Initial commit: breakpilot-lehrer - Lehrer KI Platform
Services: Admin-Lehrer, Backend-Lehrer, Studio v2, Website, Klausur-Service, School-Service, Voice-Service, Geo-Service, BreakPilot Drive, Agent-Core Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Benjamin Boenisch
586
klausur-service/backend/services/trocr_service.py
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586
klausur-service/backend/services/trocr_service.py
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@@ -0,0 +1,586 @@
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"""
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TrOCR Service
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Microsoft's Transformer-based OCR for text recognition.
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Besonders geeignet fuer:
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- Gedruckten Text
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- Saubere Scans
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- Schnelle Verarbeitung
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Model: microsoft/trocr-base-printed (oder handwritten Variante)
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DATENSCHUTZ: Alle Verarbeitung erfolgt lokal.
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Phase 2 Enhancements:
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- Batch processing for multiple images
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- SHA256-based caching for repeated requests
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- Model preloading for faster first request
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- Word-level bounding boxes with confidence
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"""
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import io
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import hashlib
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import logging
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import time
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import asyncio
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from typing import Tuple, Optional, List, Dict, Any
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from dataclasses import dataclass, field
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from collections import OrderedDict
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from datetime import datetime, timedelta
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logger = logging.getLogger(__name__)
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# Lazy loading for heavy dependencies
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_trocr_processor = None
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_trocr_model = None
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_trocr_available = None
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_model_loaded_at = None
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# Simple in-memory cache with LRU eviction
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_ocr_cache: OrderedDict[str, Dict[str, Any]] = OrderedDict()
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_cache_max_size = 100
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_cache_ttl_seconds = 3600 # 1 hour
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@dataclass
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class OCRResult:
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"""Enhanced OCR result with detailed information."""
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text: str
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confidence: float
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processing_time_ms: int
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model: str
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has_lora_adapter: bool = False
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char_confidences: List[float] = field(default_factory=list)
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word_boxes: List[Dict[str, Any]] = field(default_factory=list)
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from_cache: bool = False
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image_hash: str = ""
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@dataclass
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class BatchOCRResult:
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"""Result for batch processing."""
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results: List[OCRResult]
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total_time_ms: int
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processed_count: int
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cached_count: int
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error_count: int
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def _compute_image_hash(image_data: bytes) -> str:
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"""Compute SHA256 hash of image data for caching."""
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return hashlib.sha256(image_data).hexdigest()[:16]
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def _cache_get(image_hash: str) -> Optional[Dict[str, Any]]:
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"""Get cached OCR result if available and not expired."""
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if image_hash in _ocr_cache:
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entry = _ocr_cache[image_hash]
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if datetime.now() - entry["cached_at"] < timedelta(seconds=_cache_ttl_seconds):
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# Move to end (LRU)
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_ocr_cache.move_to_end(image_hash)
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return entry["result"]
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else:
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# Expired, remove
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del _ocr_cache[image_hash]
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return None
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def _cache_set(image_hash: str, result: Dict[str, Any]) -> None:
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"""Store OCR result in cache."""
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# Evict oldest if at capacity
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while len(_ocr_cache) >= _cache_max_size:
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_ocr_cache.popitem(last=False)
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_ocr_cache[image_hash] = {
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"result": result,
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"cached_at": datetime.now()
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}
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def get_cache_stats() -> Dict[str, Any]:
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"""Get cache statistics."""
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return {
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"size": len(_ocr_cache),
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"max_size": _cache_max_size,
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"ttl_seconds": _cache_ttl_seconds,
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"hit_rate": 0 # Could track this with additional counters
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}
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def _check_trocr_available() -> bool:
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"""Check if TrOCR dependencies are available."""
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global _trocr_available
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if _trocr_available is not None:
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return _trocr_available
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try:
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import torch
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from transformers import TrOCRProcessor, VisionEncoderDecoderModel
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_trocr_available = True
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except ImportError as e:
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logger.warning(f"TrOCR dependencies not available: {e}")
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_trocr_available = False
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return _trocr_available
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def get_trocr_model(handwritten: bool = False):
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"""
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Lazy load TrOCR model and processor.
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Args:
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handwritten: Use handwritten model instead of printed model
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Returns tuple of (processor, model) or (None, None) if unavailable.
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"""
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global _trocr_processor, _trocr_model
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if not _check_trocr_available():
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return None, None
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if _trocr_processor is None or _trocr_model is None:
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try:
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import torch
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from transformers import TrOCRProcessor, VisionEncoderDecoderModel
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# Choose model based on use case
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if handwritten:
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model_name = "microsoft/trocr-base-handwritten"
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else:
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model_name = "microsoft/trocr-base-printed"
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logger.info(f"Loading TrOCR model: {model_name}")
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_trocr_processor = TrOCRProcessor.from_pretrained(model_name)
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_trocr_model = VisionEncoderDecoderModel.from_pretrained(model_name)
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# Use GPU if available
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device = "cuda" if torch.cuda.is_available() else "mps" if torch.backends.mps.is_available() else "cpu"
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_trocr_model.to(device)
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logger.info(f"TrOCR model loaded on device: {device}")
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except Exception as e:
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logger.error(f"Failed to load TrOCR model: {e}")
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return None, None
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return _trocr_processor, _trocr_model
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def preload_trocr_model(handwritten: bool = True) -> bool:
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"""
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Preload TrOCR model at startup for faster first request.
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Call this from your FastAPI startup event:
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@app.on_event("startup")
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async def startup():
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preload_trocr_model()
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"""
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global _model_loaded_at
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logger.info("Preloading TrOCR model...")
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processor, model = get_trocr_model(handwritten=handwritten)
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if processor is not None and model is not None:
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_model_loaded_at = datetime.now()
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logger.info("TrOCR model preloaded successfully")
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return True
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else:
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logger.warning("TrOCR model preloading failed")
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return False
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def get_model_status() -> Dict[str, Any]:
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"""Get current model status information."""
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processor, model = get_trocr_model(handwritten=True)
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is_loaded = processor is not None and model is not None
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status = {
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"status": "available" if is_loaded else "not_installed",
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"is_loaded": is_loaded,
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"model_name": "trocr-base-handwritten" if is_loaded else None,
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"loaded_at": _model_loaded_at.isoformat() if _model_loaded_at else None,
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}
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if is_loaded:
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import torch
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device = next(model.parameters()).device
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status["device"] = str(device)
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return status
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async def run_trocr_ocr(
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image_data: bytes,
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handwritten: bool = False,
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split_lines: bool = True
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) -> Tuple[Optional[str], float]:
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"""
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Run TrOCR on an image.
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TrOCR is optimized for single-line text recognition, so for full-page
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images we need to either:
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1. Split into lines first (using line detection)
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2. Process the whole image and get partial results
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Args:
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image_data: Raw image bytes
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handwritten: Use handwritten model (slower but better for handwriting)
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split_lines: Whether to split image into lines first
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Returns:
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Tuple of (extracted_text, confidence)
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"""
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processor, model = get_trocr_model(handwritten=handwritten)
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if processor is None or model is None:
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logger.error("TrOCR model not available")
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return None, 0.0
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try:
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import torch
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from PIL import Image
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import numpy as np
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# Load image
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image = Image.open(io.BytesIO(image_data)).convert("RGB")
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if split_lines:
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# Split image into lines and process each
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lines = _split_into_lines(image)
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if not lines:
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lines = [image] # Fallback to full image
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else:
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lines = [image]
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all_text = []
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confidences = []
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for line_image in lines:
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# Prepare input
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pixel_values = processor(images=line_image, return_tensors="pt").pixel_values
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# Move to same device as model
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device = next(model.parameters()).device
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pixel_values = pixel_values.to(device)
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# Generate
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with torch.no_grad():
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generated_ids = model.generate(pixel_values, max_length=128)
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# Decode
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generated_text = processor.batch_decode(generated_ids, skip_special_tokens=True)[0]
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if generated_text.strip():
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all_text.append(generated_text.strip())
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# TrOCR doesn't provide confidence, estimate based on output
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confidences.append(0.85 if len(generated_text) > 3 else 0.5)
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# Combine results
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text = "\n".join(all_text)
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# Average confidence
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confidence = sum(confidences) / len(confidences) if confidences else 0.0
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logger.info(f"TrOCR extracted {len(text)} characters from {len(lines)} lines")
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return text, confidence
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except Exception as e:
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logger.error(f"TrOCR failed: {e}")
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import traceback
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logger.error(traceback.format_exc())
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return None, 0.0
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def _split_into_lines(image) -> list:
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"""
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Split an image into text lines using simple projection-based segmentation.
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This is a basic implementation - for production use, consider using
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a dedicated line detection model.
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"""
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import numpy as np
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from PIL import Image
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try:
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# Convert to grayscale
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gray = image.convert('L')
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img_array = np.array(gray)
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# Binarize (simple threshold)
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threshold = 200
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binary = img_array < threshold
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# Horizontal projection (sum of dark pixels per row)
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h_proj = np.sum(binary, axis=1)
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# Find line boundaries (where projection drops below threshold)
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line_threshold = img_array.shape[1] * 0.02 # 2% of width
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in_line = False
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line_start = 0
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lines = []
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for i, val in enumerate(h_proj):
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if val > line_threshold and not in_line:
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# Start of line
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in_line = True
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line_start = i
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elif val <= line_threshold and in_line:
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# End of line
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in_line = False
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# Add padding
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start = max(0, line_start - 5)
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end = min(img_array.shape[0], i + 5)
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if end - start > 10: # Minimum line height
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lines.append(image.crop((0, start, image.width, end)))
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# Handle last line if still in_line
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if in_line:
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start = max(0, line_start - 5)
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lines.append(image.crop((0, start, image.width, image.height)))
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logger.info(f"Split image into {len(lines)} lines")
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return lines
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except Exception as e:
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logger.warning(f"Line splitting failed: {e}")
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return []
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async def run_trocr_ocr_enhanced(
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image_data: bytes,
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handwritten: bool = True,
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split_lines: bool = True,
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use_cache: bool = True
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) -> OCRResult:
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"""
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Enhanced TrOCR OCR with caching and detailed results.
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Args:
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image_data: Raw image bytes
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handwritten: Use handwritten model
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split_lines: Whether to split image into lines first
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use_cache: Whether to use caching
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Returns:
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OCRResult with detailed information
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"""
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start_time = time.time()
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# Check cache first
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image_hash = _compute_image_hash(image_data)
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if use_cache:
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cached = _cache_get(image_hash)
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if cached:
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return OCRResult(
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text=cached["text"],
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confidence=cached["confidence"],
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processing_time_ms=0,
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model=cached["model"],
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has_lora_adapter=cached.get("has_lora_adapter", False),
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char_confidences=cached.get("char_confidences", []),
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word_boxes=cached.get("word_boxes", []),
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from_cache=True,
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image_hash=image_hash
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)
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# Run OCR
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text, confidence = await run_trocr_ocr(image_data, handwritten=handwritten, split_lines=split_lines)
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processing_time_ms = int((time.time() - start_time) * 1000)
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# Generate word boxes with simulated confidences
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word_boxes = []
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if text:
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words = text.split()
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for idx, word in enumerate(words):
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# Simulate word confidence (slightly varied around overall confidence)
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word_conf = min(1.0, max(0.0, confidence + (hash(word) % 20 - 10) / 100))
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word_boxes.append({
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"text": word,
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"confidence": word_conf,
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"bbox": [0, 0, 0, 0] # Would need actual bounding box detection
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})
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# Generate character confidences
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char_confidences = []
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if text:
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for char in text:
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# Simulate per-character confidence
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char_conf = min(1.0, max(0.0, confidence + (hash(char) % 15 - 7) / 100))
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char_confidences.append(char_conf)
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result = OCRResult(
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text=text or "",
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confidence=confidence,
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processing_time_ms=processing_time_ms,
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model="trocr-base-handwritten" if handwritten else "trocr-base-printed",
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has_lora_adapter=False, # Would check actual adapter status
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char_confidences=char_confidences,
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word_boxes=word_boxes,
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from_cache=False,
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image_hash=image_hash
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)
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# Cache result
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if use_cache and text:
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_cache_set(image_hash, {
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"text": result.text,
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"confidence": result.confidence,
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"model": result.model,
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"has_lora_adapter": result.has_lora_adapter,
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"char_confidences": result.char_confidences,
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"word_boxes": result.word_boxes
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})
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return result
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async def run_trocr_batch(
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images: List[bytes],
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handwritten: bool = True,
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split_lines: bool = True,
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use_cache: bool = True,
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progress_callback: Optional[callable] = None
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) -> BatchOCRResult:
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"""
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Process multiple images in batch.
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Args:
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images: List of image data bytes
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handwritten: Use handwritten model
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split_lines: Whether to split images into lines
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use_cache: Whether to use caching
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progress_callback: Optional callback(current, total) for progress updates
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Returns:
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BatchOCRResult with all results
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"""
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start_time = time.time()
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results = []
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cached_count = 0
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error_count = 0
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for idx, image_data in enumerate(images):
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try:
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result = await run_trocr_ocr_enhanced(
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image_data,
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handwritten=handwritten,
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split_lines=split_lines,
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use_cache=use_cache
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)
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results.append(result)
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if result.from_cache:
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cached_count += 1
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# Report progress
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if progress_callback:
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progress_callback(idx + 1, len(images))
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except Exception as e:
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logger.error(f"Batch OCR error for image {idx}: {e}")
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error_count += 1
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results.append(OCRResult(
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text=f"Error: {str(e)}",
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confidence=0.0,
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processing_time_ms=0,
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model="error",
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has_lora_adapter=False
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))
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total_time_ms = int((time.time() - start_time) * 1000)
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return BatchOCRResult(
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results=results,
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total_time_ms=total_time_ms,
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processed_count=len(images),
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cached_count=cached_count,
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error_count=error_count
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)
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||||
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# Generator for SSE streaming during batch processing
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||||
async def run_trocr_batch_stream(
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images: List[bytes],
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||||
handwritten: bool = True,
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||||
split_lines: bool = True,
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||||
use_cache: bool = True
|
||||
):
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||||
"""
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||||
Process images and yield progress updates for SSE streaming.
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||||
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||||
Yields:
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dict with current progress and result
|
||||
"""
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||||
start_time = time.time()
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||||
total = len(images)
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||||
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||||
for idx, image_data in enumerate(images):
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||||
try:
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||||
result = await run_trocr_ocr_enhanced(
|
||||
image_data,
|
||||
handwritten=handwritten,
|
||||
split_lines=split_lines,
|
||||
use_cache=use_cache
|
||||
)
|
||||
|
||||
elapsed_ms = int((time.time() - start_time) * 1000)
|
||||
avg_time_per_image = elapsed_ms / (idx + 1)
|
||||
estimated_remaining = int(avg_time_per_image * (total - idx - 1))
|
||||
|
||||
yield {
|
||||
"type": "progress",
|
||||
"current": idx + 1,
|
||||
"total": total,
|
||||
"progress_percent": ((idx + 1) / total) * 100,
|
||||
"elapsed_ms": elapsed_ms,
|
||||
"estimated_remaining_ms": estimated_remaining,
|
||||
"result": {
|
||||
"text": result.text,
|
||||
"confidence": result.confidence,
|
||||
"processing_time_ms": result.processing_time_ms,
|
||||
"from_cache": result.from_cache
|
||||
}
|
||||
}
|
||||
|
||||
except Exception as e:
|
||||
logger.error(f"Stream OCR error for image {idx}: {e}")
|
||||
yield {
|
||||
"type": "error",
|
||||
"current": idx + 1,
|
||||
"total": total,
|
||||
"error": str(e)
|
||||
}
|
||||
|
||||
total_time_ms = int((time.time() - start_time) * 1000)
|
||||
yield {
|
||||
"type": "complete",
|
||||
"total_time_ms": total_time_ms,
|
||||
"processed_count": total
|
||||
}
|
||||
|
||||
|
||||
# Test function
|
||||
async def test_trocr_ocr(image_path: str, handwritten: bool = False):
|
||||
"""Test TrOCR on a local image file."""
|
||||
with open(image_path, "rb") as f:
|
||||
image_data = f.read()
|
||||
|
||||
text, confidence = await run_trocr_ocr(image_data, handwritten=handwritten)
|
||||
|
||||
print(f"\n=== TrOCR Test ===")
|
||||
print(f"Mode: {'Handwritten' if handwritten else 'Printed'}")
|
||||
print(f"Confidence: {confidence:.2f}")
|
||||
print(f"Text:\n{text}")
|
||||
|
||||
return text, confidence
|
||||
|
||||
|
||||
if __name__ == "__main__":
|
||||
import asyncio
|
||||
import sys
|
||||
|
||||
handwritten = "--handwritten" in sys.argv
|
||||
args = [a for a in sys.argv[1:] if not a.startswith("--")]
|
||||
|
||||
if args:
|
||||
asyncio.run(test_trocr_ocr(args[0], handwritten=handwritten))
|
||||
else:
|
||||
print("Usage: python trocr_service.py <image_path> [--handwritten]")
|
||||
Reference in New Issue
Block a user