Understanding Color Management

Every day people encounter printed color materials that attempt to gain their attention and communicate an idea both with text and color images. As there are more channels available to reach people, graphic content creators have more choices of where to place their content and their dollars. The cost of printing has been democratized and four-color process printing is available to everyone. In addition, the Internet is another distribution channel, where color is virtually free. The expectation in terms of color quality has been raised. Ensuring that color is managed and reproduced correctly requires having the knowledge and the tools to be able to do so.

Four-color process reproduction has been available for some time now in the digital print environment. Every major equipment manufacturer has a line of four-color process digital print engines in their portfolio, and costs are decreasing. With the proliferation of digital color engines, the expectations of digital color quality have changed too. Not only do we require halftone images and vector art to vie for attention, now we’re expected to have control over the color, and hence the message that is communicated.

Color was a wow factor for digital printing, initially. In fact, studies have illustrated the ability to elicit a greater response rate and build brand recognition by utilizing color. By the same token, the incorrect reproduction of color can have dire consequences. Produce color incorrectly, and the print buyer will demand a refund or a reprint, not to mention the damage to your reputation. So how do we ensure that our color message is accurately reproduced? The answer lies with ICC color management. This technology has been available for the past 10 years and is now considered mainstream.

Though the technology has matured, there are still obstacles to achieving an excellent color match. These obstacles, or print variables, include differences in inks, toners, dot gain, hue error, tone reproduction, and color space to name a few. But don’t despair; with color management we can produce images and graphics that will match the original intent remarkably well.

Why Not a Perfect Match?

In a word: Color space. Color space has a significant impact on why a printed piece does not match the original image viewed on a monitor. Images on a monitor, for the most part, will be in the RGB (red, green, blue) color space. To produce images with this color space, different proportions of light are added together to produce a visual sensation. This is known as additive color theory.

When placing ink or toner on a paper, the subtractive color space is employed. Each of the CMYK colors is responsible for filtering one of the red, green, or blue wavelengths of light and reflecting the remaining two wavelengths of light to our eyes.

In order to better explain this concept, please see the chart below:

When we work with color, we are working with two distinct color spaces. In addition, the two color spaces vary in size. The RGB color space is significantly larger than that of its CMYK counterpart. The RGB color space can reproduce millions of colors, whereas the CMYK color space can produce a few thousand colors—paltry by comparison.

Having been involved with color management in the quick print industry, I have found the concept of color space to be very misunderstood, leading to incorrect color reproductions, incorrect expectations, and lastly, insurmountable anger from clients as to why the color was not produced correctly.

By having the knowledge that color is reproduced according to the size of the color space, it will help those of us who work with color to be able to produce it accurately. Another benefit is being able to take this esoteric information and explain it in a manner that is understandable to our clients.

It’s important to take a step back and understand that the vast majority of people who purchase four-color process printing don’t understand the technology. By explaining this concept of color space, you can prevent tempers from flaring and create a better working relationship.

What Does Color Management Do?

The concept of color management is to reproduce images and graphics in the most pleasing manner. Even though the process of color reproduction is constricted by the size of a color space, we can still produce color as faithfully to the original as possible.

One responsibility of a color management system is to compress the RGB color space to match the CMYK color space of the intended print engine. This compression occurs when we take an ICC profile and apply it to an image.

For demonstration purposes of this concept, I will use the Canon logo. I will take both an ICC profile created for a coated bright white paper, as well as a press profile created for an uncoated paper. There will be a shift in color, because the logo color is known as being “out of gamut” for these two ICC profiles.

The Canon logo below is a raw RGB image. It has not been converted to the CMYK components of each ICC press profile.

An uncoated paper will not be able to print this color as it originally appears because the color lies outside of the parameters of the CMYK color space. One of the reasons why the uncoated paper will not be able match the original intent is due to the fact that the uncoated paper reflects less light than a coated paper.

A coated bright white paper has the ability to reflect more light than an uncoated paper. All of the characteristics of the print process are captured in each profile. When the RGB Canon logo is converted to the CMYK values of each press profile, the color is converted to the closest reproducible color that can be achieved.

The white point of the paper will affect how the logo color will reproduce. The whiter the paper, the more light can be reflected, which produces a larger color space. Color management takes these factors into consideration.

This information about the uncoated paper is stored inside the ICC profile. When an RGB image or graphic has the profile applied, the RGB values are converted into the CMYK equivalents that will reproduce on press.

The Canon logo after an uncoated paper profile has been applied.

Uncoated press profile applied

You can see that the color has shifted to that of the color space of the press profile.

Next, the bright white coated paper profile is applied to the Canon logo:

The Canon logo after a brightwhite coated paper press profile has been applied.

The bright white coated paper has a much larger color space than an uncoated paper. Visually, we can discern the bright white coated paper reproduction is a more accurate representation of the original RGB logo.

You can see there is very little color difference between the original RGB logo and the logo after the conversion has been performed because the paper produces a larger color space and can more accurately match the original logo color.

It’s imperative to understand that color management will not take an RGB image and reproduce it identically on two different print engines. Even two print engines, manufactured by the same vendor will have some variation from one press to the next.

This concept is known as device independent color. Each device produces CMYK values differently. You may wonder then, how is it possible to produce the same color on each press, despite the differences in CMYK values?

This is a good question. An ICC color management system understands the idiosyncrasies of each press. The ICC profile will adjust the CMYK values in order to produce the correct color, in this instance the Canon logo. If the logo were to print on two different digital color presses, the colors would be substantially similar.

The ICC profile will know how to modify the CMYK dot areas on each press. So, even though the dot areas will be different for each device, the color will be very similar, which is the ideal condition we are looking to create.

In conclusion, color management is a diverse topic that includes a myriad of different systems that work in cohesion together. It is hoped that the information provided in this article will demystify some common misconceptions about color space and producing color on different print processes and equipment.

Eric Olesh is a Technical Marketing Analyst for Canon U.S.A. Inc. His credentials include a Bachelor of Science in printing management and sciences from the Rochester Institute of Technology. He has experience in color management, quick printing, newspaper production, and marketing.