A gradient mask had its own tone formula and its own exposure, and both disagreed with the frame's. Before any of this was tidied, the mask ran a smoothstep luma lift with an arbitrary 0.55..1.35 chroma clamp while the frame moved the knots of a four-zone ramp, and the mask's exposure was a stop on sRGB-encoded values while the frame's was a stop on light. Two names, four moves, and the same slider meant different things depending on whether the pixels were inside the shape you drew — the divergence §3.3 of the Android port's compat doc warns about. The maths is one string now (TONE_MATH_SKSL, interpolated by both passes): the ramp the four knots build, the hue-preserving rebuild behind it, the transfer pair, and exposureMove. A mask calls the same functions the frame calls. The rebuild carries the chroma instead of re-scaling it. Lightness takes the curve and the colour rides the difference — the channel differences move by ONE shared scale k, pulled back only where the cube has no room left. The doc's ratio (R_new = R_old * Luma_new / Luma_old) was the old reading and it is exact only while nothing clips: a channel past 1.0 stops being scaled with its neighbours and the hue goes with it. Measured on a flat patch frame, a skin tone at 24.0° came back at 48.0° at HIGHLIGHT +100, a warm white at 37° at 57.4°, and under L = 0.5 the same ratio multiplied a near-black pixel's cast by x30 — colour noise amplified, which is why the 0.55..1.35 clamp was there. The scale is the chroma's own now: over 135 knob combinations on seven colours and five greys, the ramp moves the luma and the hue does not move at all (Δ < 1e-9°). EXPOSURE gets the same treatment, which is what the second half of the request was: the linear domain decides where the luma is going, and the pixel is rebuilt onto it through the same lightMove. The old pass multiplied the three channels in linear light, so +1 EV clipped them by three different amounts: measured on the scratchpad probe, 29.2° of hue drift on a skin tone at +1 EV and 33.3° at +2, against 0.00° here. The stop is applied as a ratio on the pixel's own encoded luma rather than pointed straight at the encoded linear target, which is what makes the knob exactly the identity at 0 EV — the transfer does not commute with the luma weights, so pointing at it brightened a colour by a couple of code values even at zero. A grey is the knob it always was: 128 through +1 EV is 176, the same number the linear per-channel multiply put there, so nothing a user has dialled in moves. Verified: `npx tsc --noEmit` clean, `npm run build` clean. highlight-knee-check now runs EXPOSURE_SKSL for real — compiled with CanvasKit and four pixels pushed through it, agreeing with the twin to a code value on a grey at +1 EV (176), a skin tone at +1 EV and +2 EV, and a shadow at -2 EV; it also pins the hue, the cube, the identity at 0 EV and the black pixel that has no light to move. mask-wb-check compiles the mask pass and pushes the same stops through it: 128 through +1 EV is 176, through -1 EV is 92, +2 EV lands the channel on the ceiling at 255 and holds the hue within 3°. auto-tone-check, preview-match-check, white-level-check, raw-develop-check, half-check and roll-walk-check all pass. Live on the built bundle in a 1440x950 browser: the LIGHT panel's EXPOSURE +1 EV takes the mid grey of a flat patch frame from 0.502 to 0.690 (a stop on light gives 0.686) and moves no patch's hue at -1 EV (Δ 0.00°), and a linear gradient mask's EXPOSURE +1 EV and HIGHLIGHT +100 move the pixels inside the mask (luma 185.9 -> 211.1 and 185.9 -> 197.5) while the corner outside it does not move at all (220.2 -> 220.2), with no console error. Co-authored-by: PenguinHarness <noreply@penguin.local>
RecipesCam
RecipesCam is a camera and photo-editing app built around recipes — reusable
looks that carry a film simulation plus a full set of adjustments. You shoot or
open a photo, dial in a look, and keep it as a recipe you can apply again, share
as a .recipe file, or save to your account.
It ships twice from one repository: a React Native (Expo) app for iOS and
Android, and a self-contained web build under docker/ that runs the same
render pipeline in the browser.
What it does
- Shoot with a recipe applied. Live viewfinder, GPS-tagged captures, and the recipe baked into the saved file.
- Film simulations. Built-in looks — PROVIPES, VELVIPES, CLASSIC CHRIPES, CLASSIC NEGIPES, ASTIPES, ETERNIPES, ACRIPES, B&W HIGH CONTRAST and the LC STREETLIFE pair — each with its own grain and tone curve.
- The full adjustment set. Exposure, contrast, highlights and shadows, saturation, colour temperature, clarity, grain, and an HSL mixer with a colour picker that samples straight off the photo.
- Geometry. Crop to a fixed ratio or free-form, quarter turns, and a straighten ruler, plus printed frames (classic border, retro instant, wall frame portrait/landscape).
- Finishing. Watermark and GPS stamp, EXIF carried through the export, JPEG written with a proper 300 DPI JFIF header.
- On-device upscaling. A Real-ESRGAN pass runs locally when an export asks for more pixels than the source has — no server sees the photo.
- Recipes. Save, favourite, export and import
.recipefiles; the web build keeps them in your account, the phone build also keeps them on device.
The two builds
| Build | Where | Stack |
|---|---|---|
| iOS / Android | repo root | Expo + React Native, @shopify/react-native-skia for the render pipeline, NativeWind for styling |
| Web | docker/ |
Vite + React, CanvasKit (canvaskit-wasm) for the same pipeline, Fastify + SQLite API for accounts and recipes |
The render engine is shared by design: the web build compiles the app's own
src/utils/* and type definitions unchanged, with @shopify/react-native-skia
aliased to a CanvasKit shim (docker/frontend/src/engine/skiaShim.ts). A look
looks the same on both because it is the same code.
Running the web build
cd docker
cp .env.example .env
docker compose up -d --build
# → http://localhost:8090
Photos never leave the browser: grading, framing, watermarking and JPEG
encoding all run in the visitor's tab; the API only stores accounts and recipe
JSON. See docker/README.md for the layout and the proxy setup.
Running the app
npm install
npx expo start # Expo Go / dev client
npx expo run:android # or run:ios for a native build
Repository layout
App.tsx, src/ the Expo app: screens, tool rail, viewfinder, shaders
docker/ the web build (frontend + API + compose file)
frontend/shared/ vendored copies of the app's types and utils
frontend/src/engine/ CanvasKit shim, export engine, super-resolution
docs/ privacy policy
THIRD_PARTY_NOTICES.md licences of the bundled fonts, models and libraries
Licence
See LICENSE and THIRD_PARTY_NOTICES.md.