image-bridge-toolkit

image-bridge-toolkit provides cache-backed perceptual image fingerprinting and cross-dataset bridge matching designed to handle large scale (50,000+ image) libraries. It finds identical or highly similar images across disparate folders while remaining resilient to scale shifts, aspect ratio changes, heavy compression, and intrusive watermarks.

Key Features

• Per-Directory JSON Caching: Generates and maintains lightweight image_cache.json files within each directory, keyed by filename and modification time (mtime).
• Scale-Invariant Waveform Approximations: Uses 16-float 1D Discrete Cosine Transform (DCT) grayscale histogram vectors to ignore local watermark text spikes and compression artifacts.
• 5-Tier Matching Funnel:
  1. Tier 1 (Bitwise pHash Luma + Color): Generous 64-bit Hamming filtering to eliminate obvious non-matches.
  2. Tier 2 (Histogram Waveform): Euclidean distance on 16 low-frequency DCT coefficients to filter lighting distribution changes.
  3. Tier 3 (LAB Perceptual Metrics): Vector distance across lab_value, lab_hue, lab_chroma, and lab_warmth.
  4. Tier 4 (Spatial Layout Tie-Breaker): 16-point color spatial coordinates down-weighting image outer margins where signatures and borders reside.
  5. Tier 5 (Optional SSIM Direct Comparison): Full structural similarity pixel comparison on top candidate matches.
• Resumable & High Performance: Output streams as .jsonl objects, allowing runs over huge original sets to resume instantly without re-processing.
• Zero-Dependency Fallback: Runs with OpenCV if available for acceleration, or falls back to pure NumPy + Pillow.

Installation

Install via PyPI:

# Minimal installation (NumPy + Pillow)
pip install image-bridge-toolkit

# Recommended installation (includes OpenCV acceleration & progress bars)
pip install "image-bridge-toolkit[all]"

For development:

git clone [https://github.com/akingdom/image_bridge_toolkit.git](https://github.com/akingdom/image_bridge_toolkit.git)
cd image_bridge_toolkit
pip install -e ".[all]"

Usage

1. Build or Update Metadata Caches (imgcache-build)

Walks a root directory, scanning all subdirectories (skipping any directory containing .ignore_subdir), and generates or updates image_cache.json.

# Build cache for a query dataset (e.g., 1,000 watermarked images)
imgcache-build /path/to/thumbnails_set

# Build cache for a target dataset (e.g., 50,000 original images)
imgcache-build /path/to/originals_set

2. Match Datasets (imgmatch-bridge)

Matches images from the query dataset against the target library, generating a bridge mapping file with confidence scores and top candidate lists.

imgmatch-bridge /path/to/thumbnails_set /path/to/originals_set \
    -o bridge_map.jsonl \
    --max-hamming 16 \
    --candidate-threshold 0.03 \
    --direct-compare

Command-Line Options

Cache Integrity & Updating

• mtime Matching: A cached entry is preserved as long as the file's modification time matches the record in image_cache.json.
• Partial Recomputation: If an existing cache entry is missing a newly added metric type (e.g., hist_waveform), only the missing calculation is executed; existing valid metrics are preserved.
• Corrupt Cache Handling: Invalid or unparseable JSON files are automatically caught and rebuilt without interrupting directory traversal.
• Subdirectory Exclusion: Placing a .ignore_subdir marker inside any directory causes the builder and matcher to ignore that folder and all nested subdirectories.

License & Copyright

• Source Code (src/): Licensed under the MIT License.
• Documentation & Branding: Copyright © 2026 Andrew Kingdom. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).
• Translation Permission: Permission is explicitly granted to translate this documentation into other languages, provided that full attribution to Andrew Kingdom is maintained, a direct link to the original repository is included, and no non-linguistic modifications or structural alterations are made to the content.