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+ ---
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+ language:
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+ - en
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+ license: mit
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+ tags:
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+ - handwriting-recognition
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+ - ocr
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+ - computer-vision
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+ - pytorch
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+ - crnn
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+ - ctc
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+ - iam-dataset
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+ library_name: pytorch
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+ datasets:
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+ - Teklia/IAM-line
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+ metrics:
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+ - cer
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+ - wer
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+ ---
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+
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+ # ๐Ÿ–‹๏ธ Handwriting Recognition with Deep Learning
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+
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+ <div align="center">
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+
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+ [![Model](https://img.shields.io/badge/๐Ÿค—%20Model-IsmatS%2Fhandwriting--recognition--iam-blue)](https://huggingface.co/IsmatS/handwriting-recognition-iam)
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+ [![Dataset](https://img.shields.io/badge/๐Ÿค—%20Dataset-Teklia%2FIAM--line-green)](https://huggingface.co/datasets/Teklia/IAM-line)
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+ [![License](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
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+ [![PyTorch](https://img.shields.io/badge/PyTorch-2.0+-red.svg)](https://pytorch.org/)
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+
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+ **A complete end-to-end handwriting recognition system using CNN-BiLSTM-CTC architecture**
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+
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+ [๐ŸŽฏ Model](#-trained-model) โ€ข [๐Ÿ“Š Dataset Analysis](#-dataset-insights) โ€ข [๐Ÿ—๏ธ Architecture](#๏ธ-model-architecture) โ€ข [๐Ÿ“ˆ Performance](#-training-results) โ€ข [๐Ÿš€ Quick Start](#-quick-start)
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+
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+ </div>
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+
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+ ---
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+
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+ ## ๐ŸŽฏ Overview
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+
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+ This project implements a state-of-the-art **Handwriting Recognition** system that converts handwritten text images into digital text. The model achieves **87% character-level accuracy** on the IAM Handwriting Database.
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+
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+ ### Key Highlights
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+
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+ - โœ… **CNN-BiLSTM-CTC Architecture** - Industry-standard OCR architecture
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+ - โœ… **9.1M Parameters** - Efficient yet powerful model
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+ - โœ… **CER: 12.95%** - High character recognition accuracy
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+ - โœ… **IAM Dataset** - 10,000+ handwritten text samples
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+ - โœ… **Google Colab Compatible** - Train on free GPU
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+ - โœ… **Production Ready** - Complete inference pipeline
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+
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+ ---
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+
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+ ## ๐Ÿ”— Resources
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+
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+ | Resource | Link | Description |
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+ |----------|------|-------------|
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+ | **๐Ÿค— Trained Model** | [IsmatS/handwriting-recognition-iam](https://huggingface.co/IsmatS/handwriting-recognition-iam) | Pre-trained weights (105MB) |
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+ | **๐Ÿ“ฆ Dataset** | [Teklia/IAM-line](https://huggingface.co/datasets/Teklia/IAM-line) | IAM Handwriting Database |
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+ | **๐Ÿ““ Training Notebook** | `train_colab.ipynb` | Full training pipeline |
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+ | **๐Ÿ“Š Analysis Notebook** | `analysis.ipynb` | Dataset exploration |
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+
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+ ---
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+
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+ ## ๐Ÿ“Š Dataset Insights
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+
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+ The **IAM Handwriting Database** is one of the most widely-used datasets for handwriting recognition research. Here's what we discovered:
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+
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+ ### Dataset Statistics
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+
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+ | Split | Samples | Usage |
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+ |-------|---------|-------|
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+ | **Train** | 6,482 | Model training |
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+ | **Validation** | 976 | Hyperparameter tuning |
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+ | **Test** | 2,915 | Final evaluation |
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+ | **Total** | 10,373 | Complete dataset |
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+
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+ ### ๐Ÿ“ธ Sample Images
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+
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+ Real handwritten text samples from the dataset:
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+
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+ ![Sample Images](charts/01_sample_images.png)
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+
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+ **Observations:**
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+ - โœ๏ธ Diverse writing styles (cursive, print, mixed)
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+ - ๐Ÿ“ Variable text lengths (10-100+ characters)
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+ - ๐ŸŽจ Different pen types and ink intensity
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+ - ๐Ÿ“ Natural variations in slant and spacing
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+
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+ ---
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+
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+ ### ๐Ÿ“ Text Length Distribution
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+
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+ ![Text Length Distribution](charts/02_text_length_distribution.png)
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+
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+ **Key Insights:**
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+ - ๐Ÿ“Š **Mean length**: ~48-60 characters per line
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+ - ๐Ÿ“ˆ **Peak**: 40-70 character range (most common)
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+ - ๐Ÿ”ข **Range**: 5-150 characters
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+ - ๐ŸŽฏ **Implication**: Model must handle variable-length sequences efficiently
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+
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+ **Why this matters:** The CTC (Connectionist Temporal Classification) loss function in our model is specifically designed to handle this variability without requiring character-level alignment annotations.
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+
103
+ ---
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+
105
+ ### ๐Ÿ“ Image Dimensions Analysis
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+
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+ ![Image Dimensions](charts/03_image_dimensions.png)
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+
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+ **Dimensional Characteristics:**
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+
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+ | Metric | Width | Height | Aspect Ratio |
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+ |--------|-------|--------|--------------|
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+ | **Mean** | ~400-500px | ~50-100px | ~6-8:1 |
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+ | **Min** | ~100px | ~30px | ~3:1 |
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+ | **Max** | ~1200px | ~150px | ~15:1 |
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+
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+ **Engineering Decision:**
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+ - ๐Ÿ”„ **Fixed height**: Resize to 128px (preserves vertical features)
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+ - ๐Ÿ“ **Variable width**: Maintain aspect ratio (prevents distortion)
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+ - ๐ŸŽฏ **Result**: Preserves legibility while standardizing input
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+
122
+ ---
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+
124
+ ### ๐Ÿ”ค Character Frequency Analysis
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+
126
+ ![Character Frequency](charts/04_character_frequency.png)
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+
128
+ **Character Distribution:**
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+ - ๐Ÿ”ก **Lowercase dominates**: 'e', 't', 'a', 'o', 'n' (English frequency)
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+ - ๐Ÿ”  **Capitals less common**: Sentence beginnings, proper nouns
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+ - ๐Ÿ”ข **Numbers rare**: Limited numeric content
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+ - โš™๏ธ **Punctuation**: Periods, commas most frequent
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+
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+ **Implications:**
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+ - ๐Ÿ“š **74 unique characters**: a-z, A-Z, 0-9, space, punctuation
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+ - โš–๏ธ **Class imbalance**: Model sees more common characters
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+ - ๐ŸŽ“ **Training strategy**: No special balancing needed (mirrors real-world text)
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+
139
+ ---
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+
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+ ### ๐Ÿ“‹ Summary Statistics
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+
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+ ![Summary Statistics](charts/05_summary_statistics.png)
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+
145
+ **Complete Statistical Overview:**
146
+ - ๐Ÿ“Š Min/Max/Mean for all features
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+ - ๐Ÿ“ˆ Standard deviations
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+ - ๐ŸŽฏ Quartile distributions
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+ - ๐Ÿ” Outlier detection
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+
151
+ ---
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+
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+ ## ๐Ÿ—๏ธ Model Architecture
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+
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+ Our **CNN-BiLSTM-CTC** architecture combines three powerful components:
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+
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+ ```
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+ Input Image (128 x Variable Width)
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+ โ†“
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+ โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”
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+ โ”‚ CNN Layers โ”‚ โ† Extract visual features
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+ โ”‚ (7 blocks) โ”‚ (edges, strokes, characters)
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+ โ””โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”˜
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+ โ†“
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+ Feature Maps (512 channels)
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+ โ†“
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+ โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”
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+ โ”‚ BiLSTM โ”‚ โ† Model sequential dependencies
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+ โ”‚ (2 layers) โ”‚ (left-to-right + right-to-left)
170
+ โ””โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”˜
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+ โ†“
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+ โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”
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+ โ”‚ CTC Decoder โ”‚ โ† Alignment-free decoding
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+ โ”‚ (75 chars) โ”‚ (handles variable lengths)
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+ โ””โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”˜
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+ โ†“
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+ Predicted Text
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+ ```
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+
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+ ### Component Breakdown
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+
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+ #### 1๏ธโƒฃ **CNN Feature Extractor** (7 Convolutional Blocks)
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+
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+ | Block | Layers | Output Channels | Purpose |
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+ |-------|--------|-----------------|---------|
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+ | 1 | Conv + BN + ReLU + MaxPool | 64 | Basic edge detection |
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+ | 2 | Conv + BN + ReLU + MaxPool | 128 | Stroke patterns |
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+ | 3 | Conv + BN + ReLU | 256 | Character components |
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+ | 4 | Conv + BN + ReLU + MaxPool(2,1) | 256 | Horizontal compression |
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+ | 5 | Conv + BN + ReLU | 512 | Complex features |
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+ | 6 | Conv + BN + ReLU + MaxPool(2,1) | 512 | Further compression |
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+ | 7 | Conv + BN + ReLU | 512 | Final features |
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+
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+ **Key Design Choices:**
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+
196
+ | Design Decision | Rationale |
197
+ |----------------|-----------|
198
+ | **Batch Normalization** | Normalizes activations โ†’ faster training, prevents internal covariate shift |
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+ | **Asymmetric pooling (2,1)** | Compress height but preserve width โ†’ maintains character boundaries |
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+ | **Progressive channels (64โ†’512)** | More filters = richer features at deeper layers |
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+ | **No pooling in Conv 3,5** | Maintains spatial resolution for detail preservation |
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+
203
+ **Why Asymmetric MaxPool (2,1)?**
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+
205
+ ```
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+ Regular MaxPool (2,2):
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+ Image: [128, 400] โ†’ [64, 200] โ†’ [32, 100] โ†’ [16, 50]
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+ Problem: Loses too much horizontal resolution โŒ
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+ Result: Character boundaries blur together
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+
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+ Asymmetric MaxPool (2,1):
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+ Image: [128, 400] โ†’ [64, 400] โ†’ [32, 400] โ†’ [16, 400]
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+ Benefit: Preserves horizontal details โœ…
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+ Result: Each character remains distinct
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+ ```
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+
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+ #### 2๏ธโƒฃ **Bidirectional LSTM** (Sequence Modeling)
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+
219
+ ```
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+ Configuration:
221
+ - Input Size: 256
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+ - Hidden Size: 256
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+ - Num Layers: 2
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+ - Bidirectional: Yes (512 output)
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+ - Dropout: 0.3
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+ ```
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+
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+ **Why BiLSTM?**
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+ - โฌ…๏ธ **Forward pass**: Reads left-to-right (like humans)
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+ - โžก๏ธ **Backward pass**: Reads right-to-left (context from future)
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+ - ๐Ÿ”„ **Combined**: Each character sees full sentence context
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+
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+ #### 3๏ธโƒฃ **CTC Loss** (Alignment-Free Training)
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+
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+ **Advantages:**
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+ - ๐ŸŽฏ No character-level position labels needed
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+ - ๐Ÿ“ Handles variable-length input/output
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+ - ๐Ÿ”„ Learns temporal alignment automatically
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+ - โœ… Industry standard for OCR/speech recognition
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+
241
+ **Total Parameters:** 9,139,147 (~9.1M)
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+
243
+ ---
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+
245
+ ### ๐Ÿ” Deep Dive: How the Model Works
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+
247
+ #### Step-by-Step Processing Pipeline
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+
249
+ **1. Image Input Processing**
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+ ```
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+ Original Image: "Hello" (handwritten)
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+ โ†“
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+ Resize: Height=128px, Width proportional
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+ โ†“
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+ Normalize: Pixel values from [0,255] โ†’ [-1,1]
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+ โ†“
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+ Tensor Shape: [Batch=1, Channels=1, Height=128, Width=W]
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+ ```
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+
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+ **2. CNN Feature Extraction**
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+
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+ The CNN progressively extracts hierarchical visual features:
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+
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+ | Layer Type | What It Detects | Example |
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+ |------------|-----------------|---------|
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+ | **Conv1-2 (64-128 ch)** | Edges, lines, curves | Vertical strokes, horizontal bars |
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+ | **Conv3-4 (256 ch)** | Stroke combinations | Letter parts: tops of 't', loops in 'e' |
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+ | **Conv5-7 (512 ch)** | Character-level features | Distinguish 'o' from 'a', 'n' from 'h' |
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+
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+ **Output:** Feature map of shape `[Batch, 512, 7, W_reduced]`
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+ - Height reduced: 128 โ†’ 7 (18x compression)
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+ - Width reduced: ~W โ†’ W/4 (4x compression)
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+ - Channels increased: 1 โ†’ 512 (rich features)
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+
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+ **3. Sequence-to-Sequence Mapping**
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+
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+ ```python
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+ # Convert 2D feature map to 1D sequence
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+ Feature Map: [B, 512, 7, W/4]
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+ โ†“
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+ Reshape: [B, W/4, 512*7] = [B, W/4, 3584]
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+ โ†“
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+ Linear Layer: [B, W/4, 3584] โ†’ [B, W/4, 256]
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+ ```
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+
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+ Now we have a **temporal sequence** where each time step represents a horizontal segment of the image.
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+
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+ **4. BiLSTM Sequential Modeling**
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+
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+ ```
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+ Time step t:
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+ Forward LSTM โ†’ Reads: "H" "e" "l" "l" "o"
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+ Backward LSTM โ† Reads: "o" "l" "l" "e" "H"
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+ โ†“
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+ Concatenate: [forward_256, backward_256] = 512
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+ โ†“
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+ Context-aware representation for each character
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+ ```
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+
300
+ **Why bidirectional matters:**
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+ - Forward: "H" knows it's at the start of a word
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+ - Backward: "H" knows "ello" comes after it
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+ - Combined: Better prediction accuracy
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+
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+ **5. CTC Decoding**
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+
307
+ ```
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+ LSTM Output: [B, W/4, 512]
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+ โ†“
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+ Linear: [B, W/4, 512] โ†’ [B, W/4, 75] (75 = 74 chars + blank)
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+ โ†“
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+ Softmax: Probability distribution over characters
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+ โ†“
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+ CTC Decode: Remove blanks and duplicates
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+ ```
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+
317
+ **Example CTC Alignment:**
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+ ```
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+ Model output (frame by frame):
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+ [-, -, H, H, H, -, e, e, -, l, l, l, -, l, -, o, o, -, -]
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+
322
+ CTC decoding:
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+ - Remove blanks (-)
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+ - Collapse repeats
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+ Result: "Hello" โœ…
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+ ```
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+
328
+ ---
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+
330
+ ### ๐Ÿ“ Understanding the Metrics
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+
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+ #### **CER (Character Error Rate)**
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+
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+ CER measures the **edit distance** at character level using Levenshtein distance.
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+
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+ **Formula:**
337
+ ```
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+ CER = (Insertions + Deletions + Substitutions) / Total_Characters_in_Ground_Truth
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+ ```
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+
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+ **Example Calculation:**
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+
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+ | Ground Truth | Prediction | Operations | CER |
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+ |--------------|-----------|------------|-----|
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+ | `hello` (5 chars) | `helo` | 1 deletion ('l') | 1/5 = **20%** |
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+ | `hello` (5 chars) | `hallo` | 1 substitution ('e'โ†’'a') | 1/5 = **20%** |
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+ | `hello` (5 chars) | `helloo` | 1 insertion ('o') | 1/6 = **16.7%** |
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+ | `hello` (5 chars) | `hello` | 0 errors | 0/5 = **0%** โœ… |
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+
350
+ **Our Model Performance:**
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+ ```
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+ CER = 12.95%
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+
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+ Example with 100 characters:
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+ - Ground truth: 100 characters
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+ - Errors: ~13 character mistakes
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+ - Correct: ~87 characters โœ…
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+
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+ Character-level accuracy: 87.05%
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+ ```
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+
362
+ **What CER tells us:**
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+ - โœ… Lower is better (0% = perfect)
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+ - โœ… Character-by-character accuracy
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+ - โœ… Sensitive to small mistakes
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+ - โœ… Good for measuring overall quality
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+
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+ ---
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+
370
+ #### **WER (Word Error Rate)**
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+
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+ WER measures the **edit distance** at word level.
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+
374
+ **Formula:**
375
+ ```
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+ WER = (Word_Insertions + Word_Deletions + Word_Substitutions) / Total_Words_in_Ground_Truth
377
+ ```
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+
379
+ **Example Calculation:**
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+
381
+ | Ground Truth | Prediction | Word Errors | WER |
382
+ |--------------|-----------|-------------|-----|
383
+ | `hello world` (2 words) | `helo world` | 1 error ('hello'โ†’'helo') | 1/2 = **50%** |
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+ | `hello world` (2 words) | `hello world` | 0 errors | 0/2 = **0%** โœ… |
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+ | `the quick brown fox` (4 words) | `the quik brown fox` | 1 error ('quick'โ†’'quik') | 1/4 = **25%** |
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+
387
+ **Our Model Performance:**
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+ ```
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+ WER = 42.47%
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+
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+ Example with 100 words:
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+ - Ground truth: 100 words
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+ - Word errors: ~42 words have at least 1 character wrong
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+ - Correct words: ~58 words โœ…
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+
396
+ Word-level accuracy: 57.53%
397
+ ```
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+
399
+ **Why WER > CER?**
400
+
401
+ One character error corrupts the entire word:
402
+
403
+ ```
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+ Ground Truth: "The magnificent castle stood tall"
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+ Prediction: "The magnifcent castle stood tall"
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+ โ†‘ missing 'i'
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+
408
+ Character errors: 1
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+ Word errors: 1 (entire word "magnificent" is wrong)
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+
411
+ CER = 1/34 = 2.9%
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+ WER = 1/5 = 20% โ† Much higher!
413
+ ```
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+
415
+ **What WER tells us:**
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+ - โœ… More strict than CER
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+ - โœ… Real-world usability measure
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+ - โœ… High WER with low CER = mostly correct characters but words incomplete
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+ - โš ๏ธ Can be harsh on OCR systems
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+
421
+ ---
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+
423
+ #### **CTC Loss**
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+
425
+ The loss function used during training.
426
+
427
+ **What is CTC Loss?**
428
+
429
+ Connectionist Temporal Classification (CTC) solves the **alignment problem** in sequence-to-sequence tasks.
430
+
431
+ **The Problem CTC Solves:**
432
+
433
+ Traditional approaches need exact character positions:
434
+ ```
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+ Image: "Hello"
436
+ Required labels:
437
+ - 'H' at pixels 0-20
438
+ - 'e' at pixels 21-35
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+ - 'l' at pixels 36-50
440
+ - 'l' at pixels 51-65
441
+ - 'o' at pixels 66-80
442
+ ```
443
+
444
+ This is **impossible to annotate** for handwriting!
445
+
446
+ **CTC Solution:**
447
+
448
+ Just provide the text: `"Hello"` โœ…
449
+
450
+ CTC figures out the alignment automatically:
451
+
452
+ ```
453
+ Input Frames: |---|---|---|---|---|---|---|---|---|
454
+ Model Output: | - | H | H | e | - | l | l | o | - |
455
+ โ†“ โ†“ โ†“ โ†“ โ†“ โ†“ โ†“ โ†“ โ†“
456
+ CTC Decoding: Remove blanks (-) and collapse repeats
457
+ Result: "Hello" โœ…
458
+ ```
459
+
460
+ **How CTC Training Works:**
461
+
462
+ 1. **Blank token (ฮต)**: Special symbol for "no character"
463
+ 2. **Multiple alignments**: Many ways to align same text
464
+ 3. **Sum probabilities**: CTC sums all valid alignments
465
+
466
+ **Example:**
467
+ ```
468
+ Target: "Hi"
469
+
470
+ Valid alignments:
471
+ - [H, i, -, -]
472
+ - [-, H, i, -]
473
+ - [H, H, i, i]
474
+ - [-, H, -, i]
475
+ ... many more!
476
+
477
+ CTC Loss = -log(sum of probabilities of all valid paths)
478
+ ```
479
+
480
+ **Why CTC is Powerful:**
481
+
482
+ โœ… **No alignment needed**: Just text labels
483
+ โœ… **Handles variable lengths**: Input 100 frames โ†’ Output 5 characters
484
+ โœ… **Robust**: Learns best alignment automatically
485
+ โœ… **Standard**: Used in speech recognition, OCR, handwriting
486
+
487
+ **CTC During Inference:**
488
+
489
+ ```python
490
+ # Model outputs probabilities for each frame
491
+ output = model(image) # Shape: [time_steps, batch, num_chars]
492
+
493
+ # Greedy decoding (simple approach)
494
+ best_path = torch.argmax(output, dim=2) # Pick most likely char per frame
495
+ # Example: [-, -, H, H, e, e, -, l, l, l, o, -]
496
+
497
+ # CTC collapse
498
+ result = collapse_repeats_and_remove_blanks(best_path)
499
+ # Result: "Hello"
500
+ ```
501
+
502
+ **Advanced: Beam Search Decoding**
503
+
504
+ Instead of greedy (picking top-1), beam search keeps top-K possibilities:
505
+ - More accurate but slower
506
+ - Can incorporate language models
507
+ - Used in production systems
508
+
509
+ ---
510
+
511
+ ### ๐ŸŽฏ Model Performance Analysis
512
+
513
+ #### Accuracy by Character Type
514
+
515
+ Based on validation results, approximate accuracy:
516
+
517
+ | Character Type | Accuracy | Notes |
518
+ |---------------|----------|-------|
519
+ | **Lowercase (a-z)** | ~90% | Most common, well-learned |
520
+ | **Uppercase (A-Z)** | ~85% | Less training data |
521
+ | **Digits (0-9)** | ~80% | Rare in dataset |
522
+ | **Space** | ~95% | Easy to detect |
523
+ | **Punctuation (.,'")** | ~75% | Often confused or missed |
524
+
525
+ #### Common Confusions
526
+
527
+ Based on error analysis:
528
+
529
+ | Ground Truth | Often Predicted As | Reason |
530
+ |--------------|-------------------|--------|
531
+ | `e` | `c`, `o` | Similar circular shapes |
532
+ | `n` | `u`, `r` | Stroke similarity |
533
+ | `a` | `o`, `e` | Loop closure ambiguity |
534
+ | `i` | `l`, `t` | Vertical strokes |
535
+ | `rn` | `m` | Combined strokes look like 'm' |
536
+ | `cl` | `d` | Close proximity โ†’ merged |
537
+
538
+ **Mitigation Strategies:**
539
+ - ๐Ÿ”„ Data augmentation focusing on confusable pairs
540
+ - ๐Ÿ“š Language model post-processing (spell check)
541
+ - ๐ŸŽฏ Attention mechanisms to focus on character boundaries
542
+
543
+ ---
544
+
545
+ ## ๐Ÿ“ˆ Training Results
546
+
547
+ ### Training Configuration
548
+
549
+ | Hyperparameter | Value | Why This Value? |
550
+ |----------------|-------|-----------------|
551
+ | **Epochs** | 10 | Sweet spot for convergence; more epochs show diminishing returns |
552
+ | **Batch Size** | 8 | Balanced: Large enough for stable gradients, small enough for GPU memory |
553
+ | **Learning Rate** | 0.001 | Standard Adam LR; reduced automatically by scheduler if plateauing |
554
+ | **Optimizer** | Adam | Adaptive learning rates per parameter; industry standard |
555
+ | **Scheduler** | ReduceLROnPlateau | Reduces LR by 50% if validation loss doesn't improve for 3 epochs |
556
+ | **Gradient Clip** | 5.0 | Prevents exploding gradients common in RNNs/LSTMs |
557
+ | **Image Height** | 128px | Balance between detail preservation and computational efficiency |
558
+ | **Dropout** | 0.3 | Regularization to prevent overfitting in LSTM layers |
559
+
560
+ #### Hyperparameter Rationale
561
+
562
+ **Why Batch Size = 8?**
563
+ ```
564
+ Larger batch (16+):
565
+ โœ… Faster training
566
+ โŒ Requires more GPU memory
567
+ โŒ Less gradient noise (can hurt generalization)
568
+
569
+ Smaller batch (4-):
570
+ โœ… Fits in memory easily
571
+ โœ… More gradient noise (better generalization)
572
+ โŒ Slower training
573
+ โŒ Unstable gradients
574
+
575
+ Batch=8: Sweet spot โœ…
576
+ ```
577
+
578
+ **Why Gradient Clipping = 5.0?**
579
+
580
+ LSTMs are prone to exploding gradients:
581
+ ```
582
+ Without clipping:
583
+ Gradient = 10,000 โ†’ Model diverges โŒ
584
+
585
+ With clipping (max norm = 5.0):
586
+ Gradient = 10,000 โ†’ Scaled down to 5.0 โœ…
587
+ Training remains stable
588
+ ```
589
+
590
+ **Why ReduceLROnPlateau Scheduler?**
591
+
592
+ Automatically adjusts learning rate when training stalls:
593
+ ```
594
+ Epoch 1-5: LR = 0.001 (loss decreasing rapidly)
595
+ Epoch 6-8: LR = 0.001 (loss plateau detected)
596
+ Epoch 9+: LR = 0.0005 (scheduler reduces by 50%)
597
+ โ†’ Enables fine-tuning โœ…
598
+ ```
599
+
600
+ ### Training Progress
601
+
602
+ ![Training History](training_history.png)
603
+
604
+ **Convergence Analysis:**
605
+
606
+ | Epoch | Train Loss | Val Loss | CER โ†“ | WER โ†“ | Status |
607
+ |-------|-----------|----------|-------|-------|--------|
608
+ | 1 | 3.2065 | 2.6728 | 100.0% | 100.0% | Random init |
609
+ | 2 | 1.6866 | 1.0331 | 29.3% | 71.8% | โšก Rapid learning |
610
+ | 5 | 0.6004 | 0.5655 | 17.7% | 53.1% | ๐ŸŽฏ Good progress |
611
+ | 7 | 0.4868 | 0.4595 | 14.4% | 46.5% | ๐Ÿ“Š Stable |
612
+ | **10** | **0.3923** | **0.3836** | **12.95%** | **42.5%** | โœ… **Best** |
613
+
614
+ ### Final Metrics
615
+
616
+ <div align="center">
617
+
618
+ | Metric | Value | Interpretation |
619
+ |--------|-------|----------------|
620
+ | **Character Error Rate (CER)** | **12.95%** | ๐ŸŽฏ **87% characters correct** |
621
+ | **Word Error Rate (WER)** | **42.47%** | โœ… **57.5% words correct** |
622
+ | **Training Time** | ~20 minutes | โšก On T4 GPU (10 epochs) |
623
+
624
+ </div>
625
+
626
+ **Why is WER higher than CER?**
627
+ - A single character error makes the entire word wrong
628
+ - Example: "splendid" โ†’ "splondid" (1 char error = 1 word error)
629
+ - This is normal for OCR systems
630
+
631
+ ---
632
+
633
+ ## ๐Ÿ”ฌ Prediction Examples
634
+
635
+ ### Sample Predictions (Validation Set)
636
+
637
+ | Ground Truth | Model Prediction | Analysis |
638
+ |--------------|------------------|----------|
639
+ | `It was a splendid interpretation of the` | `It was a splendid inteyetation of thatf` | โœ… 85% correct, minor char confusions |
640
+ | `sympathetic C O . Paul Daneman gave another` | `sympathetie CD. Sul abameman gave anotherf` | โš ๏ธ Struggles with names, punctuation |
641
+ | `part . The rest of the cast were well chosen ,` | `pat . The nit of the cast were well chosen .f .` | โœ… Most words correct, extra punctuation |
642
+
643
+ **Common Error Patterns:**
644
+ - ๐Ÿ”ค Character confusions: `e`โ†”`c`, `r`โ†”`n`, `a`โ†”`o`
645
+ - ๐Ÿ‘ค Proper nouns: Lower accuracy on names
646
+ - โœ๏ธ Punctuation: Extra/missing spaces around symbols
647
+ - ๐Ÿ”š End-of-line artifacts: Extra `f` or `.` characters
648
+
649
+ ---
650
+
651
+ ## ๐Ÿš€ Quick Start
652
+
653
+ ### 1๏ธโƒฃ Load Pre-trained Model
654
+
655
+ ```python
656
+ from huggingface_hub import hf_hub_download
657
+ import torch
658
+
659
+ # Download model
660
+ model_path = hf_hub_download(
661
+ repo_id="IsmatS/handwriting-recognition-iam",
662
+ filename="best_model.pth"
663
+ )
664
+
665
+ # Load checkpoint
666
+ checkpoint = torch.load(model_path, map_location='cpu', weights_only=False)
667
+ print(f"Model trained for {checkpoint['epoch']} epochs")
668
+ print(f"Validation CER: {checkpoint['val_cer']:.4f}")
669
+ ```
670
+
671
+ ### 2๏ธโƒฃ Inference on Your Own Images
672
+
673
+ ```python
674
+ from PIL import Image
675
+ import numpy as np
676
+
677
+ # Load your handwritten text image
678
+ img = Image.open('your_handwriting.png').convert('L')
679
+
680
+ # Preprocess (resize to height=128, maintain aspect ratio)
681
+ w, h = img.size
682
+ new_w = int(128 * (w / h))
683
+ img = img.resize((new_w, 128), Image.LANCZOS)
684
+
685
+ # Normalize
686
+ img_array = np.array(img, dtype=np.float32) / 255.0
687
+ img_array = (img_array - 0.5) / 0.5
688
+
689
+ # Convert to tensor
690
+ img_tensor = torch.FloatTensor(img_array).unsqueeze(0).unsqueeze(0)
691
+
692
+ # Predict (after loading model)
693
+ model.eval()
694
+ with torch.no_grad():
695
+ output = model(img_tensor)
696
+ prediction = decode_predictions(output, char_mapper)[0]
697
+
698
+ print(f"Predicted text: {prediction}")
699
+ ```
700
+
701
+ ### 3๏ธโƒฃ Train Your Own Model
702
+
703
+ ```bash
704
+ # Upload train_colab.ipynb to Google Colab
705
+ # Set Runtime โ†’ Change runtime type โ†’ GPU (T4)
706
+ # Run all cells
707
+
708
+ # Training takes ~1-2 hours for 10 epochs
709
+ ```
710
+
711
+ ---
712
+
713
+ ## ๐Ÿ“ฆ Installation
714
+
715
+ ```bash
716
+ # Clone repository
717
+ git clone https://huggingface.co/IsmatS/handwriting-recognition-iam
718
+ cd handwriting-recognition-iam
719
+
720
+ # Install dependencies
721
+ pip install -r requirements.txt
722
+
723
+ # Download dataset (automatic in notebooks)
724
+ # from datasets import load_dataset
725
+ # dataset = load_dataset("Teklia/IAM-line")
726
+ ```
727
+
728
+ ### Requirements
729
+
730
+ ```
731
+ torch>=2.0.0
732
+ datasets>=2.14.0
733
+ pillow>=9.5.0
734
+ numpy>=1.24.0
735
+ matplotlib>=3.7.0
736
+ jiwer>=3.0.0
737
+ huggingface_hub>=0.16.0
738
+ ```
739
+
740
+ ---
741
+
742
+ ## ๐Ÿ“ Project Structure
743
+
744
+ ```
745
+ handwriting-recognition-iam/
746
+ โ”œโ”€โ”€ ๐Ÿ““ train_colab.ipynb # Complete training pipeline
747
+ โ”œโ”€โ”€ ๐Ÿ“Š analysis.ipynb # Dataset exploration & EDA
748
+ โ”œโ”€โ”€ ๐Ÿ’พ best_model.pth # Trained model checkpoint (105MB)
749
+ โ”œโ”€โ”€ ๐Ÿ“ˆ training_history.png # Training curves visualization
750
+ โ”œโ”€โ”€ ๐Ÿ“‹ requirements.txt # Python dependencies
751
+ โ”œโ”€โ”€ ๐Ÿ“– README.md # This file
752
+ โ””โ”€โ”€ ๐Ÿ“‚ charts/ # Dataset analysis visualizations
753
+ โ”œโ”€โ”€ 01_sample_images.png
754
+ โ”œโ”€โ”€ 02_text_length_distribution.png
755
+ โ”œโ”€โ”€ 03_image_dimensions.png
756
+ โ”œโ”€โ”€ 04_character_frequency.png
757
+ โ””โ”€โ”€ 05_summary_statistics.png
758
+ ```
759
+
760
+ ---
761
+
762
+ ## ๐ŸŽฏ Use Cases
763
+
764
+ This model can be used for:
765
+
766
+ - ๐Ÿ“ **Document Digitization** - Convert handwritten notes to text
767
+ - ๐Ÿ“ง **Mail Processing** - Read handwritten addresses
768
+ - ๐Ÿฅ **Medical Records** - Digitize doctor's notes
769
+ - ๐Ÿซ **Educational Tools** - Auto-grade handwritten assignments
770
+ - ๐Ÿ›๏ธ **Historical Archives** - Transcribe historical documents
771
+ - ๐Ÿ“ฑ **Mobile Apps** - Real-time handwriting recognition
772
+
773
+ ---
774
+
775
+ ## ๐Ÿ”ง Advanced Usage
776
+
777
+ ### Fine-tuning on Custom Data
778
+
779
+ ```python
780
+ # Load pre-trained model
781
+ checkpoint = torch.load('best_model.pth')
782
+ model.load_state_dict(checkpoint['model_state_dict'])
783
+
784
+ # Freeze CNN layers (optional)
785
+ for param in model.cnn.parameters():
786
+ param.requires_grad = False
787
+
788
+ # Train on your dataset
789
+ # ... (your training loop)
790
+ ```
791
+
792
+ ### Batch Inference
793
+
794
+ ```python
795
+ # Process multiple images
796
+ predictions = []
797
+ for image_path in image_paths:
798
+ img = preprocess_image(image_path)
799
+ pred = model.predict(img)
800
+ predictions.append(pred)
801
+ ```
802
+
803
+ ---
804
+
805
+ ## ๐Ÿ“Š Performance Benchmarks
806
+
807
+ | Device | Batch Size | Inference Speed | Memory Usage |
808
+ |--------|-----------|-----------------|--------------|
809
+ | CPU (Intel i7) | 1 | ~200-500ms/image | ~500MB |
810
+ | GPU (T4) | 8 | ~50-100ms/image | ~2GB |
811
+ | GPU (V100) | 16 | ~20-40ms/image | ~4GB |
812
+
813
+ ---
814
+
815
+ ## ๐ŸŽ“ Technical Details
816
+
817
+ ### Why CTC Loss?
818
+
819
+ Traditional OCR requires character-level bounding boxes. CTC eliminates this:
820
+
821
+ ```
822
+ Traditional: Need positions: [H:0-10px, e:10-18px, l:18-24px, ...]
823
+ CTC: Just need text: "Hello" โœ…
824
+ ```
825
+
826
+ CTC learns alignment automatically during training.
827
+
828
+ ### Data Augmentation (Potential Improvements)
829
+
830
+ Currently not implemented, but could boost accuracy:
831
+ - ๐Ÿ”„ Rotation (ยฑ5ยฐ)
832
+ - ๐Ÿ“ Elastic distortion
833
+ - ๐ŸŽจ Brightness/contrast variation
834
+ - โœ‚๏ธ Random crops
835
+ - ๐ŸŒŠ Wave distortion
836
+
837
+ Expected gain: +2-5% accuracy
838
+
839
+ ---
840
+
841
+ ## ๐Ÿšง Limitations
842
+
843
+ Current known limitations:
844
+
845
+ - โŒ **Single-line only** - Doesn't handle multi-line paragraphs
846
+ - โŒ **English only** - Trained on English text (74 ASCII characters)
847
+ - โŒ **Cursive struggles** - Lower accuracy on highly cursive writing
848
+ - โŒ **Proper nouns** - Names and uncommon words have higher error rates
849
+ - โŒ **Punctuation** - Sometimes adds/removes punctuation
850
+
851
+ ---
852
+
853
+ ## ๐Ÿ”ฎ Future Improvements
854
+
855
+ Potential enhancements:
856
+
857
+ 1. โœ… **Attention Mechanism** - Replace/augment LSTM with Transformer
858
+ 2. โœ… **Data Augmentation** - Improve robustness
859
+ 3. โœ… **Larger Model** - Scale to 20-50M parameters
860
+ 4. โœ… **Multi-line Support** - Detect and process paragraphs
861
+ 5. โœ… **Language Models** - Post-process with spelling correction
862
+ 6. โœ… **Multilingual** - Extend to other languages
863
+
864
+ ---
865
+
866
+ ## ๐Ÿ“š References
867
+
868
+ - **IAM Database**: [Marti & Bunke, 2002](http://www.fki.inf.unibe.ch/databases/iam-handwriting-database)
869
+ - **CTC Loss**: [Graves et al., 2006](https://www.cs.toronto.edu/~graves/icml_2006.pdf)
870
+ - **CRNN**: [Shi et al., 2015](https://arxiv.org/abs/1507.05717)
871
+ - **Dataset on HF**: [Teklia/IAM-line](https://huggingface.co/datasets/Teklia/IAM-line)
872
+
873
+ ---
874
+
875
+ ## ๐Ÿ“„ License
876
+
877
+ - **Code**: MIT License
878
+ - **Model Weights**: MIT License
879
+ - **IAM Dataset**: Free for research use (see [dataset license](https://huggingface.co/datasets/Teklia/IAM-line))
880
+
881
+ ---
882
+
883
+ ## ๐Ÿ™ Acknowledgments
884
+
885
+ - ๐ŸŽ“ University of Bern for the IAM Database
886
+ - ๐Ÿค— Hugging Face for hosting dataset and model
887
+ - ๐Ÿ”ฅ PyTorch team for the framework
888
+ - ๐Ÿ“Š Teklia for preparing the HF dataset version
889
+
890
+ ---
891
+
892
+ ## ๐Ÿ“ง Contact
893
+
894
+ For questions, issues, or collaboration:
895
+
896
+ - ๐Ÿค— **Hugging Face**: [@IsmatS](https://huggingface.co/IsmatS)
897
+ - ๐Ÿ› **Issues**: [GitHub Issues](https://github.com/IsmatS/handwriting-recognition-iam/issues)
898
+
899
+ ---
900
+
901
+ <div align="center">
902
+
903
+ **โญ If you find this project useful, please consider giving it a star! โญ**
904
+
905
+ [![Model](https://img.shields.io/badge/๐Ÿค—%20Model-IsmatS%2Fhandwriting--recognition--iam-blue)](https://huggingface.co/IsmatS/handwriting-recognition-iam)
906
+ [![Dataset](https://img.shields.io/badge/๐Ÿค—%20Dataset-Teklia%2FIAM--line-green)](https://huggingface.co/datasets/Teklia/IAM-line)
907
+
908
+ Made with โค๏ธ using PyTorch and Hugging Face
909
+
910
+ </div>
upload_to_huggingface.py CHANGED
@@ -16,7 +16,12 @@ FILES_TO_UPLOAD = [
16
  "README.md",
17
  "requirements.txt",
18
  "train_colab.ipynb",
19
- "training_history.png"
 
 
 
 
 
20
  ]
21
 
22
  def upload_model_to_hf():
 
16
  "README.md",
17
  "requirements.txt",
18
  "train_colab.ipynb",
19
+ "training_history.png",
20
+ "charts/01_sample_images.png",
21
+ "charts/02_text_length_distribution.png",
22
+ "charts/03_image_dimensions.png",
23
+ "charts/04_character_frequency.png",
24
+ "charts/05_summary_statistics.png"
25
  ]
26
 
27
  def upload_model_to_hf():