A colour, to a computer, is nothing more than a collection of numbers – without soul, subjectivity or emotion.

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A colour, to a computer, is nothing more than a collection of numbers – without soul, subjectivity or emotion. 

Humans on the other hand perceive colour in so many ways you would need to be a chemist, biologist, neurologist, psychologist and philosopher all rolled into one to appreciate the impact it has on our daily lives.

We most generally encounter man made colour in two fundamentally differing ways:
  •  On electronic display screens (computers, phones, TVs, etc) where the colour is the result of projected or emitted light
  • In printed forms, where the colour is a result of pigments, dyes or whatever else is placed on the printing surface (substrate)

RGB colour


RGB colour is what you are most likely looking at right now (unless you have printed this page on paper!). RGB colour is made up of Red, Blue, and Green light. Where colours mix, their waveforms merge to create secondary colours.Computers generally display colour onscreen using a pallette of 16.8 Million colours.This number is not arbitrary. It is the result of each component colour (red, blue, green) being represented by any value from 0 (black/off) to 255         (brightest/on), and 255 x 255 x 255 = 16,777,216!


RGB colour can also come in 16bit flavors – where each component is represented by 65,535 levels of brightness, far more resolution than the human eye can perceive the advantage of using such a deep colour system is that editing, filtering and manipulation can take place without loosing perceptual image quality in the end result.

CMYK colour

CMYK colour is what you are most likely looking at when you read a magazine or most other things that are printed on a commercial press. CMYK colour is made up of four colours – Cyan, Magenta, Yellow and Black. Each component colour is represented by a percentage from 0 to 100. This provides an even larger number of colour combinations than RGB.
Just as RGB has it’s supercharged 16bit cousin, so CMYK also has other more exotic flavours, such as Hexachrome, and CcMmYK which provided a broader colour gamut by using more inks. Gamut? 


colour gamut




So now we have a basic understanding of how colour is produced on screen and in print. Perhaps the next thing to appreciate is something called Gamut. There are many articles regarding Gamut that go into incredible technical detail and use the most groovy of diagrams, one of which I have included here. However, this can quickly lead to cranial meltdown, so I’m going to attempt a simple conceptualization 









Introducing Colour Profiles

A Colour Profile is a way of describing how a particular system displays colours.

Some profiles, are really colour spaces in their own right. sRGB, and Adobe 1998 are two common examples. However, basically speaking, they are just different ways of describing how to convert CIE colours into RGB values. sRGB is widely used in the TV industry (also the standard for the web), and Adobe 1998 being widely used in Photography due to it’s broader gamut.

In the print industry, the FOGRA27, Europress and SWOP CMYK profiles offer standardised gamuts for CMYK printing based on various standard print processes.

Bringing it together

A colour managed workflow relies on three components:
  •  Devices (screens, printers, scanners, cameras)
  • Profiles (device dependent and independent)
  • Conversion engine (to carry out the conversion from one profile to another)

"Color management" is a process where the color characteristics for every device in the imaging chain is known precisely and utilized in color reproduction.

In digital photography, this imaging chain usually starts with the camera and concludes with the final print, and may include a display device in between:

Putting it all together, the following diagram shows how these concepts might apply when converting color between a display device and a printer:



So as you can see, almost every system of colour reproduction in the world can be given a colour profile to describe how it can best duplicate the colours in the standardised CIE Colour Space.

If we have a mathematical way of describing how every colour system should work with reference to the CIE standard colour space, then it is just a case of some further maths to work out how to convert the numbers from one colour system into another.





Sources : cambridgeincolour, sant-media, encyclopedia britannica

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