02 Nov Colour Vocabulary – Hue, Value & Saturation

As I wrote another post delving further into the exploration of the CMY colour primaries, I realised there are a bunch of terms I tend to use, which may be unfamiliar to some of you. Let’s take these commonly heard words from the colour vocabulary: Hue, Value and Saturation.

But first, a little history of how colour has been explained through the ages. If you want to skip the lecture and get down to the dirty, click here!

What is even colour?

The idea of colour has evolved through the ages as our information grows, and probably will continue to change. Perhaps our descendants 500 years later will look at it and explain it in a whole different way, and say’ once upon a time, they believe in explaining colour as a wheel, and had these strange terms like hue, saturation etc.’

I’m a sucker for information about things I’m obsessed with. While writing this (supposed-to-be) short blog post, I have taken detours to at least twenty different sites and articles before coming back here.

Aristotle (yes, that one, between the 350-380ish BC!) developed the first theory on colour at that time. His treatise was called ‘On Colors.’  He said they were celestial rays of light from heaven sent by no other than God himself. (Oooh!) Pure light was considered white or colourless, and all colours emerged from interaction of that colourless light with matter, and interacting with light and dark, or white and black. He also related them to the four elements – air, water, wind, and fire. These beliefs formed the first known colour theory, and were held as gospel for almost 2000 years, until a better theory came along, developed by Isaac Newton.

Issac Newton (yes, the one with the apple!) began to play with light and prisms in the 1660’s. Being a scientist, he sought to experiment and come to conclusions based on empirical knowledge. He published his findings as a book named ‘Opticks’- which turned out to be one of the greatest works in the history of science. His theory debunked all previously held ideas on colour.

Newton identified that white light consisted of the colours ROYGBIV which were visible to the human eye. This was the visible spectrum in a range of wavelengths, which include electromagnetic waves, infrared waves, UV rays and more, which have a range of technical applications.

Newton’s theories were heavily debated, and in many cases opposed by believers in the Aristotelian theories. A German poet and scientist Johann Wolfgang von Goethe (of the Goethe Institut- yep!)  published his own book ‘Theory of Colours’ which contradicted Newton’s theories and claimed it could not be treated as a mathematical calculation but was a subjective experience of the viewer. His views originated due to his association with painting and had a profound impact on many of the big names in the history of art, like Kandinsky, Hilma Af Klint, JMW Turner and more.

These two texts, while both speaking of colour, ended up showing the way for the two models of colour theory- The additive and subtractive models of colour. Here they are in short.

Additive colour theory:

The additive model applies to Light, where white light is made up of many wavelengths of (coloured) lights. Different colours are produced when lights of different colours (or wavelengths) are mixed in different proportions. This theory is Newtonian in origin.

We observe this daily, where White light (composed of many wavelengths of lights) falls on our world, objects, surfaces, etc. The object (for example- an apple), absorbs some light and reflects some. Incidentally, the light reflected by an object then falls on or into our eyes, appearing as the colour of the object. So the red apple, absorbs all other wavelengths except red, reflects red into our eyes and thus appears to be red in colour! White is the presences of all wavelengths, aka a white sheet of paper reflects all the light hitting its surface. Black indicates a complete absorption of all light, since that surface absorbs all the light falling upon it.

This is also visually explained by the Prism splitting a beam of (white) light into a rainbow of colours.

It is this model which applies to our digital devices, our tablets, phones, and monitors, to lighting a stage show, or to setting the mood in a film scene.

When we project ROYGBIV coloured lights onto the same space, we will find that the light combines to form white. They ‘add up’ to form white, hence – additive.

Subtractive colour theory:

The subtractive model applies to colour appearing on physical matter, such as paints and pigments. In this case, white pigment is truly a lack of other colours. Combining the primaries, or even ROYGBIV colours in paints will not produce a pure white, and in fact tends to get darker and darker till black or brown appears.

As pigments are physically mixed with each other, they keep darkening the mixture and neutralising each other.

It is called subtractive because the coloured pigments, subtract the necessary colours from white light.

Interaction of light and colour:

Here is a little something to tease your brain – When coloured light falls on a coloured surface, their interaction, is also subtractive in nature.

So, a yellow light falling on a green surface would make the surface appear blue (green minus yellow). BUT… our brain overrides the visual information from our eye, to tell us, that hey, that surface really is blue! Ok, this is getting into murky territory!  The whole concept of subtractive and additive colour models can take up a whole blogpost, nay, many more blog posts. But I just wanted to rein in with this basic description of them.

Here is a real life science experiment from the ‘Incredible Science’ Youtube channel, that shows this in action, using coloured lights (additive) and food colouring (subtractive).  (Watch from 1:08 to 5:47)

Jumping into the terms themselves!

Hue:

Hue is nothing but the simple, pure colour. Often, you will see these words used interchangeably, including here.

There is a subtle difference. The word colour can technically be used to talk about any particular version (darker, lighter, shade etc) of a hue, while the Hue represents the family of colour itself. But that difference is so subtle, so I also use the words interchangeably as that helps better understand these concepts.  Once you are familiar with the words, you will end up using them without necessarily defining them at each point.

So, Hue, for a tube of paint, is the pure colour that spills out when you open it. For a digital colour picker, it is denoted by a number, and technically represents the attribute of the physical light that is visible.

White, Black, and Grey don’t technically count as hues, though they are available as colours in digital or real paints. White is the presence of all wavelengths of light, black is the absence of all light.

But when it comes to mixing of colours, we will see the role White and Black must play.

Value:

This one is super important and can often be the make-or-break for a painting. Value is simply how light or dark something is. The brightest (also called highest value) being white and the darkest being black. Value is caused by the effect of light (and shadow at the absence of light.)

In digital colour pickers it is represented by B for Brightness or L for Lightness.

Each hue has its own value too, and a painting or an image has not just one value but a range of values within. It is this ‘range’ of values that provoke interest and guide the eye around the composition. Variation in value is also what helps objects appear three dimensional, and not flat.

Each hue can further have many value derivatives. Since value can range from white to black, mixing a range of white and black into a hue results in the various other versions of that hue – called ‘tints’ and ‘shades.’

Adding white to a hue -results in ‘tints’, adding black results in ‘shades.’

In the case of transparent media, we add water to dilute the pigment to create tints, rather than mixing white itself.

We can also mix a hue with grey. This creates ‘tones’. This also lowers the intensity or vibrance of the colour. Do you remember the phrase ‘toned down?’

This leads me to the third key component – aka Saturation!

Saturation:

This denotes how vibrant or intense that hue is. Usually in the case of paints, the colour’s saturation is the maximum when it is used straight from the tube (or pan). As we mix other pigments into it, they interact together losing their vibrance.

In our digital colour pick you get a higher range of saturation, because monitors are more capable of producing bright saturated colours than in paints. Though nowadays we find more neon and fluorescent options in paint which help us mimic the digital brightness we find on screens.

You will also hear these words associated with this – vividness, chroma, purity, etc.

You will see more grey, as the saturation of a hue is reduced. This is because the purity of the hue is getting reduced. It cannot become white or black by lowering the saturation since the saturation cannot affect the lightness or darkness of the hue. Also, each hue has its own value when desaturated, so like you see, the desaturated grey of a blue is different from that of a yellow, and

So there ends this not-so-quick breakdown.

This works exactly like this in all opaque media (be it pencils, paints or pastels) as well as digital media. Have you seen a digital colour picker? Next time, look out for these same terms here, Hue Value and Saturation, also seen as H, V and S, or H L S.

It is only in the way of mixing these that differs media to media.

In the case of Transparent media, there is a little twist to the tale.

Have you heard someone tell you to not use white in a watercolour work? While they do exist, white paint tends to be opaque and took away from the ‘transparent nature’ of watercolours. Mix more water ingo the colour mix to ‘reveal’ White!  This allows more of the paper white to show through the transparent colour, lightening it. (aka TINTs)

For shades, Black on the other hand, can be transparent. Mixing with it though, gives rather dull and boring dark valued colours. So how do we darken our colours during painting?

Hence there are two popular techniques (That I know/ figured out) to control the darkness of your watercolours.

You can tone them, aka play with their saturation, or you can darken with other hues rather than black.

I will explain both these methods in another blog post. This one is already too long! 😀

Edit:

This post is part 2 of a 5-part series on colour theory and the basics of the colour wheel. The others in the series are linked below.

1 Primary Colours?

2. Colour Vocabulary – Hue, Value and Saturation (this one)

3. The CMY Colour Wheel

4. Colour Temperature

5. Expanding the CMY colour wheel