How to compress a scanned pdf using lossless compression
- Step 1Upload the scanned PDF — Drop the image-only PDF into the lossless compressor.
- Step 2Select the scan type — Choose black-and-white or colour scan optimisation for the best compression ratio.
- Step 3Compress losslessly — Apply JBIG2 or lossless JPEG 2000 compression to the scan pages.
- Step 4Download and verify — Compare the output against the original scan to confirm quality.
Frequently asked questions
How much smaller will a scanned PDF be after lossless compression?+
Black-and-white document scans can reduce by 50-80% with JBIG2. Colour scans typically see 20-40% reduction with lossless methods.
Is lossless compression suitable for scanned medical images?+
Yes — medical scan archives require lossless compression to preserve diagnostic image quality. JBIG2 and lossless JPEG 2000 are both used in clinical archiving.
Should I apply OCR before or after lossless compression?+
Apply OCR first to add the text layer, then compress. This ensures the OCR layer is included in the compressed document.
Privacy first
All PDF processing runs locally in your browser using PDF-lib and pdf.js. No file is ever uploaded — only metadata counters are saved for signed-in dashboard stats.