Two ways to remove color
Keep text changes the colors inside the PDF. Text colors, lines, shapes, fills, simple gradients and palettes are rewritten as shades of gray using the usual brightness formula, and every color image is converted to gray. The text stays real text: you can still select, search and copy it, and it prints sharp at any size.
Some content cannot be converted this way, for example special print inks, complex gradients or images stored as JPEG 2000 or CMYK JPEG. After converting, the tool draws every page and looks for colored pixels. If it finds any, the row tells you which pages, so you are never surprised at the printer.
Pages as images: always gray
Pages as images draws each page at 100, 150 or 300 DPI and stores it as a gray image. The result has no color at all, guaranteed, but text can no longer be selected. Black and white turns every pixel either black or white, which suits scanned letters and forms and keeps files small. Choose 300 DPI for small print.
Why print in grayscale
Printing in gray saves expensive color toner, and many offices print color pages at a higher price. Some job portals, courts and archives ask for black and white documents. Gray copies also make it easy to check that charts still read well without color.