later to match it — see License), though they do not link ArgyllCMS. Untested ports were written without hardware on hand; validation reports are very welcome. See tristim-driver/README.md for details and per-device notes.

Workspace layout

The gather/present split runs through the whole workspace: tools that talk to hardware record facts only (what the compositor advertised, what was negotiated, code-value→measurement samples); interpretation happens downstream against the recorded facts.

• tristim-driver/ — device-generic colorimeter layer; no Wayland dependency. A Colorimeter trait over the supported instruments (open one with open_any()), measurements as device-agnostic absolute-XYZ Samples, per-measurement trust metrics (MeasurementConfidence), an adaptive-exposure primitive for batch loops, and an optional RawDiagnostics capability for sensor characterization.
• tristim-display/ — Wayland layer-shell client that shows solid-color test patches on a chosen output. Every RGB wl_shm buffer format, the full parametric wp_color_management_v1 surface, and an optional centered-window mode for ABL-limited OLED peak measurement. Code values go into the buffer verbatim; the crate is the workspace's authority on which color representations a compositor can be asked for.
• tristim-capture/ — serde schema for capture files: the on-disk contract between the gatherer and the analysis/presentation tools. No heavy deps.
• tristim-color/ — pure color science (color spaces, transfer functions, ICtCp, error metrics) used to interpret captures.
• tristim-analyze/ — turns a capture into a verdict: derives the expected output for each trial from the negotiated color description and scores how far each measurement landed from it.
• tristim-gather/ — capture orchestration shared by the CLI and GUI: drives a colorimeter and a patch surface through format × color-sequence sweeps, reporting progress through an event callback.
• tristim-cli/ — the gatherer binary tristim. Subcommands for output enumeration, one-shot measurement, sensor characterization (characterize, speed, integration), gamut probing, capture sessions, capture analysis (report), and export (export — CGATS .ti3 per trial for the ArgyllCMS/DisplayCAL toolchain, e.g. colprof to build an ICC profile, or flat CSV). tristim help has the full option set.
• tristim-gui/ — graphical front end: capture-setup form, live capture progress, and visualization of analyzed captures (chromaticity field with error vectors, luminance response, aggregate stats). Carries the workspace's heaviest dependency tree (damascene → wgpu/winit); cargo run -p tristim-gui (see its README).

tristim-driver and tristim-display are published on crates.io; the other crates are internal libraries behind the two applications. The applications ship together as one Arch package — see packaging/ for the AUR PKGBUILD (both binaries, the udev rule, and the desktop entry) and the release checklist.

How the tool talks to the compositor

tristim-display is an ordinary Wayland client. It writes code values into a wl_buffer and commits it on a layer-shell surface — exactly the path any application's content takes. For HDR it declares a parametric wp_color_management_v1 description (e.g. PQ + BT.2020 + mastering metadata) so the compositor treats the buffer as already-encoded HDR content.

This is deliberate: the tool measures what the compositor legitimately does with a client's color request, so the resulting characterization is an honest check on the compositor's pipeline rather than a measurement of a bypassed one.

Requirements

• Linux, and a Wayland compositor that implements wlr-layer-shell (wlroots-based compositors and KDE Plasma do; GNOME does not).
• For HDR and color-managed measurements, the compositor must additionally implement wp_color_management_v1. SDR-unmanaged captures work without it.
• A supported colorimeter from the table above.

Installing

On Arch Linux, the tristim AUR package installs both binaries, the udev rule, and the desktop entry — no further setup needed.

Elsewhere, build from source:

cargo build --release -p tristim-cli -p tristim-gui
# binaries land in target/release/{tristim,tristim-gui}

then install the udev rule by hand:

udev rule

The colorimeters are vendor-class USB devices that need explicit access for non-root users. From the repository root:

sudo cp 50-tristim.rules /etc/udev/rules.d/
sudo udevadm control --reload
# unplug + replug the colorimeter

After that the device is accessible to your logged-in user via systemd-logind's uaccess tag — no group membership needed. (The AUR package ships this rule already.)

Affiliation

Unofficial. Not affiliated with, endorsed by, or sponsored by Datacolor or X-Rite. "Spyder", "SpyderX", "SpyderX2", and "Spyder 2024" are Datacolor's trademarks; "i1Display" and "ColorMunki" are X-Rite's. All are referenced here only to identify supported hardware.

License

Dual MIT / Apache-2.0, with one exception: tristim-driver is GPL-2.0-or-later, as it is derived from the ArgyllCMS instrument drivers (Copyright 2006–2014 Graeme W. Gill). Since every binary links the driver, distributed binaries are governed by the GPL.