The Science and Art of Colour and Methods of Colour Reproduction Explained
Colour And Methods Of Colour Reproduction Ebook
Colour is one of the most fascinating aspects of our visual experience. It enriches our perception of the world and influences our mood, emotions and preferences. But how do we see colours? How do we measure them? And how do we reproduce them accurately on different devices and media?
Colour And Methods Of Colour Reproduction Ebook
In this article, we will explore the answers to these questions and more. We will learn about the science and art of colour, the methods and technologies of colour reproduction, and the challenges and solutions of colour management. We will also introduce you to a comprehensive and practical ebook that will teach you everything you need to know about colour and methods of colour reproduction.
What is colour?
Colour is not a physical property of objects, but a subjective sensation that depends on the interaction between light, matter and our visual system. To understand what colour is, we need to consider three aspects: light, object and observer.
Light is electromagnetic radiation that has different wavelengths and frequencies. The visible spectrum of light ranges from about 380 nm (violet) to 780 nm (red). Different wavelengths of light correspond to different colours that we perceive.
Object is anything that reflects, absorbs or transmits light. The colour of an object depends on its surface properties, such as texture, glossiness and pigmentation. An object can reflect some wavelengths of light more than others, creating a characteristic colour appearance.
Observer is a human being who has a visual system that can detect and interpret light signals. The observer's eyes have photoreceptors called cones that are sensitive to three primary colours: red, green and blue. The observer's brain processes the signals from the cones and creates a mental representation of colour.
Therefore, colour is a perceptual phenomenon that results from the combination of physical stimuli (light), physical attributes (object) and psychological factors (observer).
How do we perceive colour?
The process of colour perception involves three stages: physical, physiological and psychological.
Physical stage: Light from a source (such as the sun or a lamp) reaches an object (such as a flower or a painting) and is reflected, absorbed or transmitted by it. The reflected or transmitted light then travels to the observer's eyes.
Physiological stage: The light enters the observer's eyes through the pupil and lens, which focus it on the retina. The retina is a layer of tissue at the back of the eye that contains millions of photoreceptors called rods and cones. Rods are responsible for night vision and low-light conditions, while cones are responsible for daylight vision and colour vision. There are three types of cones: L-cones (long-wavelength sensitive), M-cones (medium-wavelength sensitive) and S-cones (short-wavelength sensitive). Each type of cone responds to a different range of wavelengths of light, corresponding to the primary colours of red, green and blue. The signals from the cones are then transmitted to the optic nerve, which carries them to the brain.
Psychological stage: The signals from the optic nerve reach the visual cortex, which is the part of the brain that processes visual information. The visual cortex performs various operations, such as edge detection, colour constancy, colour contrast and colour categorization. The visual cortex also integrates the colour information with other sensory inputs, such as memory, emotion and language. The result is a subjective and meaningful experience of colour.
Thus, colour perception is a complex and dynamic process that involves both physical and mental aspects.
How do we measure colour?
To measure colour objectively and quantitatively, we need to use mathematical models and numerical systems that describe colour in terms of numerical values. These are called colour models and colour spaces.
Colour model is a theoretical framework that defines how colours can be represented by a set of parameters. For example, the RGB colour model defines colours by three parameters: red, green and blue. The RGB colour model is based on the additive colour mixing principle, which states that any colour can be created by adding different amounts of red, green and blue light.
Colour space is a specific implementation of a colour model that defines the range and accuracy of colours that can be represented by a set of numerical values. For example, the sRGB colour space is a standard colour space that defines how colours are represented by 8-bit values (from 0 to 255) for each of the red, green and blue parameters. The sRGB colour space is widely used for digital images and displays.
There are many different colour models and colour spaces that are used for different purposes and applications. Some of the most common ones are:
RGBAdditive colour model based on red, green and blue primariessRGB, Adobe RGB, ProPhoto RGB
CMYKSubtractive colour model based on cyan, magenta, yellow and black primariesISO Coated v2, US Web Coated (SWOP) v2, Japan Color 2001 Coated
HSVCylindrical colour model based on hue, saturation and value parametersN/A
HSLCylindrical colour model based on hue, saturation and lightness parametersN/A
LABPerceptual colour model based on lightness, a* (green-red axis) and b* (blue-yellow axis) parametersCIELAB, CIECAM02-JCh
XYZAbsolute colour model based on tristimulus values that correspond to the human cone responseCIE XYZ, CIE xyY
How do we reproduce colour?
To reproduce colour accurately and consistently on different devices and media, we need to use methods and technologies that can convert colours from one colour space to another. These are called colour reproduction methods and devices.
There are three main types of colour reproduction methods: subtractive, additive and hybrid.
Subtractive colour reproduction
Subtractive colour reproduction is a method of creating colours by subtracting or filtering out some wavelengths of light from a white light source. This method is used for printing and photography.
Printing is a process of transferring ink or toner onto paper or other substrates. Printing uses the CMYK colour model, which is based on the subtractive colour mixing principle. This principle states that any colour can be created by subtracting different amounts of cyan, magenta, yellow and black ink or toner from white paper. Printing devices include printers, copiers and presses.
Additive colour reproduction
Additive colour reproduction is a method of creating colours by adding or emitting different wavelengths of light from a black background. This method is used for display and projection.
Display is a process of showing images on a screen or other devices. Display uses the RGB colour model, which is based on the additive colour mixing principle. This principle states that any colour can be created by adding different amounts of red, green and blue light. Display devices include monitors, TVs and smartphones.
Projection is a process of projecting images onto a screen or other surfaces. Projection uses the RGB or CMY filter system, which is based on the additive colour filtering principle. This principle states that any colour can be created by filtering out some wavelengths of ligh