Canon PIXMA MG4200 Series On-Screen Manual page 606

Grayscale Printing
Set grayscale printing. Grayscale printing refers to the function of converting your document to grayscale
data in the printer to print it in monochrome.
When you check the check box, both monochrome and color documents will be printed in monochrome.
When printing a color document, be sure to uncheck the check box.
Related Features
Setting the Print Quality Level (Custom)
Printing a Color Document in Monochrome
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