docorient 0.4.1

Document image orientation detection and correction.

docorient

Document image orientation detection and correction.

Automatically detects and fixes rotation (0°, 90°, 180°, 270°) in scanned document images using a two-stage pipeline: energy-based axis detection + neural network flip classification. Achieves 98% accuracy across all four orientations. Includes multi-page majority voting and parallel batch processing.

No external binary dependencies — the neural model ships embedded in the package (~8.5 MB).

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Installation

pip install docorient

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Quick Start

Detect orientation

from PIL import Image
from docorient import detect_orientation

image = Image.open("document.jpg")
result = detect_orientation(image)

print(result.angle)    # 0, 90, 180, or 270
print(result.reliable) # True

Correct a single image

from docorient import correct_image

corrected = correct_image(image)
corrected.save("fixed.jpg")

Correct with metadata

from docorient import correct_image

result = correct_image(image, return_metadata=True)
print(result.orientation.angle)
result.image.save("fixed.jpg")

Correct a multi-page document (majority voting)

from docorient import correct_document_pages
from PIL import Image

pages = [Image.open(f"page_{i}.jpg") for i in range(5)]
results = correct_document_pages(pages)

for i, result in enumerate(results):
    result.image.save(f"fixed_{i}.jpg")

Batch process a directory

macOS / Windows: process_directory uses multiprocessing internally. Always call it inside if __name__ == "__main__": when running as a script.

from docorient import process_directory, OrientationConfig

if __name__ == "__main__":
    config = OrientationConfig(workers=4, output_quality=95)
    summary = process_directory("./scans", output_dir="./fixed", config=config)

    print(f"Corrected: {summary.corrected}/{summary.total_pages}")
    print(f"Errors:    {summary.errors}")

CLI

docorient ./scans --output ./fixed
docorient ./scans --output ./fixed --workers 4 --quality 95
docorient ./scans --limit 100
docorient ./scans --dry-run
docorient --version

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How It Works

DocOrient uses a two-stage detection pipeline:

1. PrimaryEngine — Analyzes horizontal and vertical energy distribution to determine if text is horizontal (0°/180°) or vertical (90°/270°). Fast, pure NumPy, ~97% accurate for axis detection.

2. FlipClassifierEngine — A MobileNetV2-based neural network (exported as ONNX, ~8.5 MB) that classifies whether a document is upside-down (180°). Trained on 3,000+ diverse document images from 5 public datasets (forms, invoices, receipts, technical documents, varied layouts). Achieves 96.8% standalone accuracy. Runs via ONNX Runtime at ~5ms per image on CPU.

The pipeline combines both: PrimaryEngine detects the axis, FlipClassifier resolves the ambiguity within each axis pair (0 vs 180, 90 vs 270). Combined pipeline accuracy: 98% across all four orientations (~20ms per image).

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Configuration Reference

from docorient import OrientationConfig

config = OrientationConfig(
    flip_confidence_threshold=0.50,  # CNN confidence threshold (default: 0.50)
    output_quality=92,               # JPEG output quality 1-100 (default: 92)
    primary_max_dimension=800,       # Max image size for primary engine (default: 800)
    workers=4,                       # Parallel workers; None = cpu_count-2 (default: None)
    resume_enabled=True,             # Resume interrupted batch jobs (default: True)
    supported_extensions=(           # File extensions to process
        ".jpg", ".jpeg", ".png",
        ".tiff", ".tif", ".bmp",
        ".gif", ".webp",
    ),
)

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API Reference

detect_orientation(image, config=None) -> OrientationResult

Detects the orientation of a document image without modifying it.

Parameter	Type	Description
image	PIL.Image.Image	Image to analyze
config	OrientationConfig | None	Configuration (uses defaults if None)

Returns OrientationResult:

Field	Type	Description
angle	int	Detected angle: 0, 90, 180, or 270
method	str	Internal detection trace
reliable	bool	Whether the detection is considered reliable

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correct_image(image, *, config=None, return_metadata=False)

Detects and corrects the orientation of a single image.

• return_metadata=False -> returns PIL.Image.Image
• return_metadata=True -> returns CorrectionResult

CorrectionResult fields: image: PIL.Image.Image, orientation: OrientationResult

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correct_document_pages(pages, *, config=None) -> list[CorrectionResult]

Corrects orientation for all pages of a multi-page document with majority voting.

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process_directory(input_dir, *, output_dir=None, config=None, limit=0, show_progress=True) -> BatchSummary

Processes all images in a directory in parallel.

BatchSummary fields:

Field	Type	Description
input_directory	str	Resolved input path
output_directory	str	Resolved output path
total_files	int	Number of source documents
total_pages	int	Total images processed
already_correct	int	Pages at 0° (no correction needed)
corrected	int	Pages that were rotated
corrected_by_majority	int	Pages corrected via majority voting
errors	int	Pages that failed
pages	tuple[PageResult, ...]	Per-page results

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Multi-page Document Grouping

process_directory automatically groups images by source document using the filename pattern <name>_p<number>.<ext>:

contrato_p1.jpg  ┐
contrato_p2.jpg  ├── grouped as "contrato" -> majority voting applied
contrato_p3.jpg  ┘

edital_p1.jpg    ┐
edital_p2.jpg    ┘── grouped as "edital"

Files that don't match the pattern are treated as single-page documents.

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Supported Formats

Any format readable by Pillow: JPEG, PNG, TIFF, BMP, GIF, WebP, and more.

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Resume Support

Long batch jobs can be safely interrupted with Ctrl+C. Progress is saved to a _orientation_done.log file in the output directory. Re-running resumes from where it stopped.

To disable: OrientationConfig(resume_enabled=False)

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Exceptions

from docorient import (
    DocorientError,
    DetectionError,
    CorrectionError,
    BatchProcessingError,
)

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Development

git clone https://github.com/lucasleirbag/DocOrient.git
cd DocOrient
python -m venv .venv && source .venv/bin/activate
pip install -e ".[dev]"
pytest tests/ -v
ruff check src/ tests/

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License

MIT — see LICENSE