Why Don't Printed Colors Match What I See on the Monitor?

Printers don't print colors they way they look on a monitor. The picture may look great on the monitor but doesn't print true to the screen. These colors will never be a perfect match because the image on the screen and the image from the printer use two different color sources. The screen pixels are emitted light and a printer can't print light. It uses dyes and pigments to replicate the colors.

How RGB and CMYK Differ

A computer monitor is composed of pixels and each pixel displays over 16 million colors. The actual number is 16,77,7216 which is 2 to the 24th power. These colors are in the RGB gamut which is composed of all the colors in light.

A printer only reproduces a few thousand colors due to the principle of absorption and reflection. The pigments and dyes absorb the light colors that aren't used and reflect the CMYK combination that closely approximates the actual color. In all cases, the printed result is a bit darker than the screen image.

The bottom line is the number of colors available in a particular color space. Color printers such as inkjet printers have cyan, magenta, yellow, and black cartridges. These are the traditional printing inks and the color is made by combining these four colors. With ink, the number of colors that can be produced fall, roughly, into a maximum of a couple of thousand distinct colors.

You Can't Print Light, so Your Images Print Darker

If you draw a circle on a sheet of paper and put a black dot in the middle of that circle you will get a good idea of why colors change. The sheet of paper represents all of the colors visible and invisible — infrared, ultraviolet, x-rays. The circle represents the RGB gamut. If you draw another circle inside the RGB circle you have the CMYK gamut.

If you move from a corner of that sheet of paper to the dot, that indicates how color moves from invisible to a black hole which is the dot. As you move toward the dot, colors get darker. If you choose a red in the RGB color space and move it to the CMYK color space the red will darken.

RGB colors that are output as CMYK colors are pulled to the nearest CMYK equivalent which is always darker. The reason why the printer output doesn't match the screen is because light can't be printed.

Other Factors That Affect Printed Colors

If you are printing at home on a desktop printer, it's not necessary to convert photos and graphics to CMYK color mode before printing. All desktop printers handle this conversion. The explanation above is intended for 4-color process printing on a printing press.

Paper and ink selections can also have an impact on how true colors reproduce in print. Finding the perfect combination of printer settings, paper, and ink can take experimentation, but using the printer and ink suggested by the printer manufacturer often provides the best results.

Most graphics software have a setting for color management. If you let the software do the work, you will still get good results by turning color management off. Color management is primarily intended for a pre-press environment. Not everyone needs it. If you're not doing professional printing, first work without color management before you assume you need it.