Shedding some light on the mystery of Colour & Tone

and how this applies to the painting process

by Jacky Pearson

How do we see colour and tone?

A healthy human eye can disnguish up to 1 million colours! We have billions of colour and tonal receptors at the back of our eyes which respond to a small part of radiaon in the form of wavelengths and parcles.

“It is my opinion that as painters the more we understand the process of creang our art works, the be er the outcome.”

Light from the sun comes in the form of wavelength frequencies and scattered light due to dust and water droplets. Blue light scatters more than other colours, being shorter and more energetic. Distant objects like mountains seem bluer because the eye is seeing them through layers of scattered blue light which isoverpowering other colours. Thus the sky is blue.When the sun is low at sunset and the light is travelling an extra distance, there is much more scattering of blue light, so the red and orange longer wavelengths are more easily seen.

A rainbow occurs where visible light in the form of white radiation is refracted through millions of water droplets into component colours and those colours get sorted in order of wavelength. Violet and Blue have the shortest wavelength and therefore highest energy and can bend more than longer wavelengths. Violet and blue are seen beneath the warmer, longer wavelength colours which bend less.

The Electro Magnetic Spectrum

The diagram to the above shows energy from the sun, known as the Electromagnec Spectrum. We see only a small part of this radiation.

One end of the radiation spectrum is short, high energy such as nuclear, x-ray and UV. Next is the small section of visible light. Blue light is the shortest wavelength and therefore highest in energy. The less energetic wavelengths include infrared and radio waves.

We see an object as having a colour due to absorption and reflection by the object at a molecular level. A green apple absorbs all of the wavelength frequencies of visible light except for the green wavelengths. A red apple absorbs most of the green wavelengths and reflects the red.

Light and Shadow - Introducing Form and Cast shadows

There are two types of light: Direct(from the sun) and Ambient (from reflected light, or known as Secondary light source). This is very important to the artist since a shadow is the recipient of many complicated effects due to the type of light source.

Here the light is Direct creating the very white shape of the snowy mountain. Note the ambient light in the shadows collecting scattered blue light from the sky. Note the shadow is tonally darker than the sky.

See the shadows on this teacup spliting the cup in half with a soft edge running vertically. This is the Form Shadow. Where the cup is turned away from the light. Now look at the hard edge of the Cast Shadow from the handle and the saucer, A cast shadow falls on another object and its shape is dependant on the angle of light. Whereas the Form Shadow is on the object and is on the shaded side of that object. On a rounded form a Form Shadow is soft along the main edge.

Components of Form and Cast shadows

There are about 7 different components of a Form Shadow and 5 on a Cast Shadow.

FORM SHADOW
  1. Bleached out colour (any colour) of the direct light called the Highlight.
  2. The Lit Area where the object has strong lighting on it but colour is visible.
  3. Halftone area, that blurred transition next to the Lit Area and where the true colour resides. Here there is more intense colour of the true overall colour of the object.
  4. Core Shadow: a no man’s land as it were. Always a cooler and darker slither of shadow helping the eye create a sphere or rounded surface. It is trapped light between the Lit Area and the Reflected Light Area.
  5. Reflected Light beyond the Core Shadow and taking up secondary ambient light from another adjacent object.
  6. Crevice Shadow is where there is no light so is very dark.
CAST SHADOW
  1. Umbra and penumbra.
  2. Soft Edges further away
  3. Harder Edges nearer to the object.
  4. Terminator Shadow, blur on the shadow edge.
  5. Reflected Light, contrary to some opinions cast shadows do contain reflected light from the object casng the shadow

Reflected Light in the Shadows

Here my hand shadow is capturing reflected light from the sky and from my hand. Overall, the shadow is on the blue side. A cast and form shadow are full of colour!

Observe how a cast shadow is a darker version of what it is falling over. You will also take in the scattered blue light that is always within an area of shadow.

Observe how on the cool grass the shadow is dark green and on the pomegranate the shadow is warmer and more orange. Both are still cool containing plenty of blue. Note the blurry red edge shadow (Terminator shadow).

This was an amazing photograph I took of a duck with an almost complete visible spectrum of colours in order down its form shadow! Under the duck’s neck is the influence of the blue sky, then as the chest comes around there is the influence of the grass and finally the yellow, orange and red influence of the legs.

But how do we see Colour? And what makes an object have a colour?

Back in the day, conducting research into spectral analysis of soil types and vegetation, I used an artist’s version of analysing colour for soil and his name was Albert Munsell. His “Colour Notation” was used by many disciplines of scientist and art. Little did I know I would be coming across Albert Munsell later in my art journey!

At the back of the eye reside millions of colour and tonal receptors. Armed with their particular proteins, sensitive to wavelengths and light. They sort a part of the Electromagnetic Spectrum that allows our brain to make sense of form and space. Tonal receptors are skinny and resemble rods and colour receptors are cone shape. There are approximately 120 million rod cells that do not pick up colours but allow us to see in low light. Rod shaped cells allow us to see tonal variations in dim light and colour receptors, which are cone shaped, dependant on strong light and are sensive to colour.

We have about 6 million cone cells sensitive to long visible wavelengths (roughly translated red), medium wavelengths/(green) and short, high energy wavelengths/(blue). We see more variations in green because our medium wavelength receptors are more numerous. Magenta has no wavelength and is an exception and we mix signals for the short and long wavelength cells (blue and red) to make it. Our brain does quite a bit of alternave processing! To make sense of a dull colour we mix tonal and colour receptors.

Munsell Color System

At the turn of last the century, American artist, Albert Munsell, with the help of leading scientists and artists, developed a way of understanding what colour is, and developed the Hue, Tone and Chroma concept. He has been a huge influence in science and art.

As a general rule when painting I stick to this:

Far - Near
Cool - Warm (hue)
Light - Dark (tone)
Dull - Bright (chroma)

Simultaneous Contrast, Colours are determined by what is adjacent

When complementary colours, light - dark and dull - intense colours are next to each other we see one or the other more intensely.


Dull against bright contrast

Complementary colours: red and green

Light against dark contrast

Alternavely you can use complementary colours in a mix and achieve beauful greys!

Reflections are mirror images that are always duller than the object colour because light bends and gets distorted on the surface which is never quite a mirror. A reflection is also the opposite in tonal value unless it is a midtone when it is the same tone.

It is interesting to note that if you have a cataract, a yellow discolouration of the lens you will be filtering out the shorter blue and greener wavelengths and seeing more of the longer yellow orange and red wavelengths. Another interesting point is that since blue wavelengths are shorter high energy and more abundant staring at our computer screens is the equivalent of staring at the sky for hours which is why too much screen time is quite harmful to our eye health!

Solution ... paint more!