Understanding Color and Vision in the Visual Spectrum: Why Red and Green Are Preferred Over Blue

When it comes to the visual spectrum, most modern devices like phones, tablets, computers, and TVs primarily use red, green, and blue (RGB) to create colors. However, in the realm of vision tests, and particularly in color blindness diagnoses, red and green are predominantly used, often leaving out blue. This article explains why the visual tests favor red and green over blue, and delves into the technical aspects of color theory and color mixing.

Color Blindness and Safety Concerns

Eye Tests and Color Vision: Vision tests are essential for identifying many visual issues, including color blindness. The most common form of color blindness involves difficulty distinguishing between red and green, conditions known as protanopia and deuteranopia. These conditions affect more people than blue-yellow color blindness, which is less common. Therefore, red and green are used in tests to detect these issues early and ensure safety in certain occupations or daily activities.

Occupational Safety: Jobs that require visual discrimination, such as hunting, flying, and navigating, rely heavily on perceiving colors accurately. Red and green traffic lights and warning signs are ubiquitous. Similarly, hunters' jackets are often red, which further emphasizes the importance of testing for red-green color blindness. On the other hand, blue and yellow deficiencies are less critical, leading to less emphasis on these colors in vision tests.

The Visible Spectrum and Color Mixing

RGB vs. CMYK: The visible spectrum itself does not fundamentally use red, green, and blue (RGB) for color representation. Instead, these are primary colors for devices that emit light. Devices like monitors, TVs, and mobile screens use additive color mixing, where light of these three primary colors is combined to produce other colors. This system gives a wide color gamut but is not the only method used in color theory.

Subtractive Color Mixing: In subtractive color mixing, which is used in reflecting materials like paints and dyes, the optimal primaries are cyan, magenta, and yellow (CMY). This method works by absorbing specific wavelengths of light and reflecting the rest. For example, cyan absorbs red light, magenta absorbs green, and yellow absorbs blue. These primaries complement the RGB system in certain applications, although they are not used as widely in modern device screens.

Printing and CMYK: In the printing industry, cyan, magenta, yellow, and black (CMYK) are commonly used. The addition of black helps improve the representation of dark colors and reduces the amount of ink needed for lighter shades. High-end printers might use even more primaries to achieve a larger color gamut. However, in basic household printers, the CMYK system is often used due to cost and practicality.

Technical Insights and Applications

RGB Usage in Additive Devices: While RGB is a widely used additive color system, it is not the only one. Kinemacolor, one of the first commercial color motion picture processes, used only red and green. This approach was practical and effective for its time. Additionally, some modern TVs may use additional primaries to enhance the color gamut, though RGB remains the most common and sensible choice for most devices.

Pixel Display and Vision Improvements: The use of RGB or CMYK depends heavily on the type of device and application. For example, in pixel display technology, RGB is ideal because it provides a wide color gamut and is easier to manipulate on digital screens. In contrast, CMYK is more common in physical printing due to the nature of ink and paper.

Conclusion: In summary, the preference for red and green in vision tests, particularly in detecting color blindness, is largely driven by occupational safety and the commonality of red and green deficiencies. While the visible spectrum and color theory use different methods, RGB and CMYK are practical choices for their respective applications. Understanding the differences helps us appreciate the nuances of color in both the digital and physical worlds.

Keywords: color theory, RGB, CMYK