A screen uses varying amounts of light to create the colours that you see. In the physical world, inks are used to create the colour on the page. Colour is stored by turning colours into numbers. A colour model is used to describe the numerical system used.
As not all devices have the same ability to display colour, a colour space is used to define the gamut (available range) of colour. By working within a colour space suitable for the intended output device, you can be confident that your colours will be able to be displayed as intended.
You can use an RGB workflow or take advantage of an end-to-end CMYK or Lab colour-managed workflow as you create a new document instead.
About colour models
Different colour models represent colour as numbers in different ways. You can choose one of four colour models.
RGB model
The RGB model is an additive colour model. The primary colours of light, Red, Green and Blue, are combined in various degrees to make other colours in the spectrum.
A representation of the RGB colour model. This model is universal within digital cameras and electronic displays.
CMYK model
The CMYK model is a subtractive model. Cyan, Magenta and Yellow are combined to make each colour. A fourth ink, Black, is also used for extra control and can be used either on its own for a true black, or combined with the other inks for a rich black.
A representation of the CMYK colour model. When the three colours combined they make black. Black is also added as a separate colour for extra tonal control.
Lab
Lab colour represents the theoretical range of human vision using three channels: Lightness (L), and two colour channels of opposing values of 'red - green' (a) and 'yellow - blue' (b). It can be very useful when used creatively, especially as Lightness can be adjusted without any change to hue or saturation.
A representation of the Lab colour opposition model. Lightness (L) is controlled separately to the two colour channels (a, b).To select a new document's colour space:
As you create a new document, select a colour format and profile from the Colour tab.
To change your document's colour model at any time:
From the File menu, select Document Setup.
From the Colour Format pop-up menu, select any of the available models as described above.
Publisher converts each colour from the old format to the new one—colour/pixel values may change as a result.
