How to Compress a PDF Without Losing Visual Quality | Qeviro Guide

Vector Text vs. Raster Images: The Crucial Difference

In a properly structured PDF generated from software like Microsoft Word, Google Docs, Figma, or InDesign, characters are not stored as pixels. They are stored as mathematical Bézier curves called vector glyphs.

When low-quality compressors shrink a PDF, they take the crude shortcut of flattening every page into a low-resolution JPEG picture. This destroys text searchability, selectable text, and causes character blurring on high-resolution displays.

The 3 Techniques for High-Quality PDF Compression

1. Object Stream Packing (Lossless)

Older PDF formats store internal object dictionaries in loose, uncompressed ASCII streams. Modern Flate/Deflate re-encoding compresses these structural descriptors without altering a single pixel or font glyph.

2. Unused Resource & Revision Stripping

When a PDF is edited multiple times, previous revisions and unused font subsets often linger inside the container. Scrubbing unreferenced binary nodes drops megabytes of bloat losslessly.

3. Perceptual Image Downsampling

For documents with embedded scans, 300+ DPI images are downsampled to a calibrated 150 DPI. This cuts image weight by over 60% while matching the exact pixel density of retina smartphone and laptop displays.

Recommended Compression Settings in Qeviro

Legal Contracts & Research: Select Low Compression to preserve 100% vector fidelity and full-resolution graphics.
Marketing Reports & Portfolios: Select Balanced Compression for optimal 50%–70% size reduction with sharp screen viewing.
Fast Emailing: Select Maximum Compression if your file must squeeze under a strict 5MB or 10MB limit.

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