ColorSpace (Model)

Physical

The physical focused colorspaces:

• target Machine
• are Non-linear (Non-uniform)

They uses the physical property of the pigment or light such as additivity and substractivity and is based on primary colors that are added/or substracted to create other colors.

Example:

• RGB - red green blue - the colors of the pixel used in monitor
• RYB - red yellow blue - the colors used in a projector
• CMYK - Cyan, Yellow, Magenta and black - the colors of the inks used in printing

This colorspace are non-linear, meaning that:

• an increase in one coordinate can lead to a really different color
• therefore the diff based on the coordinates has no real meaning.

Human

The human focused colorspaces:

• target Human perception
• are linear (Uniform)

They uses the human perception property of the color such as:

• hue
• saturation (colorfulness, with or without color)
• lightness (dark vs light)

The most known is:

• HSV
• CIELAB (a.k.a. Lab) - still color based but human colors.
• CIELChab (a.k.a. “LCh” or “HCL”)
• Dave Green’s Cubehelix

This colorspace are linear, meaning that the diff based on the coordinates has a meaning.

List

Conversion

See Numerisation to Printing process (Color Space Transformation)

• d3-color: from rgb to hsl

from rgb to hsl calculation

const color1 = d3.hsl("#075ebb") // hexadecimal RGB
console.log(`hue: ${color1.h} degree`);
console.log(`saturation: ${color1.s} `);
console.log(`lightness: ${color1.l} `);

• Qix (Node module)

var color = Color('#7743CE').alpha(0.5).lighten(0.5);
console.log(color.hsl().string());  // 'hsla(262, 59%, 81%, 0.5)'
console.log(color.cmyk().round().array());  // [ 16, 25, 0, 8, 0.5 ]
console.log(color.ansi256().object());  // { ansi256: 183, alpha: 0.5 }