Colour is the part of light that is reflected by the object we see.
Colour is an important element in any kind of artwork. Originally photography was thought of in monochrome, due to colour technology not being readily accessible in a relative inexpensive format until the 1960s. Now photographers have the luxury of choosing monochrome or colour with a variety of media available to exhibit the finished image.
Colour is the next section of the course so first of all I need to research the relation and theory of colour.
Colours can be divided into three main classifications:
Primary – red, blue and yellow
Secondary – a mix of two primary colours:
Blue/yellow mixed = green
Red/yellow mixed = orange
Blue/red mixed = purple (or known as violet)
Tertiary – colours are combinations of primary and secondary colours, the name of the tertiary colour is the combination of the primary and secondary colour with the primary colour coming first:
Mix blue with purple = blue purple this is a tertiary colour.
The common way of show the above relations is on an artist’s colour wheel, which I have drawn up in AutoCAD and pasted a jpg here:

Viewing the colour wheel: colours opposite each are complementary colours providing maximum contrast but maximum stability, for example: red-green, yellow-purple & orange-blue:

These are the basic combinations of primary and secondary colours.
There are also contrasting colours, this relationship is created by two primary or two secondary colours that are separated by at least one-third of the colour wheel e.g.
As shown above the colour wheel can also be divided into warm and cool halves as shown on the colour wheel above. The warm colours: reds, oranges and yellows, are associated with warmth, fire, sun, etc. where cool colours: greens, blues and violets are associated with sky, sea and leaves.
Further to the relationship between colours there are the qualities of colour, which can be described in terms of: Hue; Brilliance; Saturation.
Hue refers to the pure colour. The colours shown on the colour wheel are all hues.
Brilliance refers to the lightness or darkness of a colour. This is the intensity of a colour determined by how much or how little grey a colour contains
Saturation defines the intensity of the colour (hue). This is the intensity of a colour determined by how much or how little grey a colour contains. Vivid primary colours are saturated and pastel colours are unsaturated.
Black, white & grey are referred to as neutral colours.
There is a general descending order of light values for colours as defined by Johann Wolfgang von Goethe in 1810., which are:
Yellow-9, orange-8, red-6, green-6, blue-4 and violet-3.
These numbers can be used to read the comparison of colours to describe them Red and green have the same number (6) as they are judged to have the same luminosity. This means they also combine harmoniously when in equal portions.
Orange has twice the luminosity as blue. So to create balance blue has to be twice the area of orange, as shown here:

The brightest and darkest of the pure hues, respectively, are yellow (9) and violet (3) as shown below to create balance yellow is only a quarter of the image thus creating a weak:

Obviously colours come in multiple combinations with red/yellow/blue being the strongest mix of pure hues. These hues will work together in an image punctuating a photograph but if too many are collected together becomes excessive and confusing .
Above are some of the basics of colour theory I have looked into before undertaking the first exercises in Part 3 of TAOP – Colour.