Inspect whether PNG assets are truly transparent — locally in your browser.
A PNG extension does not prove that an asset has usable transparency. Files can be fully opaque, carry an unused alpha channel, include a white or gray background, or contain a checkerboard baked into their pixels. TrueAlpha inspects both the PNG structure and decoded alpha pixels so asset problems are visible before they reach a game, build pipeline, or design handoff.
TrueAlpha runs entirely in the browser. Images are never uploaded, no account is required, and there is no remote analysis API.
- Batch import by picker or drag and drop, with duplicate, size, type, and batch-limit checks.
- PNG signature, IHDR, bit-depth, color-type, alpha-channel, and
tRNSinspection. - Exact transparent, semi-transparent, and opaque pixel statistics.
- Content bounding box, transparent margins, edge occupancy, corner samples, and boundary color analysis.
- Conservative suspected solid-background and baked-checkerboard heuristics with confidence and reasons.
- White, black, gray, red, green, blue, and checkerboard previews.
- Fit, native-size, zoom, content-box, and transparent-margin preview tools.
- Search, filter, sort, reanalyze, delete, and clear batch controls.
- JSON and CSV reports without embedded source-image data.
- Non-destructive transparent-padding trim with 0, 2, 4, 8, or 16 px retained margin.
- English and Simplified Chinese UI, system-aware dark mode, and manual theme controls.
- Worker-based image analysis so large assets do not monopolize the main interface thread.
The repository includes a GitHub Pages workflow that deploys every push to main. Open the published app at kanadek.github.io/true-alpha.
For an offline-compatible local session:
npm install
npm run dev
- TrueAlpha validates the PNG signature and reads IHDR and transparency-related chunks from the original
ArrayBuffer. - A browser worker decodes the image into RGBA pixels with
createImageBitmapandOffscreenCanvaswhen supported. - The analysis engine counts alpha values, finds non-transparent bounds, samples edges and corners, and runs conservative background heuristics.
- The UI presents independent labels instead of forcing every file into one oversimplified verdict.
The parser does not infer file structure from the extension or from Canvas output alone.
| Label | Meaning |
|---|---|
REAL_TRANSPARENCY |
At least one decoded pixel has alpha below 255. |
FULL_TRANSPARENCY_PRESENT |
At least one decoded pixel has alpha 0. |
ALPHA_CHANNEL_UNUSED |
The structure supports transparency, but all decoded pixels are opaque. |
FULLY_OPAQUE |
No transparent or semi-transparent pixels were found. |
SEMI_TRANSPARENT_PIXELS |
At least one pixel has alpha from 1 through 254. |
EDGE_CONTENT |
Non-transparent content occupies a configured share of the outer edge. |
TRANSPARENT_PADDING |
Meaningful transparent space exists outside the content bounds. |
SUSPECTED_SOLID_BACKGROUND |
Opaque edge and corner samples are dominated by a low-variance color. |
SUSPECTED_BAKED_CHECKERBOARD |
Two similar light or gray colors repeat with checker-like periodicity near the boundary. |
CLEAN_ASSET |
Real transparency is present without a strong solid-background or checkerboard warning. |
Solid-background and baked-checkerboard results are heuristic. They are always shown as Suspected, include a confidence score and reason, and can be false positives. Semi-transparent pixels are not automatically errors: antialiasing, soft edges, glow, and shadows often require them.
- Source files stay in browser memory.
- Analysis is performed locally in your browser.
- TrueAlpha has no server, database, account system, telemetry endpoint, or external image API.
- Reports contain measurements and filenames, never the original image bytes or data URLs.
- The production application makes no image-upload request.
Requirements: Node.js 22 or newer and npm.
npm install
npm run dev
npm run lint
npm run typecheck
npm run test
npm run test:e2eSynthetic test assets are generated in-repository and do not rely on third-party images:
npm run fixturesnpm run build
npm run preview
npm run release:archiveThe production output is written to dist/. The release command creates true-alpha-v0.1.0-static.zip with the static site and deployment instructions. GitHub Actions automatically uses the /true-alpha/ Vite base path for project Pages.
- WebP and AVIF transparency inspection.
- A CLI and reusable npm package.
- Godot, Unity, and GitHub Action asset-acceptance integrations.
These are roadmap items only and are not included in v0.1.0.
Issues and focused pull requests are welcome. Read CONTRIBUTING.md for setup, test, and heuristic-change expectations.
- Solid-background and checkerboard detection is heuristic and cannot guarantee a correct visual interpretation.
- Ordinary pixel art, textile patterns, grids, and deliberately flat borders can resemble a baked checkerboard or solid background.
- Imports are limited to 25 MB per PNG, 100 files per batch, and 32 million decoded pixels per image to bound browser memory use.
- Very large images remain constrained by each browser's decode and canvas limits even though analysis work normally runs off the main thread.
- Color-managed PNGs can be decoded differently across browsers.
- TrueAlpha inspects and trims PNG files. It is not a background-removal or image-editing tool.
- Animated PNG timing and frame-by-frame analysis are outside v0.1.0.
MIT © 2026 TrueAlpha contributors.