CMYK & RGB – the difference

RGB is the world of screens: red, green and blue light up and mix into color. CMYK is the world of print: cyan, magenta, yellow and black (K for “key”) are laid down on paper as tiny dots. Because printed colors don't glow, bright screen colors – especially vivid blue or neon – usually look a bit more muted in print. Most online printers convert RGB to CMYK automatically; if you want control over the result, convert it yourself with a proper print profile.

PreflightPilot finds RGB images, shapes and text in your PDF and converts them to CMYK using a real print profile (GRACoL 2013 for US sizes, FOGRA51 for ISO sizes). Gray and black become pure black (K), so small text stays crisp.