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Home » Newsletter » August 2007

By Raju Sinha

Last month, we saw how PDFOne .NET optimized PDF document size on its own. This month, we will see how you can further optimize PDF file size by using some advanced functions provided by PDFOne .NET.

If your PDF files contain a lot of monochrome images, say scanned copies of paper documents, then you could store the images in CCITT3 format rather than in BMP or JPEG.

CCITT3 image compression format is optimized for monochrome images. File size of PDF documents with CCITT3 images are a lot less than that of documents with BMP or JPEG images.

To illustrate this, I used a black and white (B&W) image test.jpg (shown below) and created two PDF documents.

The first document was created without any specified compression for the B&W image. (The image was already compressed JPEG.) For the second document, CCITT3 compression was explicitly specified.

Dim doc1 As New PDFDocument
doc1.DrawImage("c:\test.jpg", 1, 1) 
doc1.OpenAfterCreate = True
doc1.Save("c:\jpeg_image_compression_doc.pdf")
doc1.Close()

Dim doc2 As New PDFDocument
doc2.DrawImage("c:\test.jpg", 1, 1, _
               PDFImageCompressionFormat.CCITT3) 
doc2.OpenAfterCreate = True
doc2.Save("c:\ccitt3_image_compression_doc.pdf")
doc2.Close()

The image test.jpg was 29 KB and so the first document was 31 KB. With CCITT3 compression, the PDF file became 7 KB - nearly 75% reduction in file size!

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Downloads:

• test.jpg
• jpeg_image_compression_doc.pdf
• ccitt3_image_compression_doc.pdf