Image Text Finder
How to Search and Compare Text in Images with Aspose.OCR

How to Search and Compare Text in Images with Aspose.OCR

Searching or comparing text inside images is essential for compliance, digital archives, and automated classification. Aspose.OCR Image Text Finder for .NET lets you identify, search, and compare image text with accuracy—across a range of use cases from PII detection to legal review.

Real-World Problem

Businesses often need to search for sensitive content, verify signatures, or compare text between different versions of image files. Manual checks are slow and unreliable, especially for large digital archives or document sets.

Solution Overview

With Aspose.OCR, you can search for specific text or patterns (using strings or regex) within images, and compare the textual content of two images to spot differences. Great for contract review, compliance, or digital asset management.

Prerequisites

You’ll need:

  1. Visual Studio 2019 or later
  2. .NET 6.0 or later (or .NET Framework 4.6.2+)
  3. Aspose.OCR for .NET from NuGet
  4. Basic C# skills
PM> Install-Package Aspose.OCR

Step-by-Step Implementation

Step 1: Install and Configure Aspose.OCR

Add the package and required namespaces:

using Aspose.OCR;

Step 2: Prepare Your Image Files

Set up the images you want to search or compare.

string img1 = "document1.png";
string img2 = "document2.jpg";

Step 3: Configure Search and Comparison Options

Configure settings for text searching (string or regex) and comparison.

RecognitionSettings settings = new RecognitionSettings();
settings.Language = Language.English; // Adjust as needed

Step 4: Search for Text in an Image

Use the ImageHasText method for fast, flexible text search (supports strings and regex):

AsposeOcr ocr = new AsposeOcr();
bool isFound = ocr.ImageHasText(img1, "Confidential", settings); // String search
Console.WriteLine($"Text found: {isFound}");

// Regex search example:
bool regexFound = ocr.ImageHasText(img1, @"\d{3}-\d{2}-\d{4}", settings); // e.g., US SSN pattern
Console.WriteLine($"Regex found: {regexFound}");

Step 5: Compare Text of Two Images

Use CompareImageTexts to spot differences in textual content:

int similarity = ocr.CompareImageTexts(img1, img2, settings, true); // true = case-insensitive
Console.WriteLine($"Image text similarity: {similarity}%");

Step 6: Add Error Handling

Catch and handle errors for production robustness:

try
{
    AsposeOcr ocr = new AsposeOcr();
    bool found = ocr.ImageHasText(img1, "PII", settings);
    int sim = ocr.CompareImageTexts(img1, img2, settings, false);
}
catch (Exception ex)
{
    Console.WriteLine($"Error: {ex.Message}");
}

Step 7: Optimize for Bulk Search or Comparison

  • Process images in batches using async or parallel patterns
  • Preprocess images (crop, clean up) for higher accuracy
  • Fine-tune regex for advanced scenarios
// Example: Search for a pattern in all images in a folder
foreach (string file in Directory.GetFiles("./archive", "*.png"))
{
    bool found = ocr.ImageHasText(file, "Confidential", settings);
    if (found) { Console.WriteLine($"Found in: {file}"); }
}

Step 8: Complete Example 

using Aspose.OCR;
using System;

class Program
{
    static void Main(string[] args)
    {
        try
        {
            string img1 = "contract1.png";
            string img2 = "contract2.png";

            RecognitionSettings settings = new RecognitionSettings();
            settings.Language = Language.English;

            AsposeOcr ocr = new AsposeOcr();
            // Search for specific text
            bool isFound = ocr.ImageHasText(img1, "NDA", settings);
            Console.WriteLine($"Text found: {isFound}");

            // Compare two images
            int similarity = ocr.CompareImageTexts(img1, img2, settings, true);
            Console.WriteLine($"Image text similarity: {similarity}%");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }
}

Use Cases and Applications

Compliance and PII Detection

Search for confidential data or patterns (like IDs, SSNs) inside digital image archives.

Legal and Contract Review

Compare image-based contracts or documents for textual differences after signing or editing.

Digital Asset Management

Enable automated tagging or search in large image repositories for business process automation.

Common Challenges and Solutions

Challenge 1: Images with Varied Text Styles

Solution: Use case-insensitive and regex matching; test on diverse fonts/backgrounds.

Challenge 2: Large Batch Searches

Solution: Use parallel or asynchronous workflows, and preprocess images where possible.

Challenge 3: Complex Patterns or Redacted Text

Solution: Refine regex and test across sample images; tune settings for noisy or redacted images.

Performance Considerations

  • Batch process for speed on large archives
  • Use high-quality source images for best accuracy
  • Tune search patterns to minimize false positives

Best Practices

  1. Test all search and comparison patterns on sample sets first
  2. Securely handle and log sensitive information or search results
  3. Regularly update Aspose.OCR for feature and accuracy improvements

Advanced Scenarios

Scenario 1: Advanced Regex for Redaction 

bool found = ocr.ImageHasText(img1, @"(Account|Card)\s*#:?\s*\d{4,}", settings);

Scenario 2: Multi-Language Search 

settings.Language = Language.French;
bool isFound = ocr.ImageHasText(img1, "Confidentiel", settings);

Conclusion

Aspose.OCR Image Text Finder for .NET empowers you to search, detect, and compare image-based text efficiently—across archives, legal, and compliance workflows. Bring automation to manual review tasks with robust, accurate text search.

Find more examples in the Aspose.OCR for .NET API Reference .

 English