What is a two-dimensional colour model?
The three types of colour models
There are three types of colour models: the trichromatic (three-colour) model, the four-colour CMYK model, and the seven-colour RGB model. Each type of model is based on a different number of primary colours.
The trichromatic (three-colour) model uses the three primary colours of light: red, green, and blue. This is the most basic type of colour model, and it is used in a variety of applications, including TVs, computer monitors, and digital cameras.
The four-colour CMYK model uses the four primary colours of ink: cyan, magenta, yellow, and black. This model is used in printing applications, as it allows for a wider range of colours to be printed.
The seven-colour RGB model uses the three primary colours of light (red, green, and blue), as well as the three secondary colours (cyan, magenta, and yellow). This model is used in a variety of applications that require a wider range of colours than what can be achieved with the trichromatic or four-colour models.
The RGB model
The RGB model is an additive colour model in which red, green and blue light are added together in various ways to reproduce a wide array of colours. The name of the model comes from the initials of the three primary colours, Red, Green and Blue.
The three primary colours
The RGB model is an additive colour model in which red, green and blue light are added together in various ways to reproduce a wide array of colours. The name of the model comes from the initials of the three primary colours, red, green and blue.
The main purpose of the RGB colour model is for the sensing, representation and display of images in electronic systems, such as televisions and computers. It is used in a variety of other applications including human colour perception models (e.g. celebrating Christmas with red and green decorations), computer graphics (video games and 3D rendering) and image processing (along with CMYK printing).
RGB is a device-dependentcolour model: different devices perceive or reproduce a given RGB value differently, since the gamut of each device is limited by its phosphors or dyes. Thus an RGB value does not define the same colour across devices without some kind of reference device. Typical references forRGB colour values are the CIE 1931 XYZ coordinates for white or D65 light; other specifications sometimes used include the 1976 CIELUV u′v′ coordinates orHunter Lab Luminance Y0 color space coordinates.
The three secondary colours
The three secondary colours are cyan, magenta and yellow. They are each made by mixing two of the primary colours together.
Cyan is made by mixing green and blue together.
Magenta is made by mixing red and blue together.
Yellow is made by mixing red and green together.
The CMYK model
The CMYK colour model is a subtractive colour model, based on the colour wheel, used in colour printing, and is also used to describe the printing process itself. CMYK centres on the three primary colours of pigment: cyan, magenta, and yellow. Black is added as the fourth printing ink colour to produce a full colour image.
The four process colours
The four process colours are cyan, magenta, yellow and black. These are the colours used in printing and can be combined to produce a wide range of different colours.
The CMYK model is a subtractive colour model, which means that it starts with white and subtracts colour from it to create other colours. The CMYK model is used in printing because it is possible to produce a wide range of colours using only these four colours.
Cyan, magenta, yellow and black are known as ‘primary’ colours because they cannot be produced by mixing other colours together. Cyan is made by adding blue and green together, magenta is made by adding red and blue together, and yellow is made by adding red and green together. Black can be created by mixing all three primary colours together, or by using black ink.
The four primary colours
The four primary colours in the CMYK model are cyan, magenta, yellow, and black. These are the colours that are used in printing. They are also the colours that can be seen on a computer screen when using a paint program.
The CMYK model is a two-dimensional colour model. This means that it uses two dimensions to describe a colour. The first dimension is hue, and the second is chroma.
The hue of a colour is its basic color. Cyan, magenta, and yellow are each a hue. Black is not a hue, but it is used in printing to darken other colours.
Chroma is the amount of saturation in a colour. A colour can be said to be more chromatic if it is more saturated, or less chromatic if it is less saturated. Saturation is sometimes described as the “intensity” of a colour.
The HSL model
HSL model is a more intuitive model than the RGB model. In the HSL model, there are three components: hue, saturation, and lightness. The hue represents the colour, the saturation represents the amount of grey, and the lightness represents the brightness.
The three dimensions of colour
HSL (hue, saturation, lightness) and HSV (hue, saturation, value, also known as HSB [hue, saturation, brightness]) are alternative representations of the RGB color model, designed in the 1970s by computer graphics researchers to more closely align with the way human vision perceives color-making attributes. In these models, colors of each hue are produced by combinations of additive primary and subtractive secondary colors (such as red, yellow, blue make white light); whereas in RGB color models, colors are produced by a combination of additive primaries alone (red green and blue make white light).
The HSL model is often used by graphics software such as Adobe Photoshop; while HSV is used by Microsoft Paint.
The six HSL colours
The six HSL colours are red, orange, yellow, green, blue and purple.
The HSV model
The HSV model is a colour model that represents colours in terms of hue, saturation and value. The hue is the colour, saturation is the amount of grey in the colour, and value is the brightness of the colour. This model is useful for representing colours in a more intuitive way.
The three dimensions of colour
The HSV model is often used by artists because it more closely resembles how we see colour. The H, S and V stand for Hue, Saturation and Value (sometimes called Brightness). In the HSV model, hue refers to the pure colour ( red , blue , etc.), saturation is a measure of how much grey is mixed in and value is how light or dark the colour is.
The six HSV colours
The HSV model was created by engineer Karl D. Lang in the 1950s. It is a computer model used to create colours on a screen. The letters H, S and V stand for Hue, Saturation and Value. The model is also sometimes called HSB (Hue, Saturation, Brightness).
There are six HSV colours: red, orange, yellow, green, blue and purple. Each colour has its own unique hue. To create a colour, the hue is combined with saturation and value.