ThumbProof

Inspiration

Creators design at 1280px. Viewers meet the thumbnail at 168px in the suggested rail â or on a TV across the room. Those surfaces never appear in the design tool, so the same failures ship forever: type too small, contrast too low, subject under the duration pill.

The gallery is full of generators. ThumbProof is the pre-upload verification gate.

What it does

1. Paste any YouTube URL (or drop a PNG).
2. Drop 2â4 variants â ranked by what survives delivery, not full-size beauty. Winner first.
3. See the score + true-size delivery wall (sidebar / phone / TV) with the duration pill.
4. Repair: minimum scrim to WCAG 4.5:1 and optional 16:9 punch-in â arithmetic, not a generative model.
5. Download the repaired PNG + measurement JSON.

No upload. No API key. No ML weights. Same image â same fingerprint.

Try it

• Live: https://moscraciunxxx.github.io/thumbproof/
• Repo: https://github.com/moscraciunxxx/thumbproof
• Demo: https://youtu.be/0hisybVjqtA
• Self-test: https://moscraciunxxx.github.io/thumbproof/selftest.html

How we built it

Pure TypeScript classical CV: Stroke Width Transform, Lanczos-3, SSIM, WCAG contrast, spectral residual saliency. Vitest + live selftest (6/6 authored verdicts).

What's next

Batch over a channel export; optional face detector; CLI pre-upload gate for CI.

Built With

• accessibility
• canvas
• computer-vision
• github
• lanczos
• saliency
• ssim
• stroke-width-transform
• typescript
• vite
• vitest
• wcag