Colour Theory

Last week and today, we had visually jarring lectures on colour theory. The first lecture touches on the way we perceive light while the second one is on subjective colour and the optical reaction that our eyes make when we stare at colours on different conditions and or contexts. Since I've learnt about the physics behind the colour spectrum prior to the lecture, I can appreciate the diffusion of white light when it passes through a slit or in between small particles producing different spectral colours as perceived by the eyes. In general, the greater the wavelength, the slower it travels, so it appears more reddish, while the shorter the wavelength, the faster it travels, the more purplish-blue it will be.

For instance, the sky is not pure blue because the particles floating in the air have different physical properties, they diffract light in different manners, therefore the blue is a combination of spectral colour which our eyes interpret as blue.

Mixing Colours

Fred also explained CMYK/substractive colour and RGB/additive colour and why the first is used for printing and the latter is used on screen.

Subjectivity and Optical Reaction of Colour

I find the lecture useful because I tend take the optical effect of the interaction between colours for granted, and attending the lecture allows myself to reflect on the subjectivity of colour. Despite having fixed codes of colour on Pantone colour system, the way out eyes perceive colours are still conditional and contextual, hence it is optically subjective. (The Pantone colour system is made by comparative colour matching so as to adjust the consistency of colour on the screen and on the printed material)

First thing first, we need to understand the factors that affect chromatic value represented by a simple equation.

Chromatic Value = Hue + Tone (Luminance) + Saturation

The effect of interaction between colours with different chromatic values depends on these 7 factors:

1. Contrast of TONE 
• Light - dark
2. Contrast of HUE 
• Difference in tonal value relative to the distance between the colours in the colour wheel
3. Contrast of SATURATION
• More like boldness of colour. The bolder it is the more pure it will be.
4. Contrast of EXTENSION
• The weight of colour to create visual balance.
• The distribution of colours in a composition affects the weight of a colour relative to another, the more widespread they are, the lesser the weight of the colour.
5. Contrast of TEMPERATURE
• Warm - cool (subjective interpretation)
• The longer we look at colours, the more we can feel the temperature difference
• As a result, our eyes can perceive flat colour gradients.
6. COMPLEMENTARY contrast
• On a neutral grey background, depending how bold the colour is, we'll be able to see the optical change of the neutral grey to the complementary colour of the bold colour if we stare at it for long.
• Proves that complementary colours imposes themselves on a neutral background.
7. SIMULTANEOUS contrast
• Optical illusion formed when all 6 factors are working together
• A physically same colour will be optically changed if placed on background with different chromatic value.