A digital signature in a PDF protects the exact bytes of the signed range. Compressing, merging, splitting or rotating pages all rewrite the file, and the signature then reports “modified”.
What to do#
- Compress the scan first and sign it last.
- If you only need a copy for viewing or archiving, you can create a “compressed copy (signature removed)”. It carries a note on every page and doesn’t replace the original.
- If you must submit the signed version, keep the original file unchanged.
Your signed original always stays untouched on your device; PinchPDF never modifies the original file.