Image Text Finder
How to Search for Multiple Keywords or Patterns in Images

How to Search for Multiple Keywords or Patterns in Images

Searching for multiple keywords or text patterns in large image archives is crucial for compliance, security, and digital discovery. Aspose.OCR Image Text Finder for .NET makes it easy to batch scan images for lists of keywords or regex patterns.

Real-World Problem

Manual review of images for multiple terms (e.g., names, IDs, confidential phrases) is slow and unreliable, especially across thousands of files.

Solution Overview

Automate detection by running multi-keyword or regex searches on batches of images. Report or act on matches for compliance, HR, or digital forensics use cases.

Prerequisites

  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
PM> Install-Package Aspose.OCR

Step-by-Step Implementation

Step 1: Install and Configure Aspose.OCR 

using Aspose.OCR;

Step 2: Define Your Keywords or Patterns 

List<string> keywords = new List<string> { "Confidential", "PII", "Invoice", "2025" };
List<string> regexPatterns = new List<string> { @"\d{3}-\d{2}-\d{4}", @"[A-Z]{2}[0-9]{6}" }; // SSN, Passport

Step 3: Batch Search Images for Keywords/Patterns 

string[] files = Directory.GetFiles("./input", "*.png");
RecognitionSettings settings = new RecognitionSettings();
settings.Language = Language.English;
AsposeOcr ocr = new AsposeOcr();
foreach (string file in files)
{
    foreach (string keyword in keywords)
    {
        bool found = ocr.ImageHasText(file, keyword, settings);
        if (found) Console.WriteLine($"Keyword '{keyword}' found in {file}");
    }
    foreach (string pattern in regexPatterns)
    {
        bool found = ocr.ImageHasText(file, pattern, settings);
        if (found) Console.WriteLine($"Pattern '{pattern}' found in {file}");
    }
}

Step 4: Log and Act on Matches

  • Save results to CSV, send alerts, or trigger workflow on match.
// Example: Append to log file
File.AppendAllText("search_log.csv", $"{file},{keyword or pattern},found\n");

Step 5: Error Handling and Performance

  • Use try/catch for robust batch jobs
  • Parallelize for large sets if needed
try
{
    // Searching logic
}
catch (Exception ex)
{
    File.AppendAllText("search_errors.log", ex.Message + Environment.NewLine);
}

Step 6: Complete Example 

using Aspose.OCR;
using System;
using System.Collections.Generic;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        List<string> keywords = new List<string> { "Confidential", "PII", "Invoice", "2025" };
        List<string> regexPatterns = new List<string> { @"\d{3}-\d{2}-\d{4}", @"[A-Z]{2}[0-9]{6}" };
        try
        {
            string[] files = Directory.GetFiles("./input", "*.png");
            RecognitionSettings settings = new RecognitionSettings();
            settings.Language = Language.English;
            AsposeOcr ocr = new AsposeOcr();
            foreach (string file in files)
            {
                foreach (string keyword in keywords)
                {
                    bool found = ocr.ImageHasText(file, keyword, settings);
                    if (found)
                        File.AppendAllText("search_log.csv", $"{file},{keyword},found\n");
                }
                foreach (string pattern in regexPatterns)
                {
                    bool found = ocr.ImageHasText(file, pattern, settings);
                    if (found)
                        File.AppendAllText("search_log.csv", $"{file},{pattern},found\n");
                }
            }
        }
        catch (Exception ex)
        {
            File.AppendAllText("search_errors.log", ex.Message + Environment.NewLine);
        }
    }
}

Use Cases and Applications

Compliance Audits

Automatically check scanned archives for blacklisted words or sensitive patterns.

HR, Legal, and Security

Detect presence of confidential phrases, employee names, or PII in onboarding or evidence files.

Trend and Frequency Analysis

Count and report frequency of keywords over time in large document sets.

Common Challenges and Solutions

Challenge 1: False Positives

Solution: Refine keywords and regex; review edge cases manually.

Challenge 2: Large Batch Size

Solution: Use parallel processing and robust error handling.

Challenge 3: Multiple Languages

Solution: Adjust recognition settings and keyword lists per language batch.

Performance Considerations

  • Batch jobs may run long for large archives—monitor CPU, disk, and logs
  • Parallelize if required for high throughput
  • Log all results for review and compliance

Best Practices

  1. Curate and update keyword lists regularly
  2. Automate error logging and reporting
  3. Test on representative archive samples
  4. Secure logs and search results

Advanced Scenarios

Scenario 1: Search and Highlight Results in Output PDF

Export images with found keywords highlighted (custom post-processing).

Scenario 2: Schedule Regular Batch Keyword Audits

Automate job to run nightly or weekly for compliance.

Conclusion

Aspose.OCR Image Text Finder for .NET enables powerful, automated batch keyword and pattern searching—supporting compliance, security, and trend analysis across image archives.

See Aspose.OCR for .NET API Reference for advanced text search examples.

 English