Two ways to make color
RGB and CMYK are color models. Each describes how to build a color from a small set of ingredients, and each matches a different kind of device.
RGB: additive color
Screens start dark and add light. Red, green and blue light sources are combined in different amounts. Full red, green and blue together make white. No light at all is black. Phones, monitors and televisions all work this way.
CMYK: subtractive color
Paper starts white and reflects light. Ink absorbs (subtracts) part of that light before it reaches your eye. Cyan, magenta and yellow inks each absorb a different range of the spectrum. Black (the K, often called key) is added because mixing the three colored inks does not give a deep, neutral black in practice, and because black text and fine detail are easier to print with a dedicated ink.
Why screens look brighter
A screen emits its own light, so its brightest white is a light source. Paper can only reflect the light in the room, so its brightest white is whatever your lamp or window provides, minus some loss. Ink then removes more light on top of that. The practical result is that very bright, saturated colors on a display, especially vivid blues, greens and neon tones, often cannot be matched by ink on paper.
Color range matters too. The set of colors a device can reproduce is called its gamut. A typical display and a typical inkjet have different gamuts that overlap but do not match. Some screen colors fall outside what the printer can make, and the printer has to substitute the nearest color it can reproduce.
Where conversion happens
Most documents and photos are created in RGB. Somewhere between your screen and the paper, that RGB data has to become ink amounts. This can happen in the application, in the operating system’s print system, in the printer driver, or inside the printer itself. Many home inkjets accept RGB and convert internally, so you may never see CMYK values directly.
Print shops and professional workflows often work in CMYK files from the start. That gives the designer direct control over ink amounts, but it is not required for ordinary home printing.
What color management does
Color management tries to keep colors consistent between devices. It uses profiles, which are small data files that describe how a particular device reproduces color. With a profile for your display and one for your printer and paper, software can convert colors in a way that makes the output look closer to what you saw.
- Applications such as photo editors can handle the conversion themselves, in which case the driver should be told not to adjust colors again.
- Or the printer driver can manage color, in which case the application should not also convert.
Doing both, or neither in the wrong place, is a common cause of colors that look off. Check your application’s print dialog and the driver’s color settings so that only one of them is in charge. The exact option names vary, so the printer manufacturer’s support pages are the best reference for your model.
Paper and ink also change the result
Glossy photo paper holds ink on the surface and generally gives richer color and deeper blacks than plain office paper, which absorbs ink. Selecting the wrong paper type in the driver can shift the color noticeably, because the driver adjusts ink amounts to suit the paper it believes is loaded.
How to see it on your own printer
Printing a test sheet is the easiest way to see how your printer handles color. The CMYK test page shows each ink on its own plus overlaps, so you can check that every channel prints. The color test page adds ramps and common tones, and the photo test page checks skin tones, gradients and gray balance. Our PDFs use DeviceCMYK values, which means the color values are specified in CMYK terms and do not depend on an embedded profile.
Compare the print to your screen in good daylight rather than under a colored bulb. Expect the print to look somewhat less luminous. That alone is normal. Look instead for a missing channel, strong tint across neutral grays, or banding. If grays lean toward a color, see wrong colors.
A short summary
- RGB adds light and suits screens. CMYK subtracts light and suits ink on paper.
- Screens usually look brighter because they emit light and have a different gamut.
- Color management uses profiles to keep results consistent, but only one stage should do the conversion.
- Paper type and driver settings change the result as much as the file does.