Erich Blume
33463764d1
Single-file Go tool implementing the QArt technique (Russ Cox, 2012) using only the public rsc.io/qr API. Generates QR codes whose data modules form a recognizable image by exploiting error correction freedom via GF(2) Gaussian elimination. Includes a web UI with live-updating sliders for version, mask, rotation, dx/dy offset, and scale. Keyboard shortcuts for rapid iteration. Also works as a CLI for batch generation. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
61 lines
2.2 KiB
Markdown
61 lines
2.2 KiB
Markdown
---
|
|
title: QArt Tuner
|
|
modified: 2026-03-27
|
|
tags:
|
|
- reference
|
|
- tools
|
|
- utils
|
|
---
|
|
|
|
# QArt Tuner
|
|
|
|
Generates QR codes whose data modules form a recognizable image, using the [QArt technique](https://research.swtch.com/qart) by Russ Cox. Lives in `utils/qart/`.
|
|
|
|
## Quick Reference
|
|
|
|
| Item | Value |
|
|
|------|-------|
|
|
| **Source** | `utils/qart/main.go` |
|
|
| **Language** | Go (managed via mise) |
|
|
| **Dependency** | [rsc.io/qr](https://github.com/rsc/qr) (BSD 3-clause) |
|
|
| **Launch web UI** | `QART_IMAGE=photo.png mise run serve` (from `utils/qart/`) |
|
|
| **CLI** | `mise x go -- go run . -url URL -image IMG -out out.png` |
|
|
|
|
## How It Works
|
|
|
|
QR error correction (Reed-Solomon coding) allows some data and check bits to be freely chosen. The tool:
|
|
|
|
1. Builds a QR code plan for the given URL and version
|
|
2. Converts the source photo to a grayscale brightness grid at QR module resolution
|
|
3. For each ECC block, models the data/check bit relationships as a matrix over GF(2)
|
|
4. Uses Gaussian elimination to find which bits can be independently assigned
|
|
5. Assigns bits to match the target image brightness, prioritizing high-contrast areas
|
|
|
|
The result is a valid, scannable QR code whose black/white modules approximate the source image.
|
|
|
|
## Web UI
|
|
|
|
The interactive tuner (`-serve` flag) provides sliders for all parameters with live preview.
|
|
|
|
**Keyboard shortcuts:** arrow keys (dx/dy offset), `[`/`]` (mask), `-`/`=` (version), `r` (rotate).
|
|
|
|
## Parameters
|
|
|
|
| Parameter | Range | Effect |
|
|
|-----------|-------|--------|
|
|
| **version** | 1-8 | QR density — higher = more modules = finer detail |
|
|
| **mask** | 0-7 | QR mask pattern — dramatically affects which pixels are controllable |
|
|
| **dx/dy** | -15 to 15 | Shifts image relative to QR structure (avoids alignment dot on eyes) |
|
|
| **rotation** | 0-3 | Quarter turns |
|
|
| **scale** | 1-16 | Output pixels per QR module |
|
|
| **dither** | on/off | Floyd-Steinberg dithering |
|
|
|
|
## Credits
|
|
|
|
- **Technique:** [Russ Cox](https://swtch.com/~rsc/), [QArt Codes](https://research.swtch.com/qart) (2012)
|
|
- **QR library:** [rsc.io/qr](https://github.com/rsc/qr) — QR layout, encoding, GF(256) arithmetic
|
|
- **Implementation:** Claude Code (Opus 4.6) with direction from Erich Blume
|
|
|
|
## Related
|
|
|
|
- [[mise-tasks]] — Task runner for BlumeOps operations
|