How to Convert PDF to Image in .NET?

What are the most common PDF to image use cases?

PDF to image conversion serves critical purposes in document processing workflows. Common use cases include:

• Creating thumbnail previews for document management systems
• Extracting images from PDF documents
• Generating image-based previews for web display
• Processing single PDF pages for OCR workflows
• Enabling document sharing on platforms without PDF support
• Creating PDF reports that need image thumbnails
• Converting ASPX pages to images for preview generation
• Processing HTML files to PDF before image extraction

Why is containerized deployment important for PDF conversion?

Many compliance and archival systems require documents in specific image formats like TIFF for long-term storage, particularly for PDF/A compliance. For PDF/A-3 and ZUGFeRD invoicing requirements, image conversion provides additional flexibility. You need a reliable .NET wrapper that works seamlessly across different environments, especially in containerized deployments where managing dependencies is crucial. The ability to run IronPDF as a remote container improves scalability for high-volume batch processing scenarios.

What is the simplest way to convert PDF to images?

For the simplest PDF to image conversion scenario, you can convert an entire PDF document to high-quality PNG or JPG images with just two lines of code:

var pdf = PdfDocument.FromFile("invoice.pdf");
pdf.RasterizeToImageFiles(@"C:\images\folder\page_*.png");

var pdf = PdfDocument.FromFile("invoice.pdf");
pdf.RasterizeToImageFiles(@"C:\images\folder\page_*.png");

Dim pdf = PdfDocument.FromFile("invoice.pdf")
pdf.RasterizeToImageFiles("C:\images\folder\page_*.png")

This code loads a single PDF file using the PdfDocument.FromFile method and converts all PDF pages to PNG image files. The RasterizeToImageFiles method automatically handles multiple pages in PDF documents, creating separate image files for each page with sequential numbering in the output folder. Note that the asterisk in the file path acts as a placeholder for automatic page numbering. For more advanced scenarios, you can add, copy & delete PDF pages before conversion or merge or split PDFs to control the output structure.

How do I implement async conversion for better performance?

For production deployments, consider using async methods for better performance, especially when implementing async & multithreading patterns:

// Async conversion for better performance in containerized environments
public async Task ConvertPdfToImagesAsync(string inputPath, string outputPattern)
{
    var pdf = await PdfDocument.FromFileAsync(inputPath);
    await pdf.RasterizeToImageFilesAsync(outputPattern);
}

// Async conversion for better performance in containerized environments
public async Task ConvertPdfToImagesAsync(string inputPath, string outputPattern)
{
    var pdf = await PdfDocument.FromFileAsync(inputPath);
    await pdf.RasterizeToImageFilesAsync(outputPattern);
}

' Async conversion for better performance in containerized environments
Public Async Function ConvertPdfToImagesAsync(inputPath As String, outputPattern As String) As Task
    Dim pdf = Await PdfDocument.FromFileAsync(inputPath)
    Await pdf.RasterizeToImageFilesAsync(outputPattern)
End Function

This approach is particularly beneficial when deploying to Azure or deploying to AWS cloud environments where resource optimization is crucial. For improved performance, consider implementing custom logging to monitor conversion metrics.

Input

Output

How Do I Convert Selected Pages from PDF to JPG?

To convert specific PDF pages rather than the entire PDF document, use the page range parameter:

// Event handler example for Windows Forms application
private void ConvertButton_Click(object sender, EventArgs e)
{
    var pdf = PdfDocument.FromFile("report.pdf");
    var pageRange = Enumerable.Range(0, 5); // First 5 pages
    pdf.RasterizeToImageFiles(
        @"C:\output\page_*.jpg",
        pageRange,
        1920,   // Width in pixels
        1080,   // Height in pixels
        IronPdf.Imaging.ImageType.Jpeg,
        150     // Image DPI setting
    );
}

// Event handler example for Windows Forms application
private void ConvertButton_Click(object sender, EventArgs e)
{
    var pdf = PdfDocument.FromFile("report.pdf");
    var pageRange = Enumerable.Range(0, 5); // First 5 pages
    pdf.RasterizeToImageFiles(
        @"C:\output\page_*.jpg",
        pageRange,
        1920,   // Width in pixels
        1080,   // Height in pixels
        IronPdf.Imaging.ImageType.Jpeg,
        150     // Image DPI setting
    );
}

' Event handler example for Windows Forms application
Private Sub ConvertButton_Click(sender As Object, e As EventArgs)
    Dim pdf = PdfDocument.FromFile("report.pdf")
    Dim pageRange = Enumerable.Range(0, 5) ' First 5 pages
    pdf.RasterizeToImageFiles(
        "C:\output\page_*.jpg",
        pageRange,
        1920,   ' Width in pixels
        1080,   ' Height in pixels
        IronPdf.Imaging.ImageType.Jpeg,
        150     ' Image DPI setting
    )
End Sub

This sample converts the first five pages to JPEG format with specified dimensions. The method parameters give you complete control:

• Define output path pattern for naming conventions
• Select single or multiple pages
• Set maximum width and height while maintaining aspect ratio
• Choose image format (JPEG, PNG, TIFF, BMP)
• Specify DPI resolution for print-quality output

The rasterization process preserves text clarity and graphics quality. For documents with backgrounds & foregrounds, conversion maintains all visual elements. You can also draw line & rectangle shapes or draw text & bitmap overlays before conversion.

How do I implement health checks for containerized environments?

For containerized environments, consider implementing health check endpoints, especially when creating PDFs in Blazor Servers:

// Health check endpoint for Kubernetes readiness probe
[HttpGet("/health/pdf-converter")]
public IActionResult HealthCheck()
{
    try
    {
        // Test basic PDF functionality
        var testPdf = new PdfDocument("<p>Health Check</p>");
        var imageBytes = testPdf.RasterizeToImageFiles(ImageType.Png);
        return Ok(new { status = "healthy", timestamp = DateTime.UtcNow });
    }
    catch (Exception ex)
    {
        return StatusCode(503, new { status = "unhealthy", error = ex.Message });
    }
}

// Health check endpoint for Kubernetes readiness probe
[HttpGet("/health/pdf-converter")]
public IActionResult HealthCheck()
{
    try
    {
        // Test basic PDF functionality
        var testPdf = new PdfDocument("<p>Health Check</p>");
        var imageBytes = testPdf.RasterizeToImageFiles(ImageType.Png);
        return Ok(new { status = "healthy", timestamp = DateTime.UtcNow });
    }
    catch (Exception ex)
    {
        return StatusCode(503, new { status = "unhealthy", error = ex.Message });
    }
}

' Health check endpoint for Kubernetes readiness probe
<HttpGet("/health/pdf-converter")>
Public Function HealthCheck() As IActionResult
    Try
        ' Test basic PDF functionality
        Dim testPdf As New PdfDocument("<p>Health Check</p>")
        Dim imageBytes = testPdf.RasterizeToImageFiles(ImageType.Png)
        Return Ok(New With {Key .status = "healthy", Key .timestamp = DateTime.UtcNow})
    Catch ex As Exception
        Return StatusCode(503, New With {Key .status = "unhealthy", Key .error = ex.Message})
    End Try
End Function

This pattern is essential for Kubernetes deployment monitoring and ensures your PDF viewing in MAUI applications remain responsive.

When Should I Convert Website URLs to Images Instead of Direct PDFs?

IronPDF can render web pages to PDF and then convert to image files using the URL to PDF functionality:

var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderUrlAsPdf("___PROTECTED_URL_52___");
pdf.RasterizeToImageFiles(@"C:\web\screenshot_*.png");

var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderUrlAsPdf("___PROTECTED_URL_52___");
pdf.RasterizeToImageFiles(@"C:\web\screenshot_*.png");

Dim renderer As New ChromePdfRenderer()
Dim pdf = renderer.RenderUrlAsPdf("___PROTECTED_URL_52___")
pdf.RasterizeToImageFiles("C:\web\screenshot_*.png")

This approach captures website content exactly as it appears in Chrome browser, then converts each page to PNG images. The ChromePdfRenderer ensures accurate rendering of modern web technologies including JavaScript, CSS3, and responsive layouts, making it perfect for creating website screenshots or archiving web content. The render method supports base URLs & asset encoding and cookies for authenticated content. For complex sites, use WaitFor to delay PDF render until all content loads.

What rendering options should I configure for production?

For production deployments, configure rendering delays and timeouts, especially when working with TLS website & system logins:

// Configure renderer for reliable containerized deployment
var renderer = new ChromePdfRenderer
{
    RenderingOptions = new ChromePdfRenderOptions
    {
        RenderDelay = 2000, // Wait 2 seconds for dynamic content
        Timeout = 30000,    // 30-second timeout for slow networks
        EnableJavaScript = true,
        ViewPortWidth = 1920,
        ViewPortHeight = 1080
    }
};

// Add custom HTTP headers for authentication if needed
renderer.RenderingOptions.CustomCssUrl = "___PROTECTED_URL_53___";

// Configure renderer for reliable containerized deployment
var renderer = new ChromePdfRenderer
{
    RenderingOptions = new ChromePdfRenderOptions
    {
        RenderDelay = 2000, // Wait 2 seconds for dynamic content
        Timeout = 30000,    // 30-second timeout for slow networks
        EnableJavaScript = true,
        ViewPortWidth = 1920,
        ViewPortHeight = 1080
    }
};

// Add custom HTTP headers for authentication if needed
renderer.RenderingOptions.CustomCssUrl = "___PROTECTED_URL_53___";

' Configure renderer for reliable containerized deployment
Dim renderer = New ChromePdfRenderer With {
    .RenderingOptions = New ChromePdfRenderOptions With {
        .RenderDelay = 2000, ' Wait 2 seconds for dynamic content
        .Timeout = 30000,    ' 30-second timeout for slow networks
        .EnableJavaScript = True,
        .ViewPortWidth = 1920,
        .ViewPortHeight = 1080
    }
}

' Add custom HTTP headers for authentication if needed
renderer.RenderingOptions.CustomCssUrl = "___PROTECTED_URL_53___"

For improved security, implement HTTP request header authentication and manage PDF permissions passwords. The renderer supports fonts (web & icon) and can manage fonts for consistent rendering across platforms.

Input

Output

Which image format should I choose for my use case?

PNG Format - Ideal for documents requiring transparency or lossless compression. Perfect for technical drawings, screenshots, and documents where text clarity is crucial. PNG ensures no quality loss during PDF rasterization and performs well for web display. The format suits watermarked documents and when you need to stamp new content onto images. PNG works excellently with grayscale conversions and maintains quality when implementing custom watermarks.

JPEG/JPG Format - Best for photographs and complex images where smaller file sizes are needed. The PDF to JPG converter supports quality adjustment for balancing file size versus image clarity. Implement compression strategies for optimal results:

// Improve JPEG conversion for web deployment
public void ConvertToOptimizedJpeg(string pdfPath, int quality = 85)
{
    var pdf = PdfDocument.FromFile(pdfPath);

    // Configure JPEG-specific settings
    var jpegEncoder = new JpegEncoder { Quality = quality };

    pdf.RasterizeToImageFiles(
        @"optimized_*.jpg",
        imageType: ImageType.Jpeg,
        dpi: 96  // Web-improve DPI
    );
}

// Improve JPEG conversion for web deployment
public void ConvertToOptimizedJpeg(string pdfPath, int quality = 85)
{
    var pdf = PdfDocument.FromFile(pdfPath);

    // Configure JPEG-specific settings
    var jpegEncoder = new JpegEncoder { Quality = quality };

    pdf.RasterizeToImageFiles(
        @"optimized_*.jpg",
        imageType: ImageType.Jpeg,
        dpi: 96  // Web-improve DPI
    );
}

' Improve JPEG conversion for web deployment
Public Sub ConvertToOptimizedJpeg(pdfPath As String, Optional quality As Integer = 85)
    Dim pdf = PdfDocument.FromFile(pdfPath)

    ' Configure JPEG-specific settings
    Dim jpegEncoder As New JpegEncoder With {.Quality = quality}

    pdf.RasterizeToImageFiles(
        "optimized_*.jpg",
        imageType:=ImageType.Jpeg,
        dpi:=96  ' Web-improve DPI
    )
End Sub

For documents requiring linearize PDFs for fast web viewing, JPEG conversion provides efficient alternatives. The format works well with page numbers and page breaks for multi-page conversions.

How do I create multi-page TIFF files for archival?

TIFF Format - Excellent for archival purposes, supporting both single and multi-page TIFF documents. IronPDF's ability to create multi-page TIFF files from PDF pages is particularly valuable:

// Convert PDF to multi-page TIFF - all pages in single file
var pdf = PdfDocument.FromFile("multipage.pdf");
pdf.ToMultiPageTiffImage(@"C:\archive\document.tiff", null, null, 300);
// Process complete - single TIFF contains all pages
Console.WriteLine("PDF converted to multi-page TIFF");

// Convert PDF to multi-page TIFF - all pages in single file
var pdf = PdfDocument.FromFile("multipage.pdf");
pdf.ToMultiPageTiffImage(@"C:\archive\document.tiff", null, null, 300);
// Process complete - single TIFF contains all pages
Console.WriteLine("PDF converted to multi-page TIFF");

' Convert PDF to multi-page TIFF - all pages in single file
Dim pdf = PdfDocument.FromFile("multipage.pdf")
pdf.ToMultiPageTiffImage("C:\archive\document.tiff", Nothing, Nothing, 300)
' Process complete - single TIFF contains all pages
Console.WriteLine("PDF converted to multi-page TIFF")

This creates a single TIFF file containing all PDF pages, maintaining document integrity while meeting archival standards. The 300 DPI setting ensures high-resolution output suitable for long-term storage and compliance. Multi-page TIFF is especially useful for:

• Fax systems requiring single-file documents
• Medical imaging archival
• Legal document storage where pages must remain together

This feature distinguishes IronPDF from simpler conversion tools and supports PDF/UA format docs accessibility compliance and flatten PDFs for archival.

BMP Format - Provides uncompressed bitmap output when maximum quality without compression artifacts is required for System.Drawing workflows. Consider using custom paper sizes for specialized requirements. BMP format works well with print to a physical printer scenarios or when you need to transform PDF pages for precise positioning.

What DPI settings work best for different scenarios?

Resolution control through DPI settings allows optimization for different scenarios:

• 72-96 DPI for web display and thumbnail generation
• 150-200 DPI for general document viewing
• 300+ DPI for print-quality output and OCR processing

The image DPI directly affects file size and quality. For export different PDF versions, appropriate DPI selection is crucial. When implementing fit to paper & zoom features, DPI settings determine output clarity. For containerized deployments, implement resource limits:

// Docker-improve conversion with memory management
public class PdfImageConverter : IDisposable
{
    private readonly ChromePdfRenderer _renderer;

    public PdfImageConverter()
    {
        _renderer = new ChromePdfRenderer
        {
            RenderingOptions = new ChromePdfRenderOptions
            {
                // Improve for container memory limits
                CreatePdfFormsFromHtml = false,
                EnableJavaScript = false,
                RenderDelay = 0
            }
        };
    }

    public async Task<byte[]> ConvertToImageBytesAsync(string pdfPath, int pageIndex = 0)
    {
        using var pdf = await PdfDocument.FromFileAsync(pdfPath);
        var images = await pdf.RasterizeToBitmapsAsync(new[] { pageIndex }, 150);

        using var ms = new MemoryStream();
        images[0].Save(ms, ImageFormat.Png);
        return ms.ToArray();
    }

    public void Dispose()
    {
        _renderer?.Dispose();
    }
}

// Docker-improve conversion with memory management
public class PdfImageConverter : IDisposable
{
    private readonly ChromePdfRenderer _renderer;

    public PdfImageConverter()
    {
        _renderer = new ChromePdfRenderer
        {
            RenderingOptions = new ChromePdfRenderOptions
            {
                // Improve for container memory limits
                CreatePdfFormsFromHtml = false,
                EnableJavaScript = false,
                RenderDelay = 0
            }
        };
    }

    public async Task<byte[]> ConvertToImageBytesAsync(string pdfPath, int pageIndex = 0)
    {
        using var pdf = await PdfDocument.FromFileAsync(pdfPath);
        var images = await pdf.RasterizeToBitmapsAsync(new[] { pageIndex }, 150);

        using var ms = new MemoryStream();
        images[0].Save(ms, ImageFormat.Png);
        return ms.ToArray();
    }

    public void Dispose()
    {
        _renderer?.Dispose();
    }
}

Imports System
Imports System.IO
Imports System.Drawing.Imaging
Imports System.Threading.Tasks

Public Class PdfImageConverter
    Implements IDisposable

    Private ReadOnly _renderer As ChromePdfRenderer

    Public Sub New()
        _renderer = New ChromePdfRenderer With {
            .RenderingOptions = New ChromePdfRenderOptions With {
                .CreatePdfFormsFromHtml = False,
                .EnableJavaScript = False,
                .RenderDelay = 0
            }
        }
    End Sub

    Public Async Function ConvertToImageBytesAsync(pdfPath As String, Optional pageIndex As Integer = 0) As Task(Of Byte())
        Using pdf = Await PdfDocument.FromFileAsync(pdfPath)
            Dim images = Await pdf.RasterizeToBitmapsAsync(New Integer() {pageIndex}, 150)

            Using ms As New MemoryStream()
                images(0).Save(ms, ImageFormat.Png)
                Return ms.ToArray()
            End Using
        End Using
    End Function

    Public Sub Dispose() Implements IDisposable.Dispose
        _renderer?.Dispose()
    End Sub
End Class

This implementation pattern is essential for load PDFs from memory scenarios and when you need to export PDFs to memory for efficient resource usage. The approach works smoothly with save & export PDF documents workflows.

How can I implement production-ready batch processing?

For production deployments, implement monitoring and batch processing with OpenAI for PDF integration for intelligent document processing:

// Production-ready batch conversion service
public class BatchImageConversionService
{
    private readonly ILogger<BatchImageConversionService> _logger;
    private readonly SemaphoreSlim _semaphore;

    public BatchImageConversionService(ILogger<BatchImageConversionService> logger)
    {
        _logger = logger;
        _semaphore = new SemaphoreSlim(Environment.ProcessorCount);
    }

    public async Task<ConversionResult> ConvertBatchAsync(
        IEnumerable<string> pdfPaths, 
        ConversionOptions options)
    {
        var tasks = pdfPaths.Select(path => ConvertWithThrottlingAsync(path, options));
        var results = await Task.WhenAll(tasks);

        return new ConversionResult
        {
            TotalFiles = results.Length,
            SuccessCount = results.Count(r => r.Success),
            FailedFiles = results.Where(r => !r.Success).Select(r => r.FilePath)
        };
    }

    private async Task<FileConversionResult> ConvertWithThrottlingAsync(
        string pdfPath, 
        ConversionOptions options)
    {
        await _semaphore.WaitAsync();
        try
        {
            var stopwatch = Stopwatch.StartNew();
            var pdf = await PdfDocument.FromFileAsync(pdfPath);

            await pdf.RasterizeToImageFilesAsync(
                Path.Combine(options.OutputDirectory, $"{Path.GetFileNameWithoutExtension(pdfPath)}_*.{options.Format}"),
                imageType: options.Format,
                dpi: options.Dpi
            );

            _logger.LogInformation(
                "Converted {FileName} in {ElapsedMs}ms", 
                Path.GetFileName(pdfPath), 
                stopwatch.ElapsedMilliseconds
            );

            return new FileConversionResult { Success = true, FilePath = pdfPath };
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to convert {FileName}", Path.GetFileName(pdfPath));
            return new FileConversionResult { Success = false, FilePath = pdfPath, Error = ex.Message };
        }
        finally
        {
            _semaphore.Release();
        }
    }
}

// Production-ready batch conversion service
public class BatchImageConversionService
{
    private readonly ILogger<BatchImageConversionService> _logger;
    private readonly SemaphoreSlim _semaphore;

    public BatchImageConversionService(ILogger<BatchImageConversionService> logger)
    {
        _logger = logger;
        _semaphore = new SemaphoreSlim(Environment.ProcessorCount);
    }

    public async Task<ConversionResult> ConvertBatchAsync(
        IEnumerable<string> pdfPaths, 
        ConversionOptions options)
    {
        var tasks = pdfPaths.Select(path => ConvertWithThrottlingAsync(path, options));
        var results = await Task.WhenAll(tasks);

        return new ConversionResult
        {
            TotalFiles = results.Length,
            SuccessCount = results.Count(r => r.Success),
            FailedFiles = results.Where(r => !r.Success).Select(r => r.FilePath)
        };
    }

    private async Task<FileConversionResult> ConvertWithThrottlingAsync(
        string pdfPath, 
        ConversionOptions options)
    {
        await _semaphore.WaitAsync();
        try
        {
            var stopwatch = Stopwatch.StartNew();
            var pdf = await PdfDocument.FromFileAsync(pdfPath);

            await pdf.RasterizeToImageFilesAsync(
                Path.Combine(options.OutputDirectory, $"{Path.GetFileNameWithoutExtension(pdfPath)}_*.{options.Format}"),
                imageType: options.Format,
                dpi: options.Dpi
            );

            _logger.LogInformation(
                "Converted {FileName} in {ElapsedMs}ms", 
                Path.GetFileName(pdfPath), 
                stopwatch.ElapsedMilliseconds
            );

            return new FileConversionResult { Success = true, FilePath = pdfPath };
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to convert {FileName}", Path.GetFileName(pdfPath));
            return new FileConversionResult { Success = false, FilePath = pdfPath, Error = ex.Message };
        }
        finally
        {
            _semaphore.Release();
        }
    }
}

Imports System
Imports System.Collections.Generic
Imports System.IO
Imports System.Linq
Imports System.Threading
Imports System.Threading.Tasks

Public Class BatchImageConversionService
    Private ReadOnly _logger As ILogger(Of BatchImageConversionService)
    Private ReadOnly _semaphore As SemaphoreSlim

    Public Sub New(logger As ILogger(Of BatchImageConversionService))
        _logger = logger
        _semaphore = New SemaphoreSlim(Environment.ProcessorCount)
    End Sub

    Public Async Function ConvertBatchAsync(pdfPaths As IEnumerable(Of String), options As ConversionOptions) As Task(Of ConversionResult)
        Dim tasks = pdfPaths.Select(Function(path) ConvertWithThrottlingAsync(path, options))
        Dim results = Await Task.WhenAll(tasks)

        Return New ConversionResult With {
            .TotalFiles = results.Length,
            .SuccessCount = results.Count(Function(r) r.Success),
            .FailedFiles = results.Where(Function(r) Not r.Success).Select(Function(r) r.FilePath)
        }
    End Function

    Private Async Function ConvertWithThrottlingAsync(pdfPath As String, options As ConversionOptions) As Task(Of FileConversionResult)
        Await _semaphore.WaitAsync()
        Try
            Dim stopwatch = Stopwatch.StartNew()
            Dim pdf = Await PdfDocument.FromFileAsync(pdfPath)

            Await pdf.RasterizeToImageFilesAsync(
                Path.Combine(options.OutputDirectory, $"{Path.GetFileNameWithoutExtension(pdfPath)}_*.{options.Format}"),
                imageType:=options.Format,
                dpi:=options.Dpi
            )

            _logger.LogInformation(
                "Converted {FileName} in {ElapsedMs}ms",
                Path.GetFileName(pdfPath),
                stopwatch.ElapsedMilliseconds
            )

            Return New FileConversionResult With {.Success = True, .FilePath = pdfPath}
        Catch ex As Exception
            _logger.LogError(ex, "Failed to convert {FileName}", Path.GetFileName(pdfPath))
            Return New FileConversionResult With {.Success = False, .FilePath = pdfPath, .Error = ex.Message}
        Finally
            _semaphore.Release()
        End Try
    End Function
End Class

This service pattern supports parallel PDF generation and can be extended with edit & sign revision history tracking. For improved monitoring, implement set & edit metadata to track conversion details. The service can also integrate with add a table of contents generation and outlines & bookmarks management.

What performance optimizations are available?

The library's performance optimization features include automatic memory management for large documents, parallel processing support for batch operations, and efficient caching of rendering resources. For containerized deployments, consider using the IronPDF Engine as a separate microservice to isolate resource usage and improve scalability. When working with large documents, sanitize PDF content to remove unnecessary elements. For sensitive data, implement redact text & regions before conversion. The library supports render WebGL sites and can handle signing PDFs with digital certificates, even supporting signing PDFs with HSM for improved security.

Additional optimization techniques include:

• Using rotate text and pages to correct orientation
• Implementing support UTF-8 and international languages for global deployments
• Use Chrome PDF rendering engine capabilities

For document preparation, you can replace text in PDF, convert XML to PDF, convert DOCX to PDF, convert MD to PDF, or convert RTF to PDF before image extraction.