How PDF to Grayscale works
PDF Grayscale converts every page of a colour PDF into a grayscale document, useful for reducing print costs, meeting black-and-white submission requirements, or simply stripping colour information before archiving. The output is a standard PDF with each page rendered in shades of grey by pdf-lib.
This is different from compressing a PDF (which keeps colours but shrinks the file) or converting to images (which produces separate picture files). For those, see the PDF compress and PDF to images tools. The conversion re-renders page content, so a searchable text layer may not be fully preserved; run OCR on the output if you need selectable text.