Color Space: Exploring the Spectrum of Computer Vision

By Fouad Sabry

What is Color Space

A color space is a particular arrangement of colors in a given space. In conjunction with color profiling, which is supported by a variety of physical devices, it is capable of supporting repeatable representations of color, regardless of whether such representations involve an analog or a digital representation. It is possible for a color space to be arbitrary, in which case the colors that are physically realized are allocated to a set of physical color swatches that have matching color names, or it can be structured with mathematical precision. The concept of a "color space" is a helpful conceptual tool that may be utilized to gain a knowledge of the color capabilities of a certain digital file or device. In the process of attempting to replicate color on a different device, color spaces can indicate whether or not shadow/highlight detail and color saturation can be preserved, as well as the degree to which either of these aspects will be diminished.

How you will benefit

(I) Insights, and validations about the following topics:

Chapter 1: Color space

Chapter 2: RGB color model

Chapter 3: CMYK color model

Chapter 4: RGB color spaces

Chapter 5: HSL and HSV

Chapter 6: Chromaticity

Chapter 7: CIELAB color space

Chapter 8: Gamut

Chapter 9: Grayscale

Chapter 10: Adobe RGB color space

(II) Answering the public top questions about color space.

(III) Real world examples for the usage of color space in many fields.

Who this book is for

Professionals, undergraduate and graduate students, enthusiasts, hobbyists, and those who want to go beyond basic knowledge or information for any kind of Color Space.

• Language: English
• Publisher: One Billion Knowledgeable
• Release date: May 10, 2024

Book preview

Chapter 1: Color space

A color space is a predetermined layout for color coding. When used in tandem with color profiling, which is supported by a wide range of physical devices, it enables accurate color reproduction, regardless of whether the color is being represented analogically or digitally. It is possible to assign colors arbitrarily, as in the Pantone collection, where each color is represented by a name and a number, or with mathematical precision, as in the sRGB color space (as with the NCS System, Adobe RGB and sRGB). The term color space refers to a useful mental model for figuring out the range of colors that a given device or digital file can display. Color spaces reveal how much shadow and highlight detail and color saturation will be lost when transferring colors to a different device.

A color model is an abstract mathematical model that describes how colors can be represented as tuples of numbers (such as in RGB or CMYK); however, a color model without an associated mapping function to an absolute color space is a more or less arbitrary color system that is not tied to any universally accepted system of color interpretation. For a given color model, a color space is defined by the addition of a mapping function between the color model and a reference color space. This mapping function leaves a footprint, or gamut, in the reference color space. Examples of absolute color spaces include Adobe RGB and sRGB, both of which are based on the RGB color model. The CIELAB and CIEXYZ color spaces are typically used as the gold standard for creating a color space because they were developed to provide all visible colors to the human eye.

The term color space is commonly used to refer to a color model informally due to the fact that it uniquely defines a certain color model and mapping function. While it's true that naming a color space will reveal the corresponding color model, this isn't the acceptable usage. While the RGB color model serves as the basis for a number of different color spaces, there is no such thing as the RGB color space..

Thomas Young proposed in 1802 that the eye contains three distinct types of photoreceptors (today called cone cells), each of which is sensitive to a different color of light. After further developing the Young-Helmholtz theory in 1850, Hermann von Helmholtz proposed that the three types of cone photoreceptors could be categorized as short-preferring (blue), middle-preferring (green), and long-preferring (red) according to their response to the wavelengths of light striking the retina. The visual spectrum is constructed by the brain from the relative intensities of the signals detected by the three types of cones. It's unclear, though, whether or not they envisioned colors as discrete locations on a color space.

Hermann Grassmann is widely credited with developing the idea of color space during a two-stage process. First, he came up with the concept of vector space, which allowed geometric concepts to be represented algebraically in n-dimensional space.

Around 1920, when formal definitions were published by Hermann Weyl and others, the concept of a linear space (vector space) entered the common lexicon. A definition along these lines was actually provided thirty years before, by Peano, who was very familiar with Grassmann's mathematical work. Although Grassmann did not formally define it, since the necessary vocabulary did not exist at the time, the idea was undoubtedly on his mind.

Based on these ideas, Grassmann published his theory of color mixing in 1853; today, students still learn about Grassmann's law and its three color laws.

In printing, the subtractive primary colors of pigment are used in conjunction with the cyan, magenta, yellow, and black (CMYK) color model to create a wide range of colors (cyan, magenta, yellow, and black). When representing a color space in three dimensions, the magenta component can be placed on the X axis, the cyan component on the Y axis, and the yellow component on the Z axis. Every hue that may be made by mixing those three pigments has a specific location in the resulting three-dimensional space.

In the RGB color paradigm, the additive primary colors are used to create colors on computer monitors (red, green, and blue). Each of the three hues could be associated with one of the three coordinate axes in a three-dimensional illustration. Keep in mind that the phosphor (in a CRT monitor) or filters and backlighting will affect the colors displayed on your screen (LCD monitor).

Colors can also be created on a screen using a model based on hue, saturation, and value (brightness). Cylindrical coordinates are used for the variables in such a model.

Some color spaces contain more or fewer dimensions, and some, like Pantone, cannot be represented at all in this way, but the vast majority of color spaces may be expressed as three-dimensional values in this fashion.

The process of converting between different color spaces is called color translation. The purpose of this is to make the translated image look as close to the original as possible, which occurs most often when translating an image from one color space to another.

There are numerous RGB color model implementations, Depending on the system's capabilities.

As of 2021, the 24-bit implementation has become the most often used version, using a binary system of 8-bits, or 256 levels of grayscale for each color channel.

Any color space based on such a 24-bit RGB model is thus limited to a range of 256×256×256 ≈ 16.7 million colors.

In some systems, each component occupies 16 bits, for a total of 48 bits, meaning the same range of colors but more of them.

When dealing with wide-gamut color spaces, this becomes crucial (where most of the more common colors are located relatively close together), Alternatively, when a large number of sequential digital filtering methods are utilized.

The same rule holds true for any color model-based color space, nevertheless, implemented with varying bit depths.

One of the earliest attempts to create a color space based on measurements of human color perception was the CIE 1931 XYZ color space (James Clerk Maxwell also made an attempt), König & Dieterici, & Abney at Imperial College) and serves as the foundation for virtually all other color spaces.

A linear extension of the CIE XYZ color space, CIERGB.

The CIELUV is another offshoot of CIE XYZ, CIEUVW, and CIELAB.

Because it specifies how much of each type of light must be emitted to create a specific color, RGB is an additive