Initial commit: Logo detection test framework

Add DETR+CLIP based logo detection library and test framework:
- DetectLogosDETR class for logo detection and matching
- Test script with margin-based and multi-ref matching methods
- Data preparation script for test database
- Documentation for API usage and test methodology

README.md

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+# Logo Detection Test Framework
+
+A testing framework for evaluating logo detection accuracy using DETR (DEtection TRansformer) and CLIP (Contrastive Language-Image Pre-training) models.
+
+## Overview
+
+This project provides tools to:
+- Detect logos in images using a fine-tuned DETR model
+- Match detected logos against reference images using CLIP embeddings
+- Evaluate detection accuracy with precision, recall, and F1 metrics
+
+## Architecture
+
+The system uses a two-stage pipeline:
+
+1. **DETR** - Identifies potential logo regions (bounding boxes) in images
+2. **CLIP** - Extracts feature embeddings for each detected region and compares against reference logos
+
+## Installation
+
+Requires Python 3.12+. Uses [uv](https://github.com/astral-sh/uv) for package management.
+
+```bash
+# Install dependencies
+uv sync
+
+# Or using pip
+pip install -r requirements.txt
+```
+
+## Usage
+
+### Prepare Test Data
+
+First, prepare the test database with logo mappings:
+
+```bash
+uv run python prepare_test_data.py
+```
+
+This creates `test_data_mapping.db` with ground truth mappings between test images and logos.
+
+### Run Detection Tests
+
+```bash
+# Basic test with default settings (margin-based matching)
+uv run python test_logo_detection.py
+
+# Test with more logos and custom threshold
+uv run python test_logo_detection.py -n 20 --threshold 0.75
+
+# Use multi-ref matching method
+uv run python test_logo_detection.py --matching-method multi-ref \
+    --refs-per-logo 5 --min-matching-refs 2
+
+# Reproducible test with seed
+uv run python test_logo_detection.py -n 50 --seed 42
+```
+
+### Key Parameters
+
+| Parameter | Default | Description |
+|-----------|---------|-------------|
+| `-n, --num-logos` | 10 | Number of reference logos to sample |
+| `-t, --threshold` | 0.7 | CLIP similarity threshold |
+| `-d, --detr-threshold` | 0.5 | DETR detection confidence threshold |
+| `--matching-method` | margin | Matching method: `margin` or `multi-ref` |
+| `--margin` | 0.05 | Margin over second-best match (margin method) |
+| `--min-matching-refs` | 1 | Min refs that must match (multi-ref method) |
+| `--refs-per-logo` | 3 | Reference images per logo |
+| `-s, --seed` | None | Random seed for reproducibility |
+
+See `--help` for all options.
+
+## Project Structure
+
+```
+logo_test/
+├── logo_detection_detr.py      # Core detection library (DetectLogosDETR class)
+├── test_logo_detection.py      # Test script for accuracy evaluation
+├── prepare_test_data.py        # Script to prepare test database
+├── test_data_mapping.db        # SQLite database with ground truth
+├── reference_logos/            # Reference logo images (not in git)
+├── test_images/                # Test images (not in git)
+├── logo_detection_detr_usage.md        # API usage guide
+└── logo_detection_test_methodology.md  # Test methodology documentation
+```
+
+## Accuracy Improvement Techniques
+
+The framework implements several techniques to improve detection accuracy:
+
+1. **Non-Maximum Suppression (NMS)** - Removes overlapping duplicate detections
+2. **Minimum Box Size Filtering** - Filters out noise from tiny detections
+3. **Confidence Threshold Filtering** - Removes low-confidence detections
+4. **Multiple Reference Images** - Uses multiple refs per logo for robust matching
+5. **Margin-Based Matching** - Requires confidence margin over second-best match
+6. **Multi-Ref Matching** - Aggregates similarity scores across references
+7. **Embedding Caching** - Caches embeddings to avoid recomputation
+
+## Models
+
+The framework uses:
+- **DETR**: `Pravallika6/detr-finetuned-logo-detection_v2`
+- **CLIP**: `openai/clip-vit-large-patch14`
+
+Models are automatically downloaded from HuggingFace on first run and cached in `~/.cache/huggingface/`.
+
+## Documentation
+
+- [API Usage Guide](logo_detection_detr_usage.md) - How to use the DetectLogosDETR class
+- [Test Methodology](logo_detection_test_methodology.md) - Detailed explanation of test framework and tuning
+
+## License
+
+MIT