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Understanding Colors: HayLoise's Branding Tips

Have you ever found yourself wondering:

• why don�t colors match between my computer and what prints on my inkjet printer?
• why does a digital picture look great on my screen and come out fuzzy or ragged wen I print it?
• why does a commercial printer tell me they can�t print a file I sent them?
• what are all those different file formats? when do I use one versus another?
• what is the right program to use to create various types of documents or images?

We have some answers for you. Not all of them. But the basics.

Color Gamut

This diagram, known as CIE 1931 chromaticity diagram, represents all the colors visible to the human eye.

The most important thing to know about color generated from your computer is:

• Input devices (scanners, digital cameras) do not have the ability to "see" all the colors that the human eye can perceive.
• Output devices (monitors, printers, video recorders) cannot reproduce them all.

Furthermore, each device has it�s own particular gamut of colors which differs from every other.

For example, monitors from the same manufacturer with the same model number will have different color gamuts. Printers from the same manufacturer will produce different gamuts depending on the particular inks that are used, the type of paper printed used, as well as the printer settings.

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Monitors use RGB colors

The RGB color space, used by televisions and computer monitors, is made up of three luminous, or glowing, colors. The RGB color space is represent by the triangle superimposed on the CIE diagram. The colors that lie within that triangle can be reproduced by an RGB monitor.

RGB Color space is a LUMINOUS or ADDITIVE system of Red, Green, and Blue Light. When these colored lights are either projected on top of each other, or lit up next to each other, in different intensities, we can see millions of different colors (or thousands, depending on the settings on your monitor).

Black is displayed on a monitor by REMOVING all three sources of color. White is displayed by ADDING maximum amounts of all three colors.

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Printer use CMYK colors

The CMYK color space, used in the printing process, is made up of Cyan, Magenta, Yellow as primary colors and Black ink to achieve a true black. It is known as �process� color. The CMY color space is represent by the dashed circular shape superimposed on the CIE diagram. The colors that lie within that circle can be reproduced by in a CMY(K) printing process.

CMYK Printing is a REFLECTIVE or SUBTRACTIVE system. The inks filter light as it is reflected off the paper, allowing only certain wavelengths of light to reach your eyes. By adjusting the amount of any ink on the paper, the reflected wavelength changes, changing the color you see. When screens of the four colors are combined in a proper pattern on paper, the human eye merges them into one color.

On a white piece of paper, black is displayed by ADDING color inks (dotwise) and white by REMOVING, or not printing it.

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The problem with printing what you see on the screen

The RGB gamut of a monitor and the CMYK gamut of a printer do not overlap completely. As shown in the CIE diagram, they overlap and intersect with one another, but neither one completely overlaps the other.

The RGB color space is capable of producing many more colors than the process (CMYK) color space and many RGB colors you make on the computer simply cannot be reproduced on the press with �process colors� (CMYK). Bear this in mind when choosing colors for your designs... It may look good on your screen, but if you don�t choose colors that lie in the region where the palettes overlap, you will have to make adjustments between what you print, and what you display.

This means that there are some colors which can be seen on a particular monitor but which cannot be printed. The same is true in reverse. Colors capable of being printed, using CYMK inks, can not all be viewed on the monitor. Also, because of the fundamental variations in devices -- display, scanner, printer -- there are colors which can be seen on one monitor but not on another, or which can be picked up by a particular scanner, but cannot be printed on a particular printer... and so on.

Defining colors in RGB is totally incompatible with any printing press using CMYK. To get the best printed representation of an RGB color is must be converted into CYMK coordinates. Most design programs have the capability to do this.

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