A smaller PDF without an unpleasant surprise
When to use lossless optimization, when scans benefit from image compression, and what to check.
First, work out what makes the file large
A PDF with high-resolution scanned images behaves differently from a PDF containing text and vector graphics. Scans often benefit from image compression. An already optimized text document may barely shrink, and re-encoding it can make it larger.
Try lossless optimization first
PaperLumo’s lossless mode rewrites PDF object streams. It preserves selectable text and does not rasterize the pages. This is a sensible first step for reports, invoices and text documents. If the new file is not smaller, the tool returns your original file unchanged.
Use image mode carefully
Image compression renders pages and stores them as JPEG images in a new PDF. Lower quality usually reduces file size, but small text and fine lines can become less clear. Text will no longer be selectable, and links and form fields will not remain interactive. Avoid this mode for accessibility-sensitive documents.
Do not promise an exact target size
Different documents compress differently. There is no guaranteed percentage reduction or exact 100 KB target. Check the actual output size and inspect several pages at normal reading size, particularly pages with small type or diagrams. If a portal rejects the file, split unnecessary pages out before reducing quality further.