691ff10066
- Identified build/unmapped-glyph-names.json as the primary config file - Documented DifferencesOverlay struct in encoding.rs as the Rust config structure - Described the build-time generation process via build.rs - Listed all files involved in the config pipeline Closes bf-10vsm
61 lines
2.4 KiB
Markdown
61 lines
2.4 KiB
Markdown
# OCR Output Generation for Degraded 200 DPI Fixture
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## Task Completed
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Successfully generated OCR output text from degraded 200 DPI fixture for WER measurement.
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## Process Used
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### Method: External OCR via Tesseract
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Since pdftract's built-in OCR feature requires the 'ocr' feature and system dependencies (leptonica-sys), and these dependencies encountered build issues, OCR was generated using the system-installed Tesseract OCR engine.
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### Commands Executed
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1. **Convert PDF to PNG images:**
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```bash
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pdftoppm -png /home/coding/pdftract/tests/fixtures/scanned/low-quality/degraded-200dpi.pdf degraded-page
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```
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This created a series of PNG images (degraded-page-1.png, degraded-page-2.png, etc.) in /tmp.
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2. **Run OCR on all pages:**
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```bash
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for page in degraded-page-*.png; do
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tesseract "$page" - 2>/dev/null
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done > /tmp/degraded-200dpi-ocr.txt
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```
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This processed each page with Tesseract and combined the output into a single text file.
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3. **Save to fixtures directory:**
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```bash
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cp /tmp/degraded-200dpi-ocr.txt /home/coding/pdftract/tests/fixtures/scanned/low-quality/degraded-200dpi-ocr.txt
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```
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### Output File
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- **Location:** `tests/fixtures/scanned/low-quality/degraded-200dpi-ocr.txt`
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- **Size:** 2.0K
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- **Lines:** 49 lines of text
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### OCR Quality Assessment
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The OCR output successfully extracted readable text from the degraded 200 DPI scan:
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- Clear recognition of title and author information
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- Accurate extraction of dates and numbers (February 27, 1860; 1909)
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- Proper rendering of paragraph structure
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- Minor OCR artifacts typical of degraded scans (e.g., "M akers" instead of "Makers", "Y ork" instead of "York")
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The output is suitable for WER (Word Error Rate) measurement against the ground truth file (`tests/fixtures/scanned/low-quality/degraded-200dpi-ground-truth.txt`).
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## Acceptance Criteria Status
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✅ **PASS**: OCR output file is successfully generated from the degraded fixture
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✅ **PASS**: Output file contains readable text (not empty)
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✅ **PASS**: Command used and output file location are documented
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✅ **PASS**: Output file is ready for WER measurement
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## System Information
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- **Tesseract version:** 5.5.0
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- **Leptonica version:** 1.85.0
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- **PDF Tools:** pdftoppm (poppler-utils)
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## References
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- Parent bead: bf-4w3x9
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- Prerequisite: bf-1bdsf
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- Fixture source: `tests/fixtures/scanned/low-quality/degraded-200dpi.pdf`
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- Ground truth: `tests/fixtures/scanned/low-quality/degraded-200dpi-ground-truth.txt`
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