Key factors in color perception

Every day, thousands of design files are sent around the world for the production of printed materials. Some of these files lead to results that closely match the expectations of the designer and the client, while others—despite significant time and expense—deliver an output different from what the designer had envisioned.

It has often happened that a design looks perfectly satisfactory on a monitor, but after printing, the colors take on a different appearance. Sometimes a printed sample is approved by the designer, yet from the client's perspective it requires revision. In other cases, several people look at one printed sample, but each has a different perception of its color.

In such situations, factors such as file settings, print quality, ink type, or production conditions are typically examined. But before addressing all these issues, we need to answer a more fundamental question: What is color, and why do we perceive it the way we do?

Many professionals in the printing industry directly associate color with concepts such as RGB, CMYK, or color profiles. Although these tools form an important part of the modern printing workflow, none of them explain the origin of how color is formed. To properly understand color management, printing standards, and achieving predictable results in production, we must first become familiar with more fundamental principles—principles upon which all color systems and color management processes are built.

Does color really exist in a design file? If so, why can a specific color be perceived differently under various conditions? Many challenges related to color management, print quality control, and accurate color reproduction are rooted in concepts that were formed long before RGB, CMYK, and color profiles.

1. Light Source

Before we discuss color, we must answer a simple question: Without light, is there any color to see?

Imagine you are in a completely dark room and a green t-shirt is placed on the chair in front of you. As long as no light shines on the surface of this t-shirt, it is practically impossible to distinguish its color. In such conditions, not only the green color, but no other color is visible either.

This example shows that color is not an independent and permanent attribute, but rather the result of the interaction of light with the surface of objects and ultimately the perception of the human eye. However, the presence of light alone is not enough. Suppose you observe the same green t-shirt once under natural daylight and once under a blue lamp. Would you have the same perception of color in both cases? Certainly the answer is no.

Each light source produces light differently, and this can alter how colors appear and are perceived. This is why a printed product may look different in various environments, even though the product itself has not changed.

In the printing industry, evaluating color without considering lighting conditions can lead to incorrect judgments. For this reason, international standards have defined specific conditions for color evaluation, and standard light sources are used in the printing industry to create uniform viewing conditions.

2. Observer

Imagine a printed sample is placed on a table. The ambient light is the same for everyone, and the sample has not changed. But one person approves the color while another believes it is still far from the target color. In such a situation, what causes this disagreement? The answer to this question leads us to the second effective factor in color perception: the observer.

After the light source, the second effective factor in color perception is the person who observes the color. Many of us assume that if two people look at a printed sample, both will see exactly the same color. But in practice, this does not always happen. The ability to distinguish colors can vary among individuals. Factors such as visual health, age, eye fatigue, visual adaptation to the environment, and even the presence of certain visual impairments can affect how color is perceived.

For example, someone who has been working with a monitor for hours may evaluate the same printed sample differently from someone who has just begun the observation. Also, individuals with some degree of color blindness may perceive certain colors differently from others. On the other hand, the human eye has a remarkable ability to adapt to environmental conditions. For this reason, after spending some time in an environment with specific lighting, the brain tries to interpret those conditions as normal. Although this feature is very useful in everyday life, it can lead to different interpretations in color evaluation.

For this reason, in the printing industry, color judgment should not be based solely on personal taste or individual perception. The more standardized and repeatable the viewing conditions are, the more likely it is to achieve a more accurate and reliable evaluation. Of course, creating a precise environment and defining exactly what the observer's viewing conditions are may not be simple, but in order to reach a common understanding of color, a definitive decision must be made.

3. Object

So far we have seen that lighting conditions and the observer can affect color perception. But if both the light and the observer are constant, could colors still appear differently? After examining the role of the light source and the observer, we now reach the third effective factor in the formation and perception of color: the object or surface with which light interacts. Many people assume that the color we observe is simply the color printed on the surface. But in reality, what our eyes detect is the light that is reflected back toward us after striking the surface of the object.

When light hits a surface, part of it is absorbed and part is reflected. The type of reflection and the amount of light absorption depend on the surface characteristics, and this is why two different materials—even when using the same color—can appear differently. To better understand this, suppose we print a specific corporate color on uncoated paper, glossy paper, kraft board, and a metallized material. Even though the color formula and printing values are identical across all samples, the final result will differ on each of these surfaces.

White and glossy papers typically reflect more light, making colors appear more vibrant and brilliant. In contrast, darker or colored surfaces such as kraft board absorb part of the light and can affect the final appearance of the color. Metallized materials, due to their reflective structure, behave differently from other surfaces and can significantly alter the visual effect of the color.

In addition to the material type, post-printing processes can also affect how light is reflected from the surface. For example, the use of matte lamination, glossy lamination, spot UV coating, or other finishing treatments can change the amount of light reflection and consequently alter the visual perception of color.

For this reason, in the printing and packaging industry, achieving a predictable result is not possible solely by controlling the design file or print settings. Understanding the material characteristics and its behavior in response to light also plays an important role in proper color management.

Conclusion

It was examined that the perception of color is not the result of a single factor, and three factors must be present simultaneously. If a printed sample is viewed under different lighting, observed by a person with different visual conditions, or produced on a material with different surface characteristics, the final perception of color can change—even if the design file has not been altered in any way.

A change in any of these factors can alter our perception of color. For this reason, color evaluation and control can only be reliable when all these factors are examined under specified and repeatable conditions. Understanding these three fundamental principles serves as a foundation for entering more advanced topics in color management, color spaces, color profiles, print process standardization, and production quality control.