Lumen

A photo editor where the image is the whole world.

A fast, non-destructive RAW and photo editor for Linux and macOS — a full tone, colour, detail, and local-adjustment pipeline, GPU-accelerated for real-time preview, with a command-palette workflow instead of a wall of panels.

Download Lumen View source on GitHub

The Lumen editing canvas — a photograph filling the screen with a floating adjustment panel — The photo fills the screen; tools are summoned only when you need them.

Keyboard to navigate and command; pointer to manipulate.

The interaction model

Most editors bury your photo under panels, toolbars, and palettes. Lumen inverts that. It is modal, like an editor should be: you live in Browse mode — zoom, pan, toggle before/after — and drop into a tool only for as long as you need it. Press /, type a few letters of what you want, and go.

What it does

Tone & Colour Exposure, contrast, and tone; per-channel and luma curves; HSL colour mixer; shadow/midtone/highlight colour grading; 3D-LUT looks; and channel-weighted monochrome.

White Balance True linear-light, camera-accurate Kelvin/tint correction, seeded from the RAW's as-shot values, with an eyedropper for neutral picks.

Detail & Repair Content-aware healing brush for spots and distractions, plus sharpen, denoise, and defringe for chromatic-aberration cleanup.

Geometry & Lens Crop, rotate, and flip with aspect presets; automatic distortion, TCA, and vignetting correction from EXIF via Lensfun, plus manual perspective.

Local Adjustments Layers with independent adjustments, opacity, and masks — radial, linear-gradient, luminosity-range, colour-range, and free-hand brush, all non-destructive.

Non-destructive Workflow A re-orderable edit graph with unlimited undo/redo, steppable history, reusable presets, autosave, and crash recovery. Your original is never touched.

Formats & Output Reads JPEG, PNG, TIFF, WebP, and camera RAW (Canon, Nikon, Sony, Fujifilm, and more) via LibRaw; exports 8/16-bit with resize and embedded ICC profiles.

Colour Management A floating-point sRGB working space with highlight headroom, and wide-gamut export to Display P3 or Adobe RGB with the matching profile embedded.

Command Palette Fuzzy subsequence matching over every tool, grouped by workflow. A couple of keystrokes is all it takes — no hunting through menus.

Keys

`/`	Command palette
`Ctrl`+`O` · `Ctrl`+`Shift`+`O`	Open image · open project
`Ctrl`+`S`	Save project
`Ctrl`+`Z` · `Ctrl`+`Shift`+`Z`	Undo · redo
`Ctrl`+`Shift`+`C` · `Ctrl`+`Shift`+`V`	Copy · paste settings
`Ctrl`+`0` · `F11`	Reset view · fullscreen

Under the hood

A genuine, non-destructive imaging pipeline. RAW files are demosaiced at 16 bits and carried through a floating-point working space; every edit is a re-orderable node in an edit graph; the full-resolution result is rendered by libvips while your interactive preview runs on the GPU.

Real-time GPU preview

C++20 and Qt 6.7+, rendering through Qt RHI — Metal on macOS, Vulkan/OpenGL on Linux — with GLSL shaders that replicate the pointwise pipeline.

The imaging engine

libvips drives the full-resolution, memory-efficient pipeline and export; LibRaw decodes RAW; lcms2 handles wide-gamut colour management.

A testable core

A UI-free lumen_core library — image pipeline, edit graph, layers, serialization — sits beneath the Qt front-end, so the imaging code is independently unit-tested.

Open source

Released under the Apache License 2.0. Build from source in one command, or grab a self-contained release for your platform.

Download

The quickest way to run Lumen — no compiler, no dependencies, no terminal required. Grab the latest self-contained build for your platform; Qt and the imaging libraries are bundled in.

Linux · AppImage

Download Lumen-x86_64.AppImage from the releases page, then make it executable and run it.

chmod +x Lumen-x86_64.AppImage
./Lumen-x86_64.AppImage

macOS · DMG

Download Lumen.dmg, open it, and drag Lumen to Applications. On first launch, right-click the app and choose Open to get past Gatekeeper — the build is not yet notarised.

Prefer to build it yourself? Clone the repo and run ./install.sh — it installs the imaging libraries and Qt 6.7+, then builds and installs Lumen. Full instructions on GitHub.

Lumen · Apache License 2.0 ← All projects / GitHub