The "Geometry" of Colours
Audio Brief
Show transcript
This episode delves into the scientific and philosophical quest to define and organize color, exploring its physical properties, biological basis, and subjective perception.
There are four key takeaways from this discussion. First, color is not an inherent property of objects but a subjective sensation created by the brain. Second, all colors can be mapped and organized within a three-dimensional space defined by hue, saturation, and brightness. Third, modern color science focuses on creating perceptually uniform color spaces, where mathematical distance corresponds to visual difference. Finally, human color vision is fundamentally shaped by our biology, specifically the three types of cone cells in our eyes.
Our perception of color is a biological and psychological phenomenon. The brain actively constructs color based on light wavelengths received by the eye, making it a sensation rather than an intrinsic attribute of an object. This means colors are feelings and subjective interpretations.
This subjective sensation can be precisely organized using a three-dimensional model. Hue describes the pure color such as red or green, saturation measures its intensity or purity, and brightness indicates its lightness or darkness. This framework is foundational for color science, mapping the entire spectrum of human vision.
Early color models, like Isaac Newton's color circle, did not accurately reflect human perception. Contemporary spaces, such as CIELAB and Oklab, are designed so that equal steps in their geometric representation correspond to equally perceptible differences in color. This perceptual uniformity is critical for digital imaging and scientific applications, ensuring consistency across various media.
The biological basis of our rich, three-dimensional color perception lies in our three-receptor visual system. Our eyes contain three types of color-sensitive cone cells, each tuned to different wavelengths of light. This trichromatic vision underscores how our evolutionary history and specific biology directly shape our interaction with the visible spectrum.
These insights highlight the complex interplay of physics, biology, and psychology in our everyday experience of color.
Episode Overview
- The episode explores the scientific quest to define and organize color, moving from early philosophical ideas to modern mathematical and psychological models.
- It breaks down the physics of light, explaining how white light is composed of a spectrum of colors and how objects interact with it to produce the colors we see.
- The video details the biological basis of color vision, focusing on the three cone receptors in the human eye and how this leads to a three-dimensional perception of color.
- It traces the evolution of color spaces, from Isaac Newton's color wheel to the perceptually uniform models like CIELAB and Oklab used today in digital imaging and science.
Key Concepts
- Color as Perception: Color is not an intrinsic property of an object but a subjective sensation created by the brain's interpretation of light wavelengths received by the eye.
- Visible Spectrum: Sunlight can be decomposed by a prism into a one-dimensional continuum of pure colors, from red to violet.
- Color Dimensions: All colors can be described using three properties: Hue (the pure color, e.g., red, green), Saturation (the intensity or purity of the color), and Brightness (the amount of light, from black to white).
- Additive vs. Subtractive Mixing: Additive mixing involves combining light sources (like on a screen), where mixing leads to lighter colors (R+G+B = White). Subtractive mixing involves pigments (like paint), where mixing absorbs light and leads to darker colors.
- Color Spaces: Geometric models used to represent colors mathematically. The video covers the evolution from Newton's Color Circle to the CIE XYZ standard, and finally to perceptually uniform spaces like CIELAB and Oklab.
- Perceptual Uniformity: The goal of modern color spaces is to be "perceptually uniform," meaning the geometric distance between any two colors in the space corresponds to how different they appear to the human eye.
Quotes
- At 01:16 - "Colours are feelings, subjective perceptions created by our brain when our eyes receive light." - This quote establishes the core premise of the episode: color is a biological and psychological phenomenon, not just a physical property.
- At 02:58 - "Newton understood that the white light from the sun results from a mixture of all hues of the spectrum." - This highlights a foundational discovery in the physics of color, explaining that complex light is composed of simpler, pure colors.
- At 12:31 - "The distances in the diagram have nothing to do with our perception of the differences between colours." - This quote explains the key limitation of early physical color models and sets up the need for perceptually uniform spaces developed later.
Takeaways
- Understand that color is a subjective experience created by your brain, not an inherent quality of the world around you.
- Recognize that all colors can be mapped and organized within a three-dimensional space defined by Hue, Saturation, and Brightness.
- Appreciate that modern color science focuses on creating "perceptually uniform" color spaces, which are designed so that the mathematical distance between two colors matches how different they look to a human observer.
- The way we see color is a direct result of our evolutionary history and the specific biology of our eyes, which have three types of color-sensitive cone cells.
