Redlamp

Redlamp is a native, open-source RAW photo editor for the Mac, built from scratch in Swift and Metal for Apple Silicon. It is currently at pre-alpha version 0.2.6 and requires macOS 26. Redlamp keeps the panels, sliders and keyboard shortcuts that photographers already know from Lightroom — including panel order, slider names, ranges, defaults and single-key shortcuts — and rebuilds everything underneath as a native, GPU-first application. It is an editor rather than a catalog: it opens folders of photos and keeps edits in small sidecar files right next to the originals. It is aimed at photographers who edit on a Mac and want Lightroom's familiar workflow without a subscription and without a cloud. The application is licensed under MPL-2.0, is free with no subscription, and runs its AI features on device. Lightroom defined how millions of photographers edit, but it is a cross-platform application that does not feel at home on a Mac, and it is tied to a subscription and a cloud. Redlamp was created to keep the workflow photographers already know and rebuild everything underneath as a native, open-source application. The name comes from the darkroom safelight: a red lamp is the one light you can work by without fogging the paper. The stated idea behind the product is that you can see and shape your photo freely, and the original is never harmed. Redlamp is Mac-first: one platform-neutral engine powers the application, with the Mac editor coming first and iPad and iPhone stated to follow from the same engine. Redlamp's Develop module covers the core of a RAW editing workflow: Basic, Tone Curve, Color Mixer, Color Grading, Detail and Effects. It carries over Lightroom Classic's shortcuts as 83 actions on 87 key bindings, and adjustments can be found by name or by the words people use. The command palette, opened with ⌘K, searches every action, every Develop slider and every picker — including white balance, treatment, Base Looks, recipes, Before/After, snapshots and history — with each action's shortcut shown beside it. Choosing a slider or picker does not close the palette; it turns into that control over the photo. Pressing Return shrinks the palette to a slider bar, where the arrow keys step the value, Shift moves ten times as far, Option adjusts more finely, and typing a name and value such as 'exposure 0.7' or 'temp 5600k' sets the slider directly. Moving through a picker previews each choice on the photo before it is applied. Masking is part of the architecture rather than an afterthought. Every edit is a layer: its own adjustments plus a mask built from components that add, subtract and intersect, as in Lightroom. Linear and radial gradients are drawn and adjusted directly on the photo, with 15 local adjustments including Texture, Clarity and Dehaze, a red mask overlay and a full mask list. Masks are evaluated per pixel inside the same GPU kernel, so 16 of them cost well under a millisecond. On the colour side, the pipeline is linear and scene-referred with a proper camera white-balance model. Temperature and Tint use Robertson's method with the camera's matrix. The Color Mixer works in OKLCh so hues move the way the eye expects, colour grading offers 3-way and individual wheels with Blending and Balance, and the tone curve is available in parametric and point modes. Some looks are measured against cameras' own renderings — Standard v3 sits within ΔE 3.26 of the camera's Provia. The Detail panel handles noise and sharpening with awareness of each photo's own noise, read from the DNG or measured from the raw data when the file opens. Luminance and Color noise reduction use Lightroom's controls, sharpening is noise-aware so the photo's grain passes through untouched, and Texture, Clarity and Dehaze are available globally and inside masks. Highlight reconstruction rebuilds clipped photosites. Recipes bring presets, profiles and LUTs into one open format: 39 bundled recipes in eight groups, the ability to type in a Fujifilm-style camera recipe card exactly as it is written, camera controls such as Dynamic Range, Color Chrome and white-balance shift, and import and export of .redrecipe, .cube and HaldCLUT files. A separate Stack workspace offers one-click focus stacking: Redlamp spots a focus bracket in a folder and offers to merge it, and frames are stacked as demosaiced camera RGB before any edit, so every Develop slider still works on the result. Auto, Smooth and Detail strategies are available, along with a depth map and retouching from any frame. Redlamp's own RAW pipeline treats LibRaw purely as an unpacker. Black levels, white balance, demosaicing and colour all happen inside Redlamp, on the GPU. Bayer sensors use the Menon demosaic by directional filtering with a posteriori decision, X-Trans is supported, hot pixels are repaired before demosaicing, and row and column banding is measured in the sensor's masked optical-black margins and subtracted with the black level. DNG gain maps are applied before demosaicing, and photosites that clipped are rebuilt from their bright unclipped neighbours. The demosaiced image is cached as a full mip pyramid so every zoom level samples the right resolution. A single fused Metal kernel applies every per-pixel adjustment, frames are delivered as IOSurfaces without a copy, and rendering never waits on the main thread. Latest-wins scheduling collapses a burst of slider events to the newest one. Responsiveness is a central design goal. Interactive renders at Fit take 0.6 to 3 milliseconds on Apple Silicon, a full 26 MP frame at 1:1 renders in about 13 milliseconds, a full-resolution export render takes 45 milliseconds, and opening a raw file takes 70 to 250 milliseconds; these figures were measured on an Apple M1 Ultra with a Release build. Because rendering and the UI are strictly separated, the interface never waits on the engine, the disk or the GPU. Exports rest between tiles when the Mac runs hot, and previews take priority over exports. AI features run on device, so photos are never uploaded. Edits are saved to small sidecar files next to each photo and the original stays exactly as it was shot, which protects a photographer's archive. Photos are supported in Sony ARW, Canon CR3, Nikon NEF, Fujifilm RAF, Apple ProRAW and Pixel DNG, plus JPEG, HEIC, TIFF and PNG. Concrete workflows follow Lightroom's habits. A photographer can add folders with the plus button, ⌘O or by dropping them on the window; folders are remembered by bookmark, so a folder that is renamed or moved is followed. The filmstrip follows the disk by itself, so photos copied in, deleted, renamed or rewritten appear, leave or update in place. Focus stacks are looked for one folder at a time in the background and remembered. Before and after comparison is available in three layouts and is cached so edits never re-render it, and the histogram can be dragged across to adjust Blacks, Shadows, Exposure, Highlights or Whites. Photographers can apply a recipe, hover to preview it, then adjust its Amount, save the current edit as a recipe with a settings checklist, and import Lightroom develop presets with a report of what came across exactly, approximately or not at all. On-device AI masks include Subject, Background, People and Sky, using Apple Vision's built-in models with nothing to download, plus Objects, Depth Range, and Landscape categories such as water, vegetation, mountains, architecture, ground and snow. Models are listed in Settings with their size and licence, are removed from there too, and photos are never uploaded. Redlamp is free with no subscription, supports development through Ko-fi, and is licensed MPL-2.0, compatible with the App Store, with algorithms implemented clean-room from papers. It is built with Swift and Metal, runs on macOS 26 on Apple Silicon, and is currently a pre-alpha release, with iPad and iPhone to follow from the same engine. It is a single macOS desktop application, not a web service. Redlamp's promise is simple: Lightroom's workflow, native to your Mac, open source. It gives photographers the panels, sliders and shortcuts they already know, renders every change within a frame, keeps edits in sidecar files beside the originals and never touches the raw files themselves, and does all of it without a subscription or a cloud. For Mac photographers who want a fast, native RAW editor built in Swift and Metal, with serious colour science, GPU-first masking, one-click focus stacking and on-device AI masks, Redlamp offers an open, free alternative at the pre-alpha stage of its development.