Addon

How can I generate PDF/A files?

Dynamic Web TWAIN supports exporting documents as PDF/A starting from version 19.3. PDF/A is an archival format designed for long-term preservation. The following variants are supported:

Supported PDF/A Versions

What’s the difference between PDF/A-1b and PDF/A-2b?

Although both variants ensure that documents can be reliably displayed in the future, they differ in terms of supported PDF features and compression options.

• PDF/A-1b
  • Uses the older PDF 1.4 specification.
  • Does not support JPEG2000 or JBIG2 image compression.
  • Does not allow transparency.
  • May result in larger file sizes and more conversion restrictions.
• PDF/A-2b
  • Based on newer PDF versions (1.5–1.7).
  • Supports JPEG2000, JBIG2, transparency, and other modern PDF features.
  • Typically requires fewer changes to the source document.
  • Usually produces smaller output files.

Recommendation: For most use cases, we recommend using pdf/a-2b. It offers better compression support, fewer limitations, and higher compatibility with modern PDFs while still meeting archival requirements.

Licensing Requirements

Dynamic Web TWAIN does not require any add-on license to export or generate PDF or PDF/A files. However, PDF Rasterizer add-on would be required when loading a PDF/PDF-A file that contains text or vector graphics.

You can programmatically check whether a file needs rasterization using IsRasterizationRequired():

DWTObject.Addon.PDF.IsRasterizationRequired(path); // returns true or false

Behavior and Defaults

• If you do not set pdfaVersion, the export uses standard PDF format (non-PDF/A).

• If you set pdfaVersion but forget to set version, or set a mismatched or incorrect PDF version, Dynamic Web TWAIN automatically falls back to a default PDF version:

  • pdf/a-1b → defaults to PDF 1.4
  • pdf/a-2b → defaults to PDF 1.5

How to Export as PDF/A

Configure PDF output using Write.Setup() before calling any save function.

DWTObject.Addon.PDF.Write.Setup({
    version: "1.5",          // [optional] 1.4 for "pdf/a-1b"; 1.5/1.6/1.7 for "pdf/a-2b"
    pdfaVersion: "pdf/a-2b"  // "pdf/a-1b" or "pdf/a-2b"
});

After configuring pdfaVersion, all APIs that output PDF files will automatically generate PDF/A-compliant PDFs. This includes, but is not limited to:

• Save APIs like: SaveAsPDF(), SaveSelectedImagesAsMultiPagePDF(), SaveAllAsPDF()

• Conversion APIs like: ConvertToBlob(), ConvertToBase64()

• Upload APIs like: HTTPUpload(), FTPUpload(), httpUploadBlob()

• OCR Output APIs like: SaveToPath(), SaveAsBase64(), SaveAsBlob()

Original post creation date: Nov 30, 2021

Last modified date: Dec 10, 2025