optimization
How PDF Compression Actually Works: Lossless vs Lossy Optimization
A technical breakdown of raster image subsampling, vector preservation, font subsetting, and internal PDF object stream compression.
Key takeaways
- Text and vector paths are compressed losslessly using Flate/Deflate algorithms with zero degradation.
- Embedded JPEG and PNG photographs are optimized through resolution subsampling and quantization.
- Unused embedded fonts and redundant metadata streams are safely stripped to maximize size reduction.
The Three Main Components of a PDF File Size
Large PDF files are rarely caused by plain text. A 100-page novel of pure text usually takes less than 1 MB. High file sizes typically stem from three elements: high-DPI scanned photos (often 300 to 600 DPI from office copiers), uncompressed embedded raster graphics, and redundant font subsets.
MakePDFRight’s compression engine targets these bloated components while leaving core vector structures completely untouched.
Balancing File Size vs Visual Quality
When you select Recommended Compression, the system downsamples 300+ DPI images to screen-friendly 144–150 DPI, which reduces the file size by 60%–80% without noticeable pixelation on laptop screens and mobile phones.
For strict job portals or government email attachment limits (e.g., under 2MB), Extreme Compression applies deeper DCT quantization, making the file ultra-lightweight while keeping text crisp and fully readable.