Thursday, 24 November 2011

Colour Theory

Colour Theory Lecture 1
There are two different types of colour additive and subtractive colour. 
Addictive colour
An additive color model involves light emitted directly from a source or illuminant of some sort. The additive reproduction process usually uses red, green and blue light to produce the other colors. Combining one of these additive primary colors with another in equal amounts produces the additive secondary colors cyan, magenta, and yellow. Combining all three primary lights (colors) in equal intensities produces white.
Additive color systems start without light (black). Light sources of various wavelengths combine to make a color. In either type of system, three primary colors are combined to stimulate humans’ trichromatic color vision, sensed by the three types of cone cells in the eye, giving an apparently full range.


RGB colour is obviously to do with light, and is based around the concept of white, and the colours that make up light waves. i.e. white. Isaac Newton back in the day found this out when he shined light through a prism and it split up the light into three principle colours: red, green and blue.
RGB colour is mainly based around screen, projectors, cameras, pixel based tools such as computer monitors. This is why RGB is used for web, so whatever colour you work with, it will display how it should and the colour won't change drastically. Similarly you should never work with CMYK colour modes, to produce work that will be displayed on the web. The different colour resolutions and colour modes of different monitors will make the colours work out differently.

Subtractive Colour
A subtractive color model explains the mixing of paints, dyes, inks, and natural colorants to create a full range of colors, each caused by subtracting (that is, absorbing) some wavelengths of light and reflecting the others. The color that a surface displays depends on which colors of the electromagnetic spectrum are reflected by it and therefore made visible.
Subtractive color systems start with light, presumably white light. Colored inks, paints, or filters between the viewer and the light source or reflective surface subtract wavelengths from the light, giving it color. 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" color of the surface.


CMYK is mainly to deal with print - offset printing, paints, plastics, fabrics, and photographic prints are all based on CMYK colour. Basically anything that comes out of a printer is CMYK colour. Most printers have seperate ink cartridges for C, M, Y and K. and mix them together to make pretty much any colour possible.
CMYK colour is where Cyan (C), Magenta (M), Yellow (Y) mix together to form Black (K). Sometimes called Key, or Kblack.

Other terms:
Primary Colors: This definition really depends on what type of medium of color we are using. The colors that are seen when sunlight is split by a prism are sometimes called the spectral colors. These are red, orange, yellow, green, blue, indigo, and violet. These ROYGBIV colors are often reduced to three "red, green, and blue-violet" which are the primary colors for the additive color system (light). The primary colors for the subtractive color system (paint/pigment) are "cyan, magenta and yellow." Notice that "red, yellow and blue" should never be used as the combination for color primaries!
Secondary colours result from the mixing of two of the primary colours. Red (magenta) and yellow produce orange, yellow and blue (cyan) produce green while red and blue (cyan) produce violet. For example, if you add more red than yellow, you get a reddish orange, and if you add more yellow than red, you get a yellowish orange.
Tertiary colors are browns and grays, containing all three primary colors. They're created by mixing either all three primary colors or a primary and secondary color (secondary colors of course being made from two primaries). By varying the proportions of each primary color, you create the different tertiary colors.

Colours that are opposite one another in the chromatic circle are called complementary. For example, green (resulting from the mixing the primary colours yellow and blue [cyan]) is complementary to red. Orange (a mixture of yellow and red [magenta]) is complementary to blue, while violet (a mixture of blue [cyan] and red [magenta] is complementary to yellow.

Chromatic Value: 
When we describe a color as "light" or "dark", we are discussing its chromaticvalue or "brightness". This property of color tells us how light or dark a color is based on how close it is to white. For instance, canary yellow would be considered lighter than navy blue which in turn is lighter than black. Therefore, the value of canary yellow is higher than navy blue and black.
This is what we usually mean when we ask "what color is that?" The property of color that we are actually asking about is "hue". For example, when we talk about colors that are red, yellow, green, and blue, we are talking about hue. Different hues are caused by different wavelengths of light. 
Think about a color's "purity" when describing its "chromaticity" or "CHROMA". This property of color tells us how pure a hue is. That means there is no white, black, or gray present in a color that has high chroma. These colors will appear very vivid and well, ... pure. This concept is related to and often confused with saturation. However, we will continue to use these terms separately because they refer to distinct situations, as explained here.
Related to chromatic value, saturation tells us how a color looks under certain lighting conditions. For instance, a room painted a solid color will appear different at night than in daylight. Over the course of the day, although the color is the same, the saturation changes. This property of color can also be called intensity. Be careful not to think about SATURATION in terms of light and dark but rather in terms of pale or weak and pure or strong.

Tints, Tones and Shades: 
These terms are often used inappropriately but they describe fairly simple color concepts. The important thing to remember is how the color varies from its original hue. If white is added to a color, the lighter version is called a "tint". If the color is made darker by adding black, the result is called a "shade". And if gray is added, each gradation gives you a different "tone."

From looking at all this terminology we made our own colour wheel out of objects we brought in.

Colour Theory Lecture 2

After the first lecture of colour where we looked at the basics of colour, we started to go more in depth and look at colour even more. We were introduced into Itten's 7 contrasts of colour.

Contrast of Tone: Formed by the juxtaposition of light and dark values.
Contrast of Hue: Juxtaposition of different hues, the greater distance between hues on colour wheel the greater contrast between the two colours
Contrast of Saturation: Light and dark values and their relative saturations
Contrast of Extension: Assigning proportional field sizes in relation to visual weight of colour
Contrast of Temperature: Hues that can be considered warm and cool
Complementary Contrast: complementary colours from a colour wheel or perceptual opposites
Simultaneous Contrast: Boundaries between colours perceptually vibrate

From learning these contrasts we did an investigation into each of the contrasts.

Colour Lecture 3
In this lecture we continued to investigate into colour and how changed the background colours etc can effect how the colour is perceived.

No comments:

Post a Comment