This was a Homework task set by Simon Klein to research Colour Theory, Additive Colour and Subtractive Colour. Here are the documents I wrote for this task:
In Art, “colour theory” is a body of practical guidance to colour mixing and the visual effects of a specific colour combination. There are also definitions (or categories) of colours based on the colour wheel: primary colour, secondary colour and tertiary colour.
Primary Colour: Any of a group of colours from which all other colours can be obtained by mixing.
Secondary Colour: A colour resulting from the mixing of two primary colours.
Tertiary Colour: Tertiary colours are the resulting colour formed when an equal amount of a primary and a secondary colour are mixed. The primary and secondary colour must be beside each other on the colour wheel. For example, a mixture of 50-percent red and 50-percent magenta would result in the tertiary colour of orange.
One of a pair of primary or secondary colours opposed to the other member of the pair on a schematic chart or scale (colour wheel) as green opposed to red, orange opposed to blue, or violet opposed to yellow.
Colour psychology is the study of hues as a determinant of human behaviour. Colour influences perceptions that are not obvious, such as the taste of food. Colours can also enhance the effectiveness of placebos.
Colour psychology is also widely used in marketing and branding. Many marketers see colour as an important part of marketing because colour can be used to influence consumers’ emotions and perceptions of goods and services.
Companies also use colour when deciding on brand logos. These logos seem to attract more customers when the colour of the brand logo matches the personality of the goods or services, such as the colour pink being heavily used on Victoria’s secret branding.
However, colours are not only important for logos and products, but also for window displays in stores. Research shows that warm colours tended to attract spontaneous purchases, despite cooler colours being more favourable.
An impression of a vivid image retained by the eye after the stimulus has ceased.
An After-Image is a type of optical illusion in which an image continues to appear briefly even after exposure to the actual image has ended. There are two major types of After-Images: positive After-Images and negative After-Images.
In a positive After-Image, the colours of the original image are maintained.
Essentially, the After-Image looks the same as the original image. You can experience a positive After-Image yourself by staring at a very brightly lit scene for a period of time and then closing your eyes. For the briefest of moments, you will continue to “see” the original scene in the same colours and brightness.
The exact mechanisms behind positive After-Images are not well understood, although researchers believe that the phenomenon might be related to retinal inertia. The original image stimulates nerve impulses, and these impulses continue for a small window of time after you close your eyes or look away from the scene. The cells in the retina take some time to respond to light, and once the cells have been exposed it takes some time for that response to cease. While positive After-Images happen quite frequently, we are generally unaware of them because they are so brief, often lasting as little as 500 milliseconds.
In a negative After-Image, the colours you see are inverted from the original image. For example, if you stare for a long time at a red image, you will see a green After-Image. The appearance of negative After-Images can be explained by the opponent-process theory of colour vision.
You can see an example of how the opponent-process works by opening this image of a red shamrock outlined in blue in a separate window.
Stare at the image for about one minute before shifting your gaze immediately to a white sheet of paper or a blank screen.
After staring at the shamrock, you probably experienced a green and yellow afterimage for a very brief moment of time. According to the opponent-process theory of colour vision, staring at the original red and blue image involved using the red and blue parts of the opponent-process cells. After that minute of extended staring, the ability of these cells to fire action potential was exhausted. In others words, you basically wore out those red-blue cells.
When you shifted your focus to a blank, white screen, those cells were still unable to fire and only the green/yellow opponent process cells continued to fire action potentials. Since the light reflecting off your screen could only activate those green and yellow cells, you experienced a brief After-Image in green and yellow rather than in red and blue.
You can also see an example of negative After-Images at work in an interesting visual illusion in the negative photo illusion. In this illusion, your brain and visual system essentially create a negative of an already negative image, resulting in a realistic, full-colour After-Image.
Opaque: Not able to be seen through; not transparent.
Translucent: (of a substance) allowing light, but not detailed shapes, to pass through; semitransparent
How do you paint a flat area of colour (Not Textured)?
With the specific paints on the pallet, mix well and then add sufficient water (for mixing). With acrylic paint, apply appropriately to the paper, with a gentle stroke (the paint brush has to be sharp yet flexible). For a smooth and untextured area, steadily, with a “back and forth” like gesture, paint the necessary section.
To paint neatly, use a small, sharp, brush for a precise and accurate finish. Furthermore, use high-quality acrylics/or paints, high-quality paper and two pots of clean water (so that the uncontaminated paint doesn’t become contaminated).
Additive Colours & Subtractive Colours
Additive Colour definition:
Additive colour is colour created by mixing a number of different light colours, with Red, green, and blue being the primary colours normally used in the additive colour system.
Computer monitors and televisions are the most common examples of additive colour. Examination with a sufficiently powerful magnifying lens will reveal that each pixel in CRT, LCD and most other types of colour video displays is composed of red, green and blue sub-pixels, the light from which combines in various proportions to produce all the other colours as well as white and shades of grey. The coloured sub-pixels do not overlap on the screen, but when viewed from a normal distance they overlap and blend on the eye’s retina, producing the same result as external superimposition.
Another example of additive colour can be found in the overlapping projected coloured lights often used in theatrical lighting for plays, concerts, circus shows and night clubs.
Systems of additive colour are motivated by the Young–Helmholtz theory of trichromatic colour vision, which was articulated around 1850 by Hermann von Helmholtz, based on earlier work by Thomas Young.
For his experimental work on the subject, James Clerk Maxwell is sometimes credited as being the father of additive colour. He had the photographer Thomas Sutton photograph a tartan ribbon on black-and-white film three times, first with a red, then green, then blue colour filter over the lens.
The three black-and-white images were developed and then projected onto a screen with three different projectors, each equipped with the corresponding red, green, or blue colour filter used to take its image.
When brought into alignment, the three images (a black-and-red image, a black-and-green image and a black-and-blue image) formed a full-colour image, thus demonstrating the principles of additive colour.
Subtractive Colour definition:
Subtractive colour mixing is the kind of mixing you get if you illuminate coloured filters with white light from behind. The commonly used subtractive primary colours are cyan, magenta and yellow, and if you overlap all three in effectively, equal mixture, all the light is subtracted giving black.
If the incident light is other than white, our visual mechanisms are able to compensate well, but not perfectly, often giving a flawed impression of the “true” colour of the surface.
The RYB primary colours became the foundation of 18th-century theories of colour vision. These theories were enhanced by 18th-century investigations of a variety of purely psychological colour effects, in particular, the contrast between “complementary” or opposing hues produced by colour afterimages and in the contrasting shadows in coloured light.
These ideas and many personal colour observations were summarised in two founding documents in colour theory: the Theory of Colours (1810) by the German poet and government minister Johann Wolfgang von Goethe and The Law of Simultaneous Colour Contrast (1839) by the French industrial chemist Michel-Eugène Chevreul.
In late 19th and early to mid-20th-century commercial printing, use of the traditional RYB terminology persisted even though the more versatile CMY (Cyan, Magenta, Yellow) triad had been adopted, with the cyan sometimes referred to as “process blue” and the magenta as “process red”.