How do I embed thumbnails in PDF?

Q: How do I embed thumbnails in PDF?
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A: You can use PDFNet SDK (www.pdftron.com/pdfnet) to convert PDF
pages to images (or thumbnails) and these images can be embedded in
PDF.

For an example of how to render PDF pages, please take a look at
PDFDraw sample project (http://www.pdftron.com/pdfnet/
samplecode.html#PDFDraw).

Once you have a PDF thumbnail (pdfdraw.GetBitmap() ->
System.Drawing.Bitmap) you can embed it in the document with
pdftron.PDF.Image.Create() method.

To associate this PDF image with a page use the following line:

page.GetSDFObj().Put("Thumb", image.GetSDFObj());

Similarly you can call PDFDoc.GenerateThumbs(max_dimension) to embed thumbnails in all pages of the document:

https://www.pdftron.com/pdfnet/docs/PDFNet/html/M_pdftron_PDF_PDFDoc_GenerateThumbnails.htm