Build Your Own OCR Engine for Wingdings

Optical Character Recognition (OCR) has revolutionized the way in which we work together with textual knowledge in actual life, enabling machines to learn and interpret textual content from photos, scanned paperwork, and handwritten notes. From digitizing books and automating knowledge entry to real-time textual content translation in augmented actuality, OCR purposes are extremely various and impactful. A few of its software might embrace:

• Doc Digitization: Converts bodily paperwork into editable and searchable digital codecs.
• Bill Scanning: Extracts particulars like quantities, dates, and vendor names for automated processing.
• Knowledge Entry Automation: Accelerates workflows by extracting textual content from varieties and receipts.
• Actual-Time Translation: Interprets international textual content from photos or video streams in augmented actuality.
• License Plate Recognition: Identifies automobiles in visitors techniques and parking administration.
• Accessibility Instruments: Converts textual content to speech for visually impaired people.
• Archiving and Preservation: Digitizes historic paperwork for storage and analysis.

On this publish, we take OCR a step additional by constructing a customized OCR mannequin for recognizing textual content within the Wingdings font—a symbolic font with distinctive characters usually utilized in inventive and technical contexts. Whereas conventional OCR fashions are educated for normal textual content, this tradition mannequin bridges the hole for area of interest purposes, unlocking potentialities for translating symbolic textual content into readable English, whether or not for accessibility, design, or archival functions. By means of this, we display the facility of OCR to adapt and cater to specialised use instances within the fashionable world.

For builders and managers trying to streamline doc workflows akin to OCR extraction and past, instruments just like the Nanonets PDF AI supply priceless integration choices. Coupled with cutting-edge LLM capabilities, these can considerably improve your workflows, guaranteeing environment friendly knowledge dealing with. Moreover, instruments like Nanonets’ PDF Summarizer can additional automate processes by summarizing prolonged paperwork.

Is There a Want for Customized OCR within the Age of Imaginative and prescient-Language Fashions?

Imaginative and prescient-language fashions, akin to Flamingo, Qwen2-VL, have revolutionized how machines perceive photos and textual content by bridging the hole between the 2 modalities. They will course of and cause about photos and related textual content in a extra generalized method.

Regardless of their spectacular capabilities, there stays a necessity for customized OCR techniques in particular situations, primarily on account of:

• Accuracy for Particular Languages or Scripts: Many vision-language fashions deal with widely-used languages. Customized OCR can handle low-resource or regional languages, together with Indic scripts, calligraphy, or underrepresented dialects.
• Light-weight and Useful resource-Constrained Environments: Customized OCR fashions could be optimized for edge gadgets with restricted computational energy, akin to embedded techniques or cell purposes. Imaginative and prescient-language fashions, in distinction, are sometimes too resource-intensive for such use instances. For real-time or high-volume purposes, akin to bill processing or automated doc evaluation, customized OCR options could be tailor-made for velocity and accuracy.
• Knowledge Privateness and Safety: Sure industries, akin to healthcare or finance, require OCR options that function offline or inside personal infrastructures to fulfill strict knowledge privateness laws. Customized OCR ensures compliance, whereas cloud-based vision-language fashions would possibly introduce safety issues.
• Price-Effectiveness: Deploying and fine-tuning huge vision-language fashions could be cost-prohibitive for small-scale companies or particular initiatives. Customized OCR could be a extra inexpensive and targeted various.

Construct a Customized OCR Mannequin for Wingdings

To discover the potential of customized OCR techniques, we are going to construct an OCR engine particularly for the Wingdings font.

Beneath are the steps and parts we are going to observe:

• Generate a customized dataset of Wingdings font photos paired with their corresponding labels in English phrases.
• Create a customized OCR mannequin able to recognizing symbols within the Wingdings font. We are going to use the Imaginative and prescient Transformer for Scene Textual content Recognition (ViTSTR), a state-of-the-art structure designed for image-captioning duties. Not like conventional CNN-based fashions, ViTSTR leverages the transformer structure, which excels at capturing long-range dependencies in photos, making it perfect for recognizing complicated textual content constructions, together with the intricate patterns of Wingdings fonts.
• Practice the mannequin on the customized dataset of Wingdings symbols.
• Take a look at the mannequin on unseen knowledge to guage its accuracy.

For this challenge, we are going to make the most of Google Colab for coaching, leveraging its 16 GB T4 GPU for quicker computation.

Making a Wingdings Dataset

What’s Wingdings?

Wingdings is a symbolic font developed by Microsoft that consists of a set of icons, shapes, and pictograms as a substitute of conventional alphanumeric characters. Launched in 1990, Wingdings maps keyboard inputs to graphical symbols, akin to arrows, smiley faces, checkmarks, and different ornamental icons. It’s usually used for design functions, visible communication, or as a playful font in digital content material.

Because of its symbolic nature, deciphering Wingdings textual content programmatically poses a problem, making it an fascinating use case for customized OCR techniques.

Dataset Creation

Since no present dataset is on the market for Optical Character Recognition (OCR) in Wingdings font, we created one from scratch. The method entails producing photos of phrases within the Wingdings font and mapping them to their corresponding English phrases.

To attain this, we used the Wingdings Translator to transform English phrases into their Wingdings representations. For every transformed phrase, a picture was manually generated and saved in a folder named “wingdings_word_images”.

Moreover, we create a “metadata.csv” file to take care of a structured document of the dataset together with the picture path. This file comprises two columns:

1. Picture Path: Specifies the file path for every picture within the dataset.
2. English Phrase: Lists the corresponding English phrase for every Wingdings illustration.

The dataset could be downloaded from this link.

Preprocessing the Dataset

The pictures within the dataset fluctuate in measurement as a result of handbook creation course of. To make sure uniformity and compatibility with OCR fashions, we preprocess the pictures by resizing and padding them.

import pandas as pd
import numpy as np
from PIL import Picture
import os
from tqdm import tqdm

def pad_image(picture, target_size=(224, 224)):
    """Pad picture to focus on measurement whereas sustaining side ratio"""
    if picture.mode != 'RGB':
        picture = picture.convert('RGB')
    
    # Get present measurement
    width, top = picture.measurement
    
    # Calculate padding
    aspect_ratio = width / top
    if aspect_ratio > 1:
        # Width is bigger
        new_width = target_size[0]
        new_height = int(new_width / aspect_ratio)
    else:
        # Top is bigger
        new_height = target_size[1]
        new_width = int(new_height * aspect_ratio)
    
    # Resize picture sustaining side ratio
    picture = picture.resize((new_width, new_height), Picture.Resampling.LANCZOS)
    
    # Create new picture with padding
    new_image = Picture.new('RGB', target_size, (255, 255, 255))
    
    # Paste resized picture in middle
    paste_x = (target_size[0] - new_width) // 2
    paste_y = (target_size[1] - new_height) // 2
    new_image.paste(picture, (paste_x, paste_y))
    
    return new_image

# Learn the metadata
df = pd.read_csv('metadata.csv')

# Create output listing for processed photos
processed_dir="processed_images"
os.makedirs(processed_dir, exist_ok=True)

# Course of every picture
new_paths = []
for idx, row in tqdm(df.iterrows(), whole=len(df), desc="Processing photos"):
    # Load picture
    img_path = row['image_path']
    img = Picture.open(img_path)
    
    # Pad picture
    processed_img = pad_image(img)
    
    # Save processed picture
    new_path = os.path.be a part of(processed_dir, f'processed_{os.path.basename(img_path)}')
    processed_img.save(new_path)
    new_paths.append(new_path)

# Replace dataframe with new paths
df['processed_image_path'] = new_paths
df.to_csv('processed_metadata.csv', index=False)

print("Picture preprocessing accomplished!")
print(f"Whole photos processed: {len(df)}")

First, every picture is resized to a hard and fast top whereas sustaining its side ratio to protect the visible construction of the Wingdings characters. Subsequent, we apply padding to make all photos the identical dimensions, usually a sq. form, to suit the enter necessities of neural networks. The padding is added symmetrically across the resized picture, with the background colour matching the unique picture’s background.

Splitting the Dataset

The dataset is split into three subsets: coaching (70%), validation (dev) (15%), and testing (15%). The coaching set is used to show the mannequin, the validation set helps fine-tune hyperparameters and monitor overfitting, and the take a look at set evaluates the mannequin’s efficiency on unseen knowledge. This random break up ensures every subset is various and consultant, selling efficient generalization.

import pandas as pd
from sklearn.model_selection import train_test_split

# Learn the processed metadata
df = pd.read_csv('processed_metadata.csv')

# First break up: practice and non permanent
train_df, temp_df = train_test_split(df, train_size=0.7, random_state=42)

# Second break up: validation and take a look at from non permanent
val_df, test_df = train_test_split(temp_df, train_size=0.5, random_state=42)

# Save splits to CSV
train_df.to_csv('practice.csv', index=False)
val_df.to_csv('val.csv', index=False)
test_df.to_csv('take a look at.csv', index=False)

print("Knowledge break up statistics:")
print(f"Coaching samples: {len(train_df)}")
print(f"Validation samples: {len(val_df)}")
print(f"Take a look at samples: {len(test_df)}")

Visualizing the Dataset

To higher perceive the dataset, we visualize samples from every break up. Particularly, we show 5 examples from the coaching set, 5 from the validation set, and 5 from the take a look at set. Every visualization consists of the Wingdings textual content as a picture alongside its corresponding label in English. This step supplies a transparent overview of the information distribution throughout the splits and ensures the correctness of the dataset mappings.

import matplotlib.pyplot as plt
from PIL import Picture
import pandas as pd

def plot_samples(df, num_samples=5, title="Pattern Photos"):
    # Set bigger font sizes
    plt.rcParams.replace({
        'font.measurement': 14,          # Base font measurement
        'axes.titlesize': 16,     # Subplot title font measurement
        'determine.titlesize': 20    # Principal title font measurement
    })
    
    fig, axes = plt.subplots(1, num_samples, figsize=(20, 4))
    fig.suptitle(title, fontsize=20, y=1.05)
    
    # Randomly pattern photos
    sample_df = df.pattern(n=num_samples)
    
    for idx, (_, row) in enumerate(sample_df.iterrows()):
        img = Picture.open(row['processed_image_path'])
        axes[idx].imshow(img)
        axes[idx].set_title(f"Label: {row['english_word_label']}", fontsize=16, pad=10)
        axes[idx].axis('off')
    
    plt.tight_layout()
    plt.present()

# Load splits
train_df = pd.read_csv('practice.csv')
val_df = pd.read_csv('val.csv')
test_df = pd.read_csv('take a look at.csv')

# Plot samples from every break up
plot_samples(train_df, title="Coaching Samples")
plot_samples(val_df, title="Validation Samples")
plot_samples(test_df, title="Take a look at Samples")

Samples from the information are visualised as:

Practice an OCR Mannequin

First we have to import the required libraries and dependencies:

import torch
import torch.nn as nn
from torch.utils.knowledge import Dataset, DataLoader
from transformers import VisionEncoderDecoderModel, ViTImageProcessor, AutoTokenizer
from PIL import Picture
import pandas as pd
from tqdm import tqdm

Mannequin Coaching with ViTSTR

We use a Imaginative and prescient Encoder-Decoder mannequin, particularly ViTSTR (Imaginative and prescient Transformer for Scene Textual content Recognition). We fine-tune it for our Wingdings OCR process. The encoder processes the Wingdings textual content photos utilizing a ViT (Imaginative and prescient Transformer) spine, whereas the decoder generates the corresponding English phrase labels.

Throughout coaching, the mannequin learns to map pixel-level data from the pictures to significant English textual content. The coaching and validation losses are monitored to evaluate mannequin efficiency, guaranteeing it generalizes effectively. After coaching, the fine-tuned mannequin is saved for inference on unseen Wingdings textual content photos. We use pre-trained parts from Hugging Face for our OCR pipeline and positive tune them. The ViTImageProcessor prepares photos for the Imaginative and prescient Transformer (ViT) encoder, whereas the bert-base-uncased tokenizer processes English textual content labels for the decoder. The VisionEncoderDecoderModel, combining a ViT encoder and GPT-2 decoder, is fine-tuned for picture captioning duties, making it perfect for studying the Wingdings-to-English mapping.

class WingdingsDataset(Dataset):
    def __init__(self, csv_path, processor, tokenizer):
        self.df = pd.read_csv(csv_path)
        self.processor = processor
        self.tokenizer = tokenizer
    
    def __len__(self):
        return len(self.df)
    
    def __getitem__(self, idx):
        row = self.df.iloc[idx]
        picture = Picture.open(row['processed_image_path'])
        label = row['english_word_label']
        
        # Course of picture
        pixel_values = self.processor(picture, return_tensors="pt").pixel_values
        
        # Course of label
        encoding = self.tokenizer(
            label,
            padding="max_length",
            max_length=16,
            truncation=True,
            return_tensors="pt"
        )
        
        return {
            'pixel_values': pixel_values.squeeze(),
            'labels': encoding.input_ids.squeeze(),
            'textual content': label
        }

def train_epoch(mannequin, dataloader, optimizer, machine):
    mannequin.practice()
    total_loss = 0
    progress_bar = tqdm(dataloader, desc="Coaching")
    
    for batch in progress_bar:
        pixel_values = batch['pixel_values'].to(machine)
        labels = batch['labels'].to(machine)
        
        outputs = mannequin(pixel_values=pixel_values, labels=labels)
        loss = outputs.loss
        
        optimizer.zero_grad()
        loss.backward()
        optimizer.step()
        
        total_loss += loss.merchandise()
        progress_bar.set_postfix({'loss': loss.merchandise()})
    
    return total_loss / len(dataloader)

def validate(mannequin, dataloader, machine):
    mannequin.eval()
    total_loss = 0
    
    with torch.no_grad():
        for batch in tqdm(dataloader, desc="Validating"):
            pixel_values = batch['pixel_values'].to(machine)
            labels = batch['labels'].to(machine)
            
            outputs = mannequin(pixel_values=pixel_values, labels=labels)
            loss = outputs.loss
            total_loss += loss.merchandise()
    
    return total_loss / len(dataloader)

# Initialize fashions and tokenizers
processor = ViTImageProcessor.from_pretrained("google/vit-base-patch16-224-in21k")
tokenizer = AutoTokenizer.from_pretrained("bert-base-uncased")
mannequin = VisionEncoderDecoderModel.from_pretrained("nlpconnect/vit-gpt2-image-captioning")

# Create datasets
train_dataset = WingdingsDataset('practice.csv', processor, tokenizer)
val_dataset = WingdingsDataset('val.csv', processor, tokenizer)

# Create dataloaders
train_loader = DataLoader(train_dataset, batch_size=32, shuffle=True)
val_loader = DataLoader(val_dataset, batch_size=32)

# Setup coaching
machine = torch.machine('cuda' if torch.cuda.is_available() else 'cpu')
mannequin = mannequin.to(machine)
optimizer = torch.optim.AdamW(mannequin.parameters(), lr=5e-5)
num_epochs = 20 #(change in keeping with want)

# Coaching loop
for epoch in vary(num_epochs):
    print(f"nEpoch {epoch+1}/{num_epochs}")
    
    train_loss = train_epoch(mannequin, train_loader, optimizer, machine)
    val_loss = validate(mannequin, val_loader, machine)
    
    print(f"Coaching Loss: {train_loss:.4f}")
    print(f"Validation Loss: {val_loss:.4f}")

# Save the mannequin
mannequin.save_pretrained('wingdings_ocr_model')
print("nTraining accomplished and mannequin saved!")

The coaching is carried for 20 epochs in Google Colab. Though it offers truthful end result with 20 epochs, it is a hyper parameter and could be elevated to achieve higher accuracy. Dropout, Picture Augmentation and Batch Normalization are a number of extra hyper-parameters one can play with to make sure mannequin will not be overfitting. The coaching stats and the loss and accuracy curve for practice and validation units on first and final epochs are given under:

Epoch 1/20
Coaching: 100%|██████████| 22/22 [00:36<00:00,  1.64s/it, loss=1.13]
Validating: 100%|██████████| 5/5 [00:02<00:00,  1.71it/s]
Coaching Loss: 2.2776
Validation Loss: 1.0183

..........
..........
..........
..........

Epoch 20/20
Coaching: 100%|██████████| 22/22 [00:35<00:00,  1.61s/it, loss=0.0316]
Validating: 100%|██████████| 5/5 [00:02<00:00,  1.73it/s]
Coaching Loss: 0.0246
Validation Loss: 0.5970

Coaching accomplished and mannequin saved!

Utilizing the Saved Mannequin

As soon as the mannequin has been educated and saved, you may simply load it for inference on new Wingdings photos. The take a look at.csv file created throughout preprocessing is used to create the test_dataset. Right here’s the code to load the saved mannequin and make predictions:

# Load the educated mannequin
mannequin = VisionEncoderDecoderModel.from_pretrained('wingdings_ocr_model')
processor = ViTImageProcessor.from_pretrained("google/vit-base-patch16-224-in21k")
tokenizer = AutoTokenizer.from_pretrained("bert-base-uncased")

# Create take a look at dataset and dataloader
test_dataset = WingdingsDataset('take a look at.csv', processor, tokenizer)
test_loader = DataLoader(test_dataset, batch_size=32)

Mannequin Analysis

After coaching, we consider the mannequin’s efficiency on the take a look at break up to measure its efficiency. To realize insights into the mannequin’s efficiency, we randomly choose 10 samples from the take a look at break up. For every pattern, we show the true label (English phrase) alongside the mannequin’s prediction and verify in the event that they match.

import seaborn as sns
import matplotlib.pyplot as plt
from PIL import Picture

def plot_prediction_samples(image_paths, true_labels, pred_labels, num_samples=10):
    # Set determine measurement and font sizes
    plt.rcParams.replace({
        'font.measurement': 14,
        'axes.titlesize': 18,
        'determine.titlesize': 22
    })
    
    # Calculate grid dimensions
    num_rows = 2
    num_cols = 5
    num_samples = min(num_samples, len(image_paths))
    
    # Create determine
    fig, axes = plt.subplots(num_rows, num_cols, figsize=(20, 8))
    fig.suptitle('Pattern Predictions from Take a look at Set', fontsize=22, y=1.05)
    
    # Flatten axes for simpler indexing
    axes_flat = axes.flatten()
    
    for i in vary(num_samples):
        ax = axes_flat[i]
        
        # Load and show picture
        img = Picture.open(image_paths[i])
        ax.imshow(img)
        
        # Create label textual content
        true_text = f"True: {true_labels[i]}"
        pred_text = f"Pred: {pred_labels[i]}"
        
        # Set colour primarily based on correctness
        colour="inexperienced" if true_labels[i] == pred_labels[i] else 'pink'
        
        # Add textual content above picture
        ax.set_title(f"{true_text}n{pred_text}", 
                    fontsize=14,
                    colour=colour,
                    pad=10,
                    bbox=dict(facecolor="white", 
                             alpha=0.8,
                             edgecolor="none",
                             pad=3))
        
        # Take away axes
        ax.axis('off')
    
    # Take away any empty subplots
    for i in vary(num_samples, num_rows * num_cols):
        fig.delaxes(axes_flat[i])
    
    plt.tight_layout()
    plt.present()
    
# Analysis
machine = torch.machine('cuda' if torch.cuda.is_available() else 'cpu')
mannequin = mannequin.to(machine)
mannequin.eval()

predictions = []
ground_truth = []
image_paths = []

with torch.no_grad():
    for batch in tqdm(test_loader, desc="Evaluating"):
        pixel_values = batch['pixel_values'].to(machine)
        texts = batch['text']
        
        outputs = mannequin.generate(pixel_values)
        pred_texts = tokenizer.batch_decode(outputs, skip_special_tokens=True)
        
        predictions.prolong(pred_texts)
        ground_truth.prolong(texts)
        image_paths.prolong([row['processed_image_path'] for _, row in test_dataset.df.iterrows()])

# Calculate and print accuracy
accuracy = accuracy_score(ground_truth, predictions)
print(f"nTest Accuracy: {accuracy:.4f}")

# Show pattern predictions in grid
print("nDisplaying pattern predictions:")
plot_prediction_samples(image_paths, ground_truth, predictions)    

The analysis offers the next output:

Analysing the output given by the mannequin, we discover that the predictions match the reference/authentic labels pretty effectively. Though the final prediction is right it’s displayed in pink due to the areas within the generated textual content.

All of the code and dataset used above could be discovered on this Github repository. And the tip to finish coaching could be discovered within the following colab pocket book

Dialogue

After we see the outputs, it turns into clear that the mannequin performs very well. The anticipated labels are correct, and the visible comparability with the true labels demonstrates the mannequin’s sturdy functionality in recognizing the right lessons.

The mannequin’s wonderful efficiency could possibly be attributed to the strong structure of the Imaginative and prescient Transformer for Scene Textual content Recognition (ViTSTR). ViTSTR stands out on account of its means to seamlessly mix the facility of Imaginative and prescient Transformers (ViT) with language fashions for textual content recognition duties.

A comparability could possibly be made by experimenting with completely different ViT structure sizes, akin to various the variety of layers, embedding dimensions, or the variety of consideration heads. Fashions like ViT-Base, ViT-Giant, and ViT-Enormous could be examined, together with various architectures like:

• DeiT (Knowledge-efficient Picture Transformer)
• Swin Transformer

By evaluating these fashions of various scales, we will establish which structure is essentially the most environment friendly when it comes to efficiency and computational assets. This may assist decide the optimum mannequin measurement that balances accuracy and effectivity for the given process.

For duties like extracting data from paperwork, instruments akin to Nanonets’ Chat with PDF have evaluated and used a number of state of the LLMs together with customized in-house educated fashions and may supply a dependable technique to work together with content material, guaranteeing correct knowledge extraction with out danger of misrepresentation.