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| 1 |
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| 1 |
+
---
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| 2 |
+
license: mit
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| 3 |
+
language:
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+
- zh
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+
- ko
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+
pipeline_tag: image-to-text
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+
library_name: pytorch
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+
tags:
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+
- ocr
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+
- document-ai
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+
- computer-vision
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- hanja
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| 13 |
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- takbon
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- rubbing
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- resnet
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- hrcenternet
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- google-vision-ocr
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+
---
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| 19 |
+
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+
# EpiText Hanja OCR (Takbon OCR)
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+
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<p align="center">
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🔧 <a href="#google-vision-api-setup-required">Setup</a> |
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▶️ <a href="#running-the-ocr">Run</a> |
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🖼️ <a href="#preprocessing-and-intermediate-outputs">Examples</a> |
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📦 <a href="#final-outputs">Outputs</a>
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</p>
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**Pipeline:** Input → Preprocess (gray for Swin, binary for OCR) → OCR (auto) → JSON + BBox
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| 30 |
+
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+
This repository provides a **damage-aware OCR pipeline specialized for Hanja rubbing (탁본) images**.
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+
The system integrates **Google Vision OCR** with **custom deep learning models** to robustly recognize characters under severe degradation commonly found in stone inscriptions and epigraphic materials.
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+
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---
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| 36 |
+
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+
## Table of Contents
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- [Overview](#overview)
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| 39 |
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- [Requirements](#requirements)
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| 40 |
+
- [Google Vision API Setup](#google-vision-api-setup-required)
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| 41 |
+
- [Running the OCR](#running-the-ocr)
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- [Preprocessing and Intermediate Outputs](#preprocessing-and-intermediate-outputs)
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- [Final Outputs](#final-outputs)
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- [Why Specialized for Takbon](#why-this-ocr-is-specialized-for-rubbing-takbon-images)
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- [License](#license)
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- [Citation](#citation)
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---
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## Overview
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Hanja rubbing images differ significantly from modern scanned documents.
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They often exhibit erosion, ink bleeding, uneven backgrounds, and partially or fully missing characters.
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To address these challenges, this project combines:
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- Custom OCR models optimized for degraded inscription images
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- Explicit modeling of character damage
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- Layout-aware processing for vertical writing
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- Auxiliary use of Google Vision OCR for complementary recognition
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> ⚠️ **Google Vision OCR is not redistributed.**
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> Users must provide their own Google Cloud API credentials.
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---
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## Features
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- OCR ensemble: Google Vision OCR + custom OCR models
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- Damage-aware character tokens: `[MASK1]`, `[MASK2]`
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- Column-wise output for vertically written inscriptions
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- Structured JSON OCR output
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- Bounding box visualization for inspection
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- Fully automated preprocessing → OCR pipeline
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---
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## Repository Structure
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```text
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EpiText-Hanja-OCR/
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├─ assets/ # README example images
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├─ dong_ocr.py # Main execution script
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├─ ai_modules/ # OCR engine, preprocessing, model definitions
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├─ weights/ # Model weights (and user-provided API key)
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├─ requirements.txt
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└─ README.md
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```
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---
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## Requirements
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- Python 3.9+
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- PyTorch
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- Google Cloud Vision API credentials
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Install dependencies:
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```bash
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pip install -r requirements.txt
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```
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---
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## Google Vision API Setup (Required)
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This project requires a **Google Vision API service account JSON file**.
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### Step 1. Create Google Cloud credentials
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1. Go to **Google Cloud Console**
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2. Create or select a project
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3. Enable **Cloud Vision API**
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4. Create a **Service Account**
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5. Generate and download a **JSON key file**
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---
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### Step 2. Place the JSON file in the `weights/` directory
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```text
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weights/
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├─ best.pth
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├─ best_5000.pt
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└─ google_key.json
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```
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⚠️ **Do NOT upload this JSON file to GitHub or Hugging Face.**
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It must remain local to your machine.
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---
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### Step 3. Set environment variables
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#### Linux / macOS
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```bash
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export OCR_WEIGHTS_BASE_PATH=./weights
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export GOOGLE_CREDENTIALS_JSON=google_key.json
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```
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#### Windows (PowerShell)
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```powershell
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$env:OCR_WEIGHTS_BASE_PATH=".\weights"
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$env:GOOGLE_CREDENTIALS_JSON="google_key.json"
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```
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---
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## Running the OCR
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```bash
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python dong_ocr.py path/to/image.jpg
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```
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Example:
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```bash
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python dong_ocr.py assets/input.jpg
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```
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---
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## Preprocessing and Intermediate Outputs
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Before OCR inference, the input image is automatically preprocessed to generate
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task-specific intermediate representations.
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### Preprocessing Examples
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<table>
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<tr>
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<td align="center">
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<strong>Input Image<br>(Rubbing / Takbon)</strong><br>
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<img src="assets/input.jpg" width="250">
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</td>
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<td align="center">
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<strong>Grayscale Image<br>(Swin Input)</strong><br>
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<img src="assets/gray.jpg" width="250">
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</td>
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<td align="center">
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<strong>Binarized Image<br>(OCR Input)</strong><br>
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<img src="assets/binary.png" width="250">
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</td>
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</tr>
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</table>
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---
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## Automatic OCR Pipeline Integration
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The binarized (black-and-white) image is **automatically forwarded to the OCR engine**.
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- No manual image selection is required
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- OCR always consumes the internally generated binary image
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- Preprocessing and OCR are fully coupled for reproducibility
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> **Input image → preprocessing → binary image → OCR (automatic)**
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---
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## Final Outputs
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- `*_gray.jpg`
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Grayscale image used for Swin Transformer–based processing
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- `*_binary.jpg`
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Binarized image automatically used for OCR inference
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- `*_ocr_result.json`
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Structured OCR results including:
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- bounding boxes
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- recognized text
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- damage type (`TEXT`, `MASK1`, `MASK2`)
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- `*_bbox.jpg`
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Visualization image with colored bounding boxes
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### Bounding Box Visualization Example
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- **Green**: Google Vision OCR
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- **Purple**: Custom OCR (HRCenterNet-based)
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- **Blue**: `[MASK1]` (fully missing characters)
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- **Red**: `[MASK2]` (partially damaged characters)
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<img src="assets/bbox.jpg" width="50%">
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---
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## Why This OCR Is Specialized for Rubbing (Takbon) Images
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- Ink bleeding and stone texture noise
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- Partial or complete stroke erosion
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- Non-uniform contrast
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- Vertically arranged, tightly packed characters
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### Design Choices
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#### 1. Dual Image Representation
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- Grayscale for detection
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- Binarized for OCR
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#### 2. Damage-Aware Modeling
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- `[MASK1]`: fully missing
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- `[MASK2]`: partially damaged
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#### 3. Layout Preservation
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- Column-wise processing
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- Correct reading order reconstruction
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#### 4. Auxiliary Google Vision OCR
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- Used as a complementary OCR engine
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- Requires user-provided credentials
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---
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## Model Architecture
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- Text Detection: HRCenterNet-based detector
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- Text Recognition: ResNet-based recognizer
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- Auxiliary OCR: Google Vision OCR
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---
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## Limitations
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- Requires external Google Vision API credentials
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- Performance may degrade under extreme blur
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- Not intended as an end-to-end HF inference widget
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---
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## License
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+
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MIT License
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---
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## Citation
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+
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```bibtex
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@misc{epitext_hanja_ocr_2025,
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title = {EpiText Hanja OCR: Damage-Aware OCR for Rubbing Images},
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author = {donghyun95},
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year = {2025},
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howpublished = {Hugging Face Model Repository}
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}
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```
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