PDF compression works by optimizing three main components: images, fonts, and document structure. Images typically account for 80-95% of total file size, making image recompression the most effective optimization strategy.
Our compression engine offers three quality presets. The screen quality preset targets 72 DPI and achieves the smallest file sizes, ideal for documents viewed only on screen. The print quality preset maintains 150 DPI, suitable for most office printing needs.
Font subsetting removes unused glyphs from embedded fonts. A typical document uses only 40-80 characters from each font, so subsetting can reduce font data by 90% or more. The tool also consolidates duplicate font instances that sometimes appear in merged PDFs.
Structural optimization removes redundant objects, linearizes the file for faster web viewing, and compresses content streams using modern deflate algorithms. These optimizations alone can reduce file size by 15-25% even without touching images.