TSUBAMI / PRACTICAL GUIDE
Compress a PDF without losing text—or flatten it?
Two different ways to reduce PDF size, with different tradeoffs.
Updated October 24, 2026 · Tsubami
Try structural optimization first
Optimize PDF rewrites the file structure and recompresses streams without intentionally converting page text or vectors to images. It does not lower image resolution. It can reduce structural overhead, but an already efficient document may stay the same size or become larger.
Image-only compression changes the document
Compress PDF renders pages into images and creates a fresh image-only PDF. Resolution controls the number of pixels; JPEG quality controls image compression. This can help with large scanned documents, but it removes searchable text, interactive forms, links and signature behavior.
Compare actual output sizes
Neither method guarantees a saving. The result displays the generated size and whether it is smaller than the source. A document containing mostly efficient text and vector graphics may become much larger if converted into page images. Keep the output only if it meets your requirements.
Check readability at full size
Lower resolution and quality can make small lettering, fine lines and scans harder to read. Open the processed copy and inspect representative dense pages, not only the first page. If a file-size limit is strict, consider removing unnecessary pages or splitting a document when the receiving service permits it.
Keep important originals
Rewriting or editing a PDF can invalidate signatures and alter interactive features even when its page appearance looks unchanged. Preserve original documents. Structural repair is a separate best-effort operation and cannot recreate missing document contents.
Tools for this job
These guides describe the current Tsubami tools and their limitations. Keep originals and inspect outputs before relying on them. See supported files and limits.