We have all grown up knowing what colour is, but in order to understand it clearly and to gain a better grasp of how we use it, perceive it and differentiate one colour from another, it is necessary look at a precise definition in order to know how colour works. Whether you are printing, vinyl cutting, laser cutting, using a CNC Router or Heat Press, it is vital that you understand colour.

One definition is as follows: “the property possessed by an object of producing different sensations on the eye as a result of the way it reflects or emits light.” Another more scientific definition is “In physics, colour is associated specifically with electromagnetic radiation of a certain range of wavelengths visible to the human eye.”

While these are adequate definitions, another would be the differing wavelengths of light which reflect off an item. Each colour that we see is made up of a different wave length of light. However, it is important to note that no two people will see the same colour in exactly the same way.

According to Wikipedia, The physical colour of an object depends on how it absorbs and scatters light. Most objects scatter light to some degree and do not reflect or transmit light specularly like glasses or mirrors. A transparent object allows almost all light to transmit or pass through, thus transparent objects are perceived as colourless. Conversely, an opaque object does not allow light to transmit through and instead absorbing or reflecting the light it receives. Like transparent objects, translucent objects allow light to transmit through, but translucent objects are seen coloured because they scatter or absorb certain wavelengths of light via internal scatterance.

So, how many colours can a person see. The visible colour spectrum, visible by humans that is, is around 16,7 million colours. That is an awfully big number of colours and there is very little chance that most people will ever have to distinguish all of those colours from each other. This is a good thing because although the human eye can accurately see and distinguish all those colours. There is also no way you could name them all and there is almost no need to use all of those colours. Another factor is that if all people experience colours differently, what one persons sees will be different to what another person sees. This is not colour-blindness, it is just a difference in the ways one person’s eyes experience a colour compared to another. Colour-blindness is a totally different thing and causes its own set of problems.

To truly, accurately and correctly measure colour, specialist devices known as spectrometers, densitometers and colour spectrophotometers are required. However, even here just scanning the colour with one or all of these devices will not necessarily produce an accurate result. In order for these devices to obtain an accurate result, the lighting has to be correct.

As a result, colour is a very subjective element, but at the same time it is highly important. Looking at the same item under fluorescent light compared to daylight will produce very different optical results. However, as human being we rely on colour for differentiation. And colour becomes important, especially when we assign a specific colour to important items. Think of corporate logos or the colour of food.

When it comes to printed colour, it is important to understand other details such as how the ink is made and what the ink comprises. How will the item be printed and how the ink dries and whether it sits on the substrate or is absorbed by the substrate.

It is also important to understand that the way colour is experienced depends on the method in which it is displayed. Printed colours are vastly different from the colours seen on a screen. This is for the simple reason that screen colours are made up of the primary colours Red, Green and Blue -RGB – while printed colours are made up of the secondary colours of Cyan, Magenta, Yellow and Black – CMYK. In primary colours black is not a colour but the absence of light, while in secondary colours Black – represented by the symbol for potassium K – is an actual colour.

The chart below shows colours 1, 2 and 3 as Green, Blue, Red. Where these colours overlap you get the secondary colours 4 Cyan, 5 Yellow, 6 Magenta and 7 Black. In the image it is actually white, but in this format of representing colour – white is measured as 0% Black.

From here you can see how there could be a total of 16,7 million colours because if you take one colour comprising 11% Cyan, 17% Yellow, 33% Magenta and 5% Black this would be a different colour to 11% Cyan, 17% Yellow, 33% Magenta and 6% Black. The colour difference would be virtually imperceptible to the human eye, but there is a difference and it is measurable.

Colour is a very technical subject, far too detailed to go into any great depth here. However, it is important to know that when you are editing or adjusting colour there are a number of ways in which it can be done. You can adjust the individual percentage of a single colour, you can adjust the Hue Saturation and Lightness, you can adjust the density and brightness. It is necessary to understand that adjusting one element or variable on one colour can have a corresponding affect on the other colours. As an example, as the brightness of the yellow increases, it can appear to influence, or even directly influence the other colours making up the image.

Colour editing is something that most people take for granted with the modern technology and software that is available. However, these solutions have only achieved the level of sophistication that they have through many years of meticulous and painstaking study into the field of Colour.

While colour may be something that most of us think of as either aesthetically pleasing or not, the process of working with colour is very important in the signage industry. Colours have to match the original as precisely as possible and must take into account where it will be displayed. Think of the Nedbank signage, as an example. Nedbank has a very specific green as its corporate colour. Now consider the difference in “colour appearance” when that signage is displayed indoors compared to the same sign displayed in full sunlight with the sun falling directly on the image. Compensation must be made for how and where the image will be displayed in order for the same colour to be seen in the two different locations and lighting.

This scenario also comes into play when considering the inks used and the substrate selected. The type of ink used also has to consider where the image is displayed and the substrate it will be printed onto among other factors. All of these are important and nothing should be overlooked.

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