Convert PDF to PDF/A formats

Aspose.PDF for .NET allows you to convert a PDF file to a PDF/A compliant PDF file. Before doing so, the file must be validated. This topic explains how.

Please note we follow Adobe Preflight and veraPDF for validating PDF/A conformance. All tools on the market have their own “representation” of PDF/A conformance. Please check this article on PDF/A validation tools for reference. We chose Adobe products for verifying how Aspose.PDF produces PDF files because Adobe is at the center of everything connected to PDF.

Convert the file using the Document class Convert method. Before converting the PDF to PDF/A compliant file, validate the PDF using the Validate method. The validation result is stored in an XML file and then this result is also passed to the Convert method. You can also specify the action for the elements which cannot be converted using the ConvertErrorAction enumeration.

Try to convert PDF to PDF/A online

Aspose.PDF for .NET presents you online free application “PDF to PDF/A-1A”, where you may try to investigate the functionality and quality it works.

The following code snippet also work with Aspose.PDF.Drawing library.

Supported standards

We support the following standards: PDF/A-1b, PDF/A-1a, PDF/A-2b, PDF/A-2u, PDF/A-2a, PDF/A-3b, PDF/A-3u, PDF/A-3a, PDF/A-4, PDF/A-4e, PDF/A-4f.

Convert PDF file to PDF/A-1b

The following code snippet shows how to convert PDF files to PDF/A-1b compliant PDF.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ConvertPdfToPdfA()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();
    
    // Open document
    using (var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf"))
    {
        // Convert to PDF/A compliant document
        // During conversion process, the validation is also performed
        document.Convert(dataDir + "PDFA1bConversionLog.xml", Aspose.Pdf.PdfFormat.PDF_A_1B, Aspose.Pdf.ConvertErrorAction.Delete);
        
        // Save output document
        document.Save(dataDir + "PDFToPDFA_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ConvertPdfToPdfA()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();
    
    // Open document
    using var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf");

    // Convert to PDF/A compliant document
    // During conversion process, the validation is also performed
    document.Convert(dataDir + "PDFA1bConversionLog.xml", Aspose.Pdf.PdfFormat.PDF_A_1B, Aspose.Pdf.ConvertErrorAction.Delete);
    
    // Save output document
    document.Save(dataDir + "PDFToPDFA_out.pdf");
}

To perform validation only, use the following line of code:

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ValidatePdfAStandard()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();
    
    // Open document
    using (var document = new Aspose.Pdf.Document(dataDir + "ValidatePDFAStandard.pdf"))
    {
        // Validate PDF for PDF/A-1a
        document.Validate(dataDir + "ValidationResultA1b.xml", Aspose.Pdf.PdfFormat.PDF_A_1B);
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
       
private static void ValidatePdfAStandard()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Open document
    using var document = new Aspose.Pdf.Document(dataDir + "ValidatePDFAStandard.pdf");

    // Validate PDF for PDF/A-1a
    document.Validate(dataDir + "ValidationResultA1b.xml", Aspose.Pdf.PdfFormat.PDF_A_1B);
}

Convert PDF file to PDF/A-3b

Aspose.PDF for .NET also supports the feature to convert a PDF file to PDF/A-3b format.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ConvertPdfToPdfA3b()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();
    
    // Open document
    using (var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf"))
    {
        // Convert to PDF/A compliant document, log file is omitted
        document.Convert(Stream.Null, Aspose.Pdf.PdfFormat.PDF_A_3B, Aspose.Pdf.ConvertErrorAction.Delete);
        
        // Save output document
        document.Save(dataDir + "PDFToPDFA3b_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ConvertPdfToPdfA3b()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    // Open document
    using var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf");

    // Convert to PDF/A compliant document, log file is omitted
    document.Convert(Stream.Null, Aspose.Pdf.PdfFormat.PDF_A_3B, Aspose.Pdf.ConvertErrorAction.Delete);

    // Save output document
    document.Save(dataDir + "PDFToPDFA3b_out.pdf");
}

Convert PDF file to PDF/A-4

Aspose.PDF for .NET also supports the feature to convert a PDF file to PDF/A-4 format.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ConvertPdfToPdfA4()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();
    
    // Open document
    using (var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf"))
    {
        // If the document version is less than PDF-2.0, it must be converted to PDF-2.0
        document.Convert(Stream.Null, Aspose.Pdf.PdfFormat.v_2_0, Aspose.Pdf.ConvertErrorAction.Delete);
    
        // Convert to the PDF/A-4 format
        document.Convert(dataDir + "PDFA4ConversionLog.xml", Aspose.Pdf.PdfFormat.PDF_A_4, Aspose.Pdf.ConvertErrorAction.Delete);

        // Save output document
        document.Save(dataDir + "PDFToPDFA4_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ConvertPdfToPdfA4()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    // Open document
    using var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf");

    // If the document version is less than PDF-2.0, it must be converted to PDF-2.0
    document.Convert(Stream.Null, Aspose.Pdf.PdfFormat.v_2_0, Aspose.Pdf.ConvertErrorAction.Delete);

    // Convert to the PDF/A-4 format
    document.Convert(dataDir + "PDFA4ConversionLog.xml", Aspose.Pdf.PdfFormat.PDF_A_4, Aspose.Pdf.ConvertErrorAction.Delete);

    // Save output document
    document.Save(dataDir + "PDFToPDFA4_out.pdf");
}

Add Attachment to PDF/A file

In case you have a requirement to attach files to a PDF/A compliant document, then we recommend using a PDF_A_3A value from the Aspose.PDF.PdfFormat enumeration. PDF/A-3a is the format that provides the feature to attach any file format as an attachment to a PDF/A compliant file.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void AddAttachmentToPdfA()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();
    
    // Instantiate Document instance to load existing file
    using (var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf"))
    {
        // Setup new file to be added as attachment
        using (var fileSpecification = new Aspose.Pdf.FileSpecification(dataDir + "aspose-logo.jpg", "Large Image file"))
        {
            // Add attachment to document's attachment collection
            document.EmbeddedFiles.Add(fileSpecification);

            // Perform conversion to PDF/A-3a, so that the attachment is included in the resultant file
            document.Convert(dataDir + "PDFA3aConversionLog.xml", Aspose.Pdf.PdfFormat.PDF_A_3A, Aspose.Pdf.ConvertErrorAction.Delete);

            // Save resultant file
            document.Save(dataDir + "AddAttachmentToPDFA_out.pdf");
        }
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void AddAttachmentToPdfA()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    // Instantiate Document instance to load existing file
    using var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf");

    // Setup new file to be added as attachment
    using var fileSpecification = new Aspose.Pdf.FileSpecification(dataDir + "aspose-logo.jpg", "Large Image file");

    // Add attachment to document's attachment collection
    document.EmbeddedFiles.Add(fileSpecification);

    // Perform conversion to PDF/A-3a, so that the attachment is included in the resultant file
    document.Convert(dataDir + "PDFA3aConversionLog.xml", Aspose.Pdf.PdfFormat.PDF_A_3A, Aspose.Pdf.ConvertErrorAction.Delete);

    // Save resultant file
    document.Save(dataDir + "AddAttachmentToPDFA_out.pdf");
}

Replace missing fonts with alternative fonts

As per PDF/A standards, fonts should be embedded in a PDF/A document. However, if the fonts are not embedded in the source document and don’t exist on the machine then PDF/A conversion fails. In this case, it’s necessary to substitute missing fonts with some alternative fonts existing in the machine. Missing fonts can be substituted using the SimpleFontSubsitution class during the PDF to PDF/A conversion.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ReplaceMissingFonts()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    try
    {
        // Check whether a font, used in the source document, is installed in the system
        Aspose.Pdf.Text.FontRepository.FindFont("AgencyFB");
    }
    catch (Aspose.Pdf.FontNotFoundException)
    {
        // Font is missing on the destination machine. Replace it with the Arial font installed in the system
        var fontSubstitution = new Aspose.Pdf.Text.SimpleFontSubstitution("AgencyFB", "Arial");
        Aspose.Pdf.Text.FontRepository.Substitutions.Add(fontSubstitution);
    }

    // Open document
    using (var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf"))
    {
        // During the conversion, the missing font will be replaced with the substitution one
        document.Convert(dataDir + "ReplaceMissingFonts.xml", PdfFormat.PDF_A_1B, ConvertErrorAction.Delete);

        // Save output document
        document.Save(dataDir + "ReplaceMissingFonts_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET

private static void ReplaceMissingFonts()
{
    // The path to the documents directory
    string dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    try
    {
        // Check whether a font, used in the source document, is installed in the system
        Aspose.Pdf.Text.FontRepository.FindFont("AgencyFB");
    }
    catch (Aspose.Pdf.FontNotFoundException)
    {
        // Font is missing on the destination machine. Replace it with the Arial font installed in the system
        var fontSubstitution = new Aspose.Pdf.Text.SimpleFontSubstitution("AgencyFB", "Arial");
        Aspose.Pdf.Text.FontRepository.Substitutions.Add(fontSubstitution);
    }

    // Open document
    using var document = new Aspose.Pdf.Document(dataDir + "PDFToPDFA.pdf");

    // During the conversion, the missing font will be replaced with the substitution one
    document.Convert(dataDir + "ReplaceMissingFonts.xml", PdfFormat.PDF_A_1B, ConvertErrorAction.Delete);

    // Save output document
    document.Save(dataDir + "ReplaceMissingFonts_out.pdf");
}