How to Extract Emails from PDFs and Images Using PHP

Introduction

In our previous blogs, we focused on building a basic email extractor using PHP and MySQL and discussed advanced techniques to enhance its functionality. In this blog, we will explore how to extract email addresses from different content types, specifically PDFs and images. This will provide you with a comprehensive understanding of how to broaden your email extraction capabilities beyond just web pages.

1. Understanding the Challenges

Before diving into the extraction process, it’s essential to understand the challenges associated with different content types:

• PDF Files: PDFs can contain text in various formats, including images, tables, and other complex layouts, making extraction tricky.
• Images: Email addresses in images require Optical Character Recognition (OCR) technology to convert the visual text into machine-readable format.

2. Extracting Emails from PDF Files

To extract email addresses from PDFs, you can use libraries like TCPDF or FPDF for PHP. However, a more straightforward approach is to use the pdfparser library or pdftotext command-line utility.

Using pdftotext Command-Line Utility

Installation: Ensure you have pdftotext installed on your server. For most Linux distributions, you can install it using:

sudo apt-get install poppler-utils

Extracting Text from PDF: Use the following PHP code to extract text from a PDF file:

function extractEmailsFromPDF($filePath) {
    $text = shell_exec("pdftotext " . escapeshellarg($filePath) . " -");
    return extractEmailsFromText($text);
}

function extractEmailsFromText($text) {
    preg_match_all('/[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,4}/i', $text, $matches);
    return array_unique($matches[0]);
}

Storing Extracted Emails: Once you have extracted the emails, you can store them in your MySQL database using the techniques discussed in previous blogs.

3. Extracting Emails from Images

Extracting email addresses from images involves using OCR technology. One of the popular libraries for this purpose is Tesseract OCR.

Using Tesseract OCR

Installation: Install Tesseract OCR on your server:

For Linux:

sudo apt-get install tesseract-ocr

For Windows, download the installer from Tesseract at UB Mannheim.

Extracting Text from Images: Use the following PHP code to process images and extract text:

function extractEmailsFromImage($imagePath) {
    // Run Tesseract command to extract text
    $text = shell_exec("tesseract " . escapeshellarg($imagePath) . " stdout");
    return extractEmailsFromText($text);
}

Integration into Your Project: Similar to PDF extraction, you can now integrate this functionality into your email extractor. Combine it with your existing email extraction logic to handle various input formats.

4. Combining Multiple Extraction Methods

To create a robust email extractor that can handle PDFs, images, and web pages, consider the following:

• File Upload Handling: Allow users to upload multiple file types (PDFs, images) in addition to providing URLs. Use an HTML form to facilitate this.
• Dynamic Extraction Logic: Implement logic to determine the file type and call the appropriate extraction function based on the content type.

if (isset($_FILES['file'])) {
    $fileType = $_FILES['file']['type'];
    $filePath = $_FILES['file']['tmp_name'];

    if ($fileType === 'application/pdf') {
        $emails = extractEmailsFromPDF($filePath);
    } elseif (strpos($fileType, 'image/') === 0) {
        $emails = extractEmailsFromImage($filePath);
    }
    // Handle URLs as well...
}

5. Data Quality and Cleanup

Once you extract emails from different sources, it’s essential to clean up the data. Here are some steps to consider:

• Remove Duplicates: Implement checks to prevent duplicate entries across all extracted emails.
• Sanitize Emails: Ensure that the extracted emails conform to the correct format before storing them in the database.
• Log Extraction Results: Maintain a log of successful and failed extractions for better troubleshooting.

Conclusion

In this blog, we explored advanced methods for extracting emails from PDFs and images, broadening the scope of your email extraction capabilities. By integrating these techniques into your existing email extractor, you can create a versatile tool that efficiently gathers email addresses from various content types.

In the next blog, we will discuss how to implement data scraping ethically and comply with legal guidelines. Stay tuned!