3dtours
12113088c8
An export larger than the photo came back flat: the model was never shown the
finest detail the photo held. Before it ran, the source was drawn down to
`scale / 4` of its size — floored at half — and only then handed over, on the
reasoning that a four-for-one model reading `target / 4` invents exactly the
destination and a whole photo would waste three quarters of its output. That
holds for a perfect resampler; it is not what this one is. A 2400px photo going
to 4K was fed at 1200px, and detail finer than the feed's own pixel — 1px
stripes, skin, foliage, fabric — was averaged into flat grey before the model
ever saw it. The draw then had that grey to enlarge, and no model can put back
what it was never given.
The feed is now the bitmap itself, read once at its own size: `drawImage(bitmap,
0, 0)`, no intermediate scale, no floor. The model's four-for-one is spent in
the destination draw instead, which reduces to `scale` and keeps what the photo
actually held. That draw also stops defaulting to `low` — it is usually a
reduction by up to four, and `low` would keep one sample in four of what the
model has just drawn.
Measured against the same running stack, a 2400x1800 source exported at 4K with
bands of 1/2/4/8/16px stripes and a patch of per-pixel grain, each band scored
by how it correlates with the pattern the source held at the source's own pixel
pitch (`r` / on-minus-off swing), plus the grain's high-frequency energy:
p1 p2 grain sd secs
before -0.01 / -0.0 0.94 / 204.0 13.9 51.0
after 0.89 / 179.3 0.95 / 214.7 25.3 188.4
hqresize 0.96 / 83.2 0.99 / 125.9 16.1 —
The 1px band went from uncorrelated and flat to 0.89 — the finest detail the
photo has now reaches the file. Grain lands above the plain-resize reference
rather than below it, which is the model enlarging texture instead of a filter
smearing it.
ponytail: the whole photo per tile means 80 tiles for a 2400px source where 20
were enough, so the wasm path (no WebGPU in the test chromium) grew from 51s to
188s for that export. It is the price of the detail and it is paid once per
export, off the critical path; a device with WebGPU, or a smaller source, does
not pay it this way.
Verified on the rebuilt container (BASE=http://localhost:8090):
- sr-detail-probe.cjs, midtone source so the app's tone pipeline cannot clip
the very detail being measured (an earlier all-contrast version of it reported
"grain 0.00" for the model AND for a plain resize — it was measuring the clip)
- superres-test.cjs 32 PASS / 0 FAIL (export sizes, 4K tile seams clean)
- sr-crop-export.cjs 0 FAIL
- npx tsc --noEmit clean.
RecipesCam web — self-contained stack
A Docker-hosted web build of RecipesCam. Everything it needs is in this folder: move it to another machine, run two commands, and the app is up. It does not need the React Native project around it.
cp .env.example .env
docker compose up -d --build
# → http://localhost:8090
What runs where
| Service | Image | Role |
|---|---|---|
frontend |
nginx:1.27-alpine (built by frontend/Dockerfile) |
Static SPA + /api/ reverse proxy |
api |
node:22-slim (built by backend/Dockerfile) |
Accounts + saved recipes, SQLite on ./data |
frontend resolves api through Docker's embedded DNS and proxies /api/* to
it — that is why the API container is named api and why it is not published on
the host. Only ${WEB_PORT:-8090} is exposed.
Photos never leave the browser. The CanvasKit render pipeline (grade, frame, watermarks, JPEG encode) runs in the visitor's tab; the API only stores recipes as JSON.
Layout
docker-compose.yml the stack
.env.example WEB_PORT
data/ SQLite (created on first run, gitignored)
backend/ Fastify + better-sqlite3 API, own Dockerfile
frontend/ Vite + React + CanvasKit SPA, own Dockerfile + nginx.conf
shared/ vendored copies of the app's types + utils (see below)
src/engine/ skiaShim.ts (CanvasKit) + exportEngine.ts (render pipeline)
+ session.ts (localStorage/IndexedDB studio persistence)
Vendored files
frontend/shared/{types/index.ts,utils/*.ts} are byte-identical copies of
src/types/index.ts and ten src/utils/*.ts files from the React Native
project (@shopify/react-native-skia is aliased to src/engine/skiaShim.ts in
vite.config.ts + tsconfig.json, so those files compile unchanged):
cinemaShader colorUtils defaultRecipes exifWrite frameUtils jpegDpi
paramDefs recipeShare skiaImage toneShader.
The landing page needs no CDN: frontend/public/assets/fonts/*.woff2 are the
seven self-hosted faces behind the three font groups the Themes menu offers
(Plus Jakarta Sans / Inter / JetBrains Mono, Fraunces / Be Vietnam Pro /
Courier Prime, Be Vietnam Pro / Space Mono — all SIL OFL, pulled from Google
Fonts, vietnamese + latin + latin-ext subsets), and
frontend/public/assets/samples/s*.jpg are the six placeholder negatives the
film strip, preset tester and QR card show (swap them for real graded stills
whenever we have them). Its one foreign request is the QR image from
api.qrserver.com, which degrades to an empty slot offline.
When the app changes one of them, copy it back in — the renderer is only "parity" for as long as these stay in sync:
cd <repo>/docker/frontend/shared/utils
cp <repo>/src/utils/<name>.ts .
Operations
docker compose logs -f api # API log
docker compose restart api # after backend/src changes (rebuild: --build)
docker compose down # stop; ./data survives
Backup is the ./data folder — that is the whole database.
Checks
curl -s http://localhost:8090/api/health # {"ok":true}
curl -sI http://localhost:8090/ # 200, index.html
Then open the UI, drop a photo in, and confirm the preview shows the picture and
EXPORT downloads a JPEG that opens. The preview going solid black while the
export still reports a plausible size is the one failure mode worth knowing: it
means the CanvasKit GPU surfaces lost their shared GrDirectContext (see
frontend/src/engine/skiaShim.ts), and with no GPU the raster fallback renders
the same pipeline correctly, just slower.