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VB.NET PDF - How to Compress PDF in VB.NET


VB.NET PDF Document Compression and Decompression Control SDK




A standalone VB.NET PDF document compressing SDK that can perform PDF compression without any Adobe product


A high PDF compressing ratio control, built on .NET Framework 2.0


Support .NET WinForms, ASP.NET MVC in IIS, ASP.NET Ajax, Azure cloud service, DNN (DotNetNuke), SharePoint


Support large 1000 + page PDF document compression in VB.NET WinForms application


Compress & decompress PDF document file while maintaining original content of target PDF document file


Remove bookmarks, annotations, watermark, page labels and article threads from PDF while compressing


Also a preview component enables compressing and decompressing in preview in ASP.NET class


Also able to uncompress PDF file in VB.NET programs


Support PDF encryption in VB.NET class applications


A professional PDF compression and decompression library, which compatible with Windows 32-bit or 64-bit operating system


Offer flexible and royalty-free developing library license for VB.NET programmers to compress PDF file





VB.NET PDF Document Optimization



PDF document optimization is mainly to reduce or minimize original PDF document size, mainly methods are given below:



Reduce image resources: Since images are usually or large size, images size reducing can help to reduce PDF file size effectively. The disadvantage is that image resources pixel point might be lost.


Reduce font resources: Font resources will also take up too much space, glyph file unreferenced can be deleted. But it's too complicated to implement this work.


Delete unimportant contents:


  Flatten form fields


  JavaScript actions


  Alternate images


  Embedded page thumbnails


  Document tags


  Embedded print settings


  Embedded search index


  Bookmarks


  Comments, forms and multimedia


  Document and metadata


  All object data


  File attachment


  External cross references


  Private data of other applications


  Hidden layer content


  Convert smooth lines to curves


  Detect and merge image fragments


  Flatten visible layers




VB.NET Demo Code to Optimize An Exist PDF File in Visual C#.NET Project



Sample Code list below is mainly to optimize PDF file with multiple ways in VB.NET Class.




String inputFilePath = Program.RootPath + "\\" + "3.pdf";
String outputFilePath = Program.RootPath + "\\" + "3_optimized.pdf";

'create optimizing options
Dim ops As PDFOptimizeOptions = New PDFOptimizeOptions()

'--Options for Monochrome Image
'to enable dowmsampling for those images with resolution higher than 300 dpi to 150 dpi
ops.MonochromeImageOptions.DownsampleMode = ImageDownsampleMode.Bicubic
ops.MonochromeImageOptions.MaxResolutionLimit = 300.0F
ops.MonochromeImageOptions.TargetResolution = 150.0F
'to change image compression mode to JBIG2
ops.MonochromeImageOptions.KeepCompressionMode = False
ops.MonochromeImageOptions.Compression = PDFCompression.JBIG2Decode

'--Options for Grayscale Image--
'to enable downsampling for those images with resolution higher than 120 dip to 96dpi
ops.GrayscaleImageOptions.DownsampleMode = ImageDownsampleMode.Bilinear
ops.GrayscaleImageOptions.MaxResolutionLimit = 120.0F
ops.GrayscaleImageOptions.TargetResolution = 96.0F
'to change image compression mode to DCT
ops.GrayscaleImageOptions.KeepCompressionMode = False
ops.GrayscaleImageOptions.Compression = PDFCompression.DCTDecode
'set quality level, only available for compression mode DCT
ops.GrayscaleImageOptions.JPEGImageQualityLevel = JPEGImageQualityLevel.High

'--Options for Color Image
'to enable downsampling for those images with resolution higher than 120 dpi to 96dpi
ops.ColorImageOptions.DownsampleMode = ImageDownsampleMode.Bicubic
ops.ColorImageOptions.MaxResolutionLimit = 120.0F
ops.ColorImageOptions.TargetResolution = 96.0F
'to change image compression mode to DCT
ops.ColorImageOptions.KeepCompressionMode = False
ops.ColorImageOptions.Compression = PDFCompression.DCTDecode
'set quality level, only available for compression mode DCT
ops.ColorImageOptions.JPEGImageQualityLevel = JPEGImageQualityLevel.Highest

'apply optimizing
PDFOptimizer.Optimize(inputFilePath, outputFilePath, ops)