How does PDF compression reduce file size without losing text sharpness?

Compression downsamples embedded high-DPI raster images to standard display resolutions (72–150 DPI), applies DCT/JPEG quantization, and strips unreferenced font dictionaries and metadata streams while leaving vector text mathematically untouched.

What is the difference between Low, Recommended, and Extreme PDF compression?

Low compression preserves high image detail (200+ DPI) for print proofs. Recommended achieves a 50–70% reduction with clean visual fidelity for everyday sharing. Extreme applies aggressive quantization for strict email limits.

Why is my scanned PDF file size so large and how do I shrink it?

Scanners often save full-color 300+ DPI uncompressed TIFF or PNG bitmaps per page. Compressing the PDF re-encodes these raster streams with optimized JPEG compression, reducing a 50MB file down to 2–5MB.

Does compressing a PDF remove bookmarks, hyperlinks, or fillable form fields?

Standard compression optimizes media streams without stripping interactive features, bookmarks, internal hyperlinks, or form field dictionaries.

What is the maximum file size reduction possible on a PDF?

Image-heavy documents and unoptimized scans can typically be reduced by 70% to 90%. Text-only vector documents with minimal images will see smaller reductions because vector fonts are already compact.

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