Why PDFs are large
Most PDF size comes from embedded images, especially scans and photos, and from embedded fonts. Text and vector graphics are usually small. Removing or reducing images is therefore the main way to shrink a file.
Two methods in Pixuna
Re-save only rewrites the file with a more compact structure. It keeps text, links, and image quality, but often saves little because images and fonts are not recompressed.
Flatten pages to images renders each page as a JPEG and rebuilds the PDF from those pictures. This can shrink scans and photo-heavy files, but text stops being selectable and searchable, and links and form fields are lost.
Choosing and checking
Try Re-save only first. If the file is still too large and it is mostly scanned pages, use flattening and compare Smallest, Balanced, and Sharper quality.
If a setting would not make the file smaller, Pixuna returns the original unchanged and tells you. Results vary by file; no specific size is guaranteed.
- Keep the original file.
- Zoom into the result to check legibility, especially small print.
- Do not flatten documents that need searchable text or fillable fields.
Other ways to get under a size limit
Split the document into parts, extract only the pages you need, or compress the source images before building the PDF. The Images to PDF tool can combine images you have already resized.