Eric Gullickson
e4336ce9da
fix: extract VIN from noisy OCR via sliding window + char deletion (refs #113 )
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When OCR reads extra characters (e.g. sticker border as 'C', spurious
'Z' insertion), the raw text exceeds 17 chars and the old first-17
trim produced wrong VINs. New strategy tries all 17-char sliding
windows and single/double character deletions, validating each via
check digit. For 'CWVGGNPE2Z4NP069500', this finds the correct VIN
'WVGGNPE24NP069500' (valid check digit) instead of 'CWVGGNPE2Z4NP0695'
(invalid).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com >
2026-02-06 22:00:07 -06:00
Eric Gullickson
6a4c2137f7
fix: resolve VIN OCR scanning failures on all images (refs #113 )
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Root cause: Tesseract fragments VINs into multiple words but candidate
extraction required continuous 17-char sequences, rejecting all results.
Changes:
- Fix candidate extraction to concatenate adjacent OCR fragments
- Disable Tesseract dictionaries (VINs are not dictionary words)
- Set OEM 1 (LSTM engine) for better accuracy
- Add PSM 11 (sparse text) and PSM 13 (raw line) fallback modes
- Add Otsu's thresholding as alternative preprocessing pipeline
- Upscale small images to meet Tesseract's 300 DPI requirement
- Remove incorrect B->8 and S->5 transliterations (valid VIN chars)
- Fix pre-existing test bug in check digit expected value
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com >
2026-02-06 15:57:14 -06:00
Eric Gullickson
54cbd49171
feat: add VIN photo OCR pipeline (refs #67 )
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Implement VIN-specific OCR extraction with optimized preprocessing:
- Add POST /extract/vin endpoint for VIN extraction
- VIN preprocessor: CLAHE, deskew, denoise, adaptive threshold
- VIN validator: check digit validation, OCR error correction (I->1, O->0)
- VIN extractor: PSM modes 6/7/8, character whitelist, alternatives
- Response includes confidence, bounding box, and alternatives
- Unit tests for validator and preprocessor
- Integration tests for VIN extraction endpoint
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com >
2026-02-01 19:31:36 -06:00
