Limits of image flattening
Flattening a page to a JPEG and placing that image in a new PDF destroys the original text layer, comments, form fields, attachments and most metadata, because those objects are not copied. That is useful, and it is also a loss: people can no longer copy a paragraph you did not redact, and the file is usually larger.
Image flattening is not a complete intelligence-grade sanitiser. A very high-contrast mark on a busy background is obvious, but if you miss a running header, a thumbnail, or a second copy of a name in a footer, it will still be visible in the image — and if it is visible, it is there. The tool does not yet OCR scanned pages to find words for you, and it does not open password-locked files. Scanned pages can still be redacted: you are painting over the pixels.
Checked 12 November 2026. This is a utility, not legal advice.