SealGenerator

Synthetic seal and stamp image generator for OCR data augmentation, with pixel-perfect polygon annotations.

Features

• 12 seal templates — round, oval, rectangular in PRC and Taiwan styles
• Curved text layout — characters placed along elliptical arcs with precise polygon annotations
• 11 degradation effects — ink bleeding, fading, rotation, perspective warp, noise, JPEG artifacts, and more
• 4 export formats — PaddleOCR, COCO JSON, YOLO polygon, MMOCR
• YAML-driven configuration — full control over templates, degradation, compositing, and export
• Font alias system — maps logical font names to available fonts with fallback chains
• Bilingual support — synchronized Chinese + English text for international company seals
• Traditional + Simplified Chinese — Taiwan (正體字) and mainland wordlists included

Quick Start

# Install
pip install -e ".[dev]"

# Download free CJK fonts (optional but recommended)
python scripts/download_fonts.py

# Generate 100 seals with default settings
seal-generator generate -n 100 -o ./output

# Generate Taiwan-style seals
seal-generator generate -c configs/examples/taiwan_seals.yaml

# Generate with all formats
seal-generator generate -n 50 -o ./output -f paddleocr -f coco -f yolo

Templates

Template	Style	Description
round_company	PRC	Round company seal with star center
round_star_center	PRC	Star + serial number + title
round_government	PRC	Government seal with large star
oval_company	PRC	Oval company seal
oval_personal	PRC	Oval personal name seal
rect_personal	PRC	Rectangular personal seal
rect_finance	PRC	Rectangular finance seal
round_tw_company	Taiwan	Round seal with center text (印)
rect_tw_personal	Taiwan	Stone seal style, cinnabar red
round_tw_government	Taiwan	Sun emblem (青天白日) center
oval_tw_company	Taiwan	Oval company seal (Traditional Chinese)
round_tw_bilingual	Taiwan	Chinese + English bilingual seal

Configuration

Seals are configured via YAML. Example:

global:
  seed: 42
  num_images: 100
  output_dir: "./output"

templates:
  - name: "round_tw_company"
    weight: 0.5
  - name: "rect_tw_personal"
    weight: 0.3
  - name: "round_tw_bilingual"
    weight: 0.2

degradation:
  enabled: true
  pipeline:
    - name: "ink_bleeding"
      probability: 0.7
      params: { kernel_size: [3, 5], blur_sigma: [0.5, 1.5] }
    - name: "rotation"
      probability: 0.8
      params: { angle: [-15, 15] }

export:
  formats: ["paddleocr", "coco"]

See configs/examples/ for more examples.

Export Formats

Format	Output	Description
PaddleOCR	label.txt	image_path\t[{"transcription": "...", "points": [...]}]
COCO	annotations.json	Standard COCO with segmentation polygons
YOLO	*.txt per image	Normalized polygon coordinates
MMOCR	labels.jsonl	JSON Lines with polygon + text

Project Structure

seal_generator/
├── core/           # Geometry, text layout, canvas, renderer
├── templates/      # 12 seal template definitions
├── degradation/    # 11 image degradation effects
├── compositing/    # Background compositing
├── annotation/     # Polygon types and transforms
├── export/         # PaddleOCR, COCO, YOLO, MMOCR exporters
├── utils/          # Font loading, RNG, I/O
├── config.py       # Pydantic v2 configuration models
├── pipeline.py     # Main orchestrator
└── cli.py          # Click CLI
configs/            # YAML configuration examples
resources/          # Fonts, wordlists, backgrounds
wiki/               # GitHub Wiki documentation
tests/              # pytest test suite

Development

# Install with dev dependencies
pip install -e ".[dev]"

# Run tests
pytest -v

# Lint
ruff check seal_generator/ tests/

License

MIT