How to Compress PDFs in C# using IronPDF

How Do I Compress Images in PDFs?

JPEG compression quality ranges from 1% (very low quality) to 100% (minimal loss). Understanding these levels helps when working with PDFs containing embedded images or when you need to manage fonts and graphics.

• 90% and above: high quality
• 80%-90%: medium quality
• 70%-80%: low quality

Experiment with various values to balance quality and file size. Quality reduction varies based on input image type—some images show more noticeable clarity loss than others. This is particularly important when working with images from Azure Blob Storage or creating PDFs with custom watermarks.

:path=/static-assets/pdf/content-code-examples/how-to/pdf-compression-image.cs

using IronPdf;

ChromePdfRenderer renderer = new ChromePdfRenderer();

PdfDocument pdf = renderer.RenderUrlAsPdf("https://en.wikipedia.org/wiki/Main_Page");

// Compress images in the PDF
pdf.CompressAndSaveAs("compressed.pdf", 40);

What Results Can I Expect from Image Compression?

Reduced by 39.24%!

How Do I Compress PDF Tree Structure?

This feature reduces PDF size by stripping the tree structure created by the Chrome Engine. Pass removeStructureTree: true as the third parameter of CompressAndSaveAs to enable it. It's most effective with Chrome Engine-generated PDFs containing extensive table data. Some rendering engines output PDFs without this structure, making the feature ineffective in those cases. This technique is valuable when working with complex layouts or merging multiple PDFs with redundant structural elements.

Removing tree structure may affect text highlighting and extraction effectiveness. Consider this trade-off when applying compression, especially if users need to extract text and images from compressed PDFs.

Test CompressAndSaveAs with tree structure removal using this PDF with table data.

:path=/static-assets/pdf/content-code-examples/how-to/pdf-compression-tree-structure.cs

using IronPdf;

PdfDocument pdf = PdfDocument.FromFile("table.pdf");

// Compress tree structure in PDF
pdf.CompressAndSaveAs("compressedTable.pdf", null, true);

What File Size Reduction Can Tree Structure Compression Achieve?

Reduced by 67.90%! This percentage increases with larger table PDFs.

How Can I Apply Both Compression Methods Together?

CompressAndSaveAs handles both image and tree structure compression in a single call — pass a quality value and set removeStructureTree to true. This combined approach is particularly effective for complex PDFs containing images and structured data, such as reports with charts or documents with embedded tables and graphics.

:path=/static-assets/pdf/content-code-examples/how-to/pdf-compression-compress.cs

using IronPdf;

PdfDocument pdf = PdfDocument.FromFile("sample.pdf");

// Configure compression with automatic optimization
pdf.CompressAndSaveAs("compressed.pdf", 80, true);