Spire.PDF allows us to compress PDF document in the following two ways:
- Compressing content
- Compressing image
Compressing content
In Spire.PDF, we can control the compression level of the document by using the PdfCompressionLevel enum. The compression level can be set to best, normal, above normal, none etc.
[C#]
//Loads the PDF document
PdfDocument doc = new PdfDocument("Test.pdf");
//Disables the incremental update
doc.FileInfo.IncrementalUpdate = false;
//Sets the compression level to best
doc.CompressionLevel = PdfCompressionLevel.Best;
//Saves and closes the resultant document
doc.SaveToFile("Compressed.pdf");
doc.Close();
[VB.NET]
'Loads the PDF document
Dim doc As New PdfDocument("Test.pdf")
'Disables the incremental update
doc.FileInfo.IncrementalUpdate = False
'Sets the compression level to best
doc.CompressionLevel = PdfCompressionLevel.Best
'Saves and closes the resultant document
doc.SaveToFile("Compressed.pdf")
doc.Close()
Screenshot:
Compressing image
We can compress/change the quality of the images in the PDF document by using the following code example.
[C#]
//Loads the PDF document
PdfDocument doc = new PdfDocument("Image.pdf");
//Disables the incremental update
doc.FileInfo.IncrementalUpdate = false;
//Traverses all pages
foreach (PdfPageBase page in doc.Pages)
{
//Extracts images from page
Image[] images = page.ExtractImages();
if (images != null && images.Length > 0)
{
//Traverses all images
for (int j = 0; j < images.Length; j++)
{
Image image = images[j];
PdfBitmap bp = new PdfBitmap(image);
//Reduces the quality of the image
bp.Quality = 20;
//Replaces the old image in the document with the compressed image
page.ReplaceImage(j, bp);
}
}
}
//Saves and closes the resultant document
doc.SaveToFile("Output.pdf");
doc.Close();
[VB.NET]
'Loads the PDF document
Dim doc As New PdfDocument("Image.pdf")
'Disables the incremental update
doc.FileInfo.IncrementalUpdate = False
'Traverses all pages
For Each page As PdfPageBase In doc.Pages
'Extracts images from page
Dim images As Image() = page.ExtractImages()
If images IsNot Nothing AndAlso images.Length > 0 Then
'Traverses all images
For j As Integer = 0 To images.Length - 1
Dim image As Image = images(j)
Dim bp As New PdfBitmap(image)
'Reduces the quality of the image
bp.Quality = 20
'Replaces the old image in the document with the compressed image
page.ReplaceImage(j, bp)
Next
End If
Next
'Saves and closes the resultant document
doc.SaveToFile("Output.pdf")
doc.Close()
Screenshot:
