Convert colorful PDF to grayscale PDF by using A-PDF to BlackWhite

From: http://a-pdf.com/faq/how-to-convert-a-color-pdf-to-grayscale-pdf-by-using-a-pdf-to-black-white.htm. Tell you the step-by-step tutorial about how to convert a color PDF to grayscale PDF by using A-PDF to Black/White. Learn more: http://a-pdf.com/bw/index.htm