Unsupported Image Format Exception Occurs When Using PdfStreamWriter

Updated on Sep 17, 2026

Environment

Version	Product	Author
2026.3.810	RadPdfProcessing	Desislava Yordanova

Description

When you add an image to a PDF document, PdfProcessing can throw NotSupportedImageFormatException: 'Not supported image format.'. The exception usually occurs for one of the following reasons:

• You create ImageSource with an overload that is not available for your target framework. For cross-platform projects, use the ImageSource(Stream) constructor.
• You export an image format other than JPEG or JPEG2000 without configuring the cross-platform image extensions.
• You pass a RadFixedDocument to PdfStreamWriter. The writer accepts a generated RadFixedPage, not a complete document.

Solution

Use RadFixedDocument with PdfFormatProvider when you need to create or edit a complete document. Use PdfStreamWriter when you need to write individual pages with a low-memory streaming workflow.

Configure Image Processing for Cross-Platform Projects

For cross-platform targets, add the Telerik.Documents.ImageUtils NuGet package and the platform-specific SkiaSharp.NativeAssets.* package. The ImageUtils package provides default implementations for ImagePropertiesResolver and JpegImageConverter. Configure both implementations before you create or export the image:

csharp

Telerik.Documents.ImageUtils.ImagePropertiesResolver defaultImagePropertiesResolver = new Telerik.Documents.ImageUtils.ImagePropertiesResolver();
Telerik.Documents.Extensibility.FixedExtensibilityManager.ImagePropertiesResolver = defaultImagePropertiesResolver;

Telerik.Documents.ImageUtils.JpegImageConverter defaultJpegImageConverter = new Telerik.Documents.ImageUtils.JpegImageConverter();
Telerik.Documents.Extensibility.FixedExtensibilityManager.JpegImageConverter = defaultJpegImageConverter;

Configure the image extensions before export. If both ImagePropertiesResolver and JpegImageConverter remain null, export throws InvalidOperationException.

Create a Complete PDF Document

Use RadFixedDocument and PdfFormatProvider when you need to add multiple pages, edit document content, or access document-level properties:

csharp

RadFixedDocument document = new RadFixedDocument();
RadFixedPage page = document.Pages.AddPage();

using (Stream imageStream = File.OpenRead("path-to-your-image.jpg"))
{
    ImageSource imageSource = new ImageSource(imageStream);
    page.Content.AddImage(imageSource);

    PdfFormatProvider provider = new PdfFormatProvider();
    using (Stream output = File.OpenWrite("output.pdf"))
    {
        provider.Export(document, output, TimeSpan.FromSeconds(10));
    }
}

ImageSource(Stream) reads image data from the supplied stream. Keep the stream open until the image is added and the document is exported.

Write a Page with PdfStreamWriter

Use PdfStreamWriter for a low-memory workflow. Create a RadFixedPage, add the image to that page, and pass the page to WritePage:

csharp

using (Stream imageStream = File.OpenRead("path-to-your-image.jpg"))
{
    RadFixedDocument document = new RadFixedDocument();
    RadFixedPage page = document.Pages.AddPage();
    page.Content.AddImage(new ImageSource(imageStream));

    using (Stream output = File.OpenWrite("output.pdf"))
    using (PdfStreamWriter writer = new PdfStreamWriter(output))
    {
        writer.WritePage(page);
    }
}

Do not pass RadFixedDocument to WritePage. To write an existing page, pass its RadFixedPage instance instead.

If the exception continues, verify the following items:

1. Confirm that the input stream contains a valid image and that its position is set to 0 before you create ImageSource.
2. Use ImageSource(Stream) for cross-platform projects instead of a BitmapSource overload.
3. Reference Telerik.Documents.ImageUtils and the required native SkiaSharp package when the image format or image quality requires conversion.
4. Configure FixedExtensibilityManager before exporting the PDF.
5. Keep the image stream open until PdfProcessing finishes reading the image.

For package requirements and custom image processing implementations, see Images.

See Also

• PdfStreamWriter overview
• RadFixedDocument model
• RadFixedPage model
• ImageSource constructors
• PdfFormatProvider
• Cross-platform image processing