TSUBAMI / PRACTICAL GUIDE
Cropping, covering and redacting a PDF are different
Know whether you are changing a page’s view or removing source content.
Updated October 24, 2026 · Tsubami
Cropping changes the view
Crop PDF adjusts the visible page box. It can trim margins or show only one area, but text and images outside the crop box may still be stored in the file. Do not use a crop as a way to remove confidential material before sharing.
An overlay can leave content underneath
Edit PDF can add text, images, outlines and highlights above existing page contents. Drawing a rectangle over a sentence does not necessarily delete the sentence or stop it from being extracted. A dark appearance is not evidence of permanent removal.
Area redaction rebuilds page pixels
Tsubami’s Redact PDF renders the pages, burns a black rectangle into the selected area on chosen pages, and embeds the resulting images in a fresh PDF. All source pages are rebuilt, including pages where no rectangle is applied. The copy discards source text layers, forms, attachments and source metadata.
The tradeoff is an image-only document
Rebuilt pages lose searchable text, links, interactive form fields and digital-signature behavior. The tool does not detect sensitive contents automatically and applies the rectangle to the selected page positions. It is not a certified redaction or compliance service.
Inspect every relevant page
Check that the correct pages and rectangle were selected. Open the output at full size and inspect adjacent text, repeated details, headers and footers. Consider all sensitive contents, rather than assuming the single visible area was the only place information appeared. Keep the original private, and use a suitable specialist workflow where formal guarantees are required.
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.