Most colours do not originate directly from a light source. They are created by an interplay of light, the human eye and colourgiving substances. Trees, flowers and fruits, human beings and animals, stones and even earth allow us to see countless colours without themselves generating light.
They exhibit colours through colourgiving substances. These substances have the property of absorbing a particular part of the spectrum and reflecting another. If we see a red object under white light, then this item contains a colourgiving substances which absorbs the yellow, orange, purple, blue and green components of the light.
Only the red component is reflected back to our eyes. And what about white, black and grey? In theory these are not colours. A white object contains a substance which does not absorb any colour in the spectrum. The whole spectrum is reflected. With black we see the opposite. No colour is reflected, all the colours in the spectrum are absorbed. Grey is somewhere between white and black. An equal quantity of each colour is reflected, the rest is absorbed. The reflected colours mix to become grey.
The lighter the grey the further in the direction of white , the more of each colour as reflected. And vice versa, ills. However, these examples are purely theoretical. In reality there are no substances which totally absorb a certain part of the spectrum and reflect a hundred percent of another.
We can illustrate this with the colour red. From the many shades of red we shall select vermilion to begin with. If we check what portion of the spectrum is reflected in this red, we find that the red portion is the main one. But we see too that all the other colours are also present, especially orange and yellow ill.
Let us now look at the pink colour magenta Here too the red portion of the spectrum again proves to be most evident. But equal ly all the other colours, notably violet and blue are also found ill. To summerize no colour is completely pure. Every colour contains traces of all other colours. The colour most evident after the principal colour, will affect the principal colour. White, black and grey too are only pure in theory.
An exactly identical amount of each colour is never reflected. We can subdivide colour-giving substances into two types: dyes and pigments. For the painter an important difference between the two is their lightfastness. Blended with paint or ink all dyes have poor to moderate lightfastness. The lightfastness of pigments varies from poor to excellent. The degree of lightfastness indicates the degree to which a colour-giving substance is affected by ultraviolet light.
Ultraviolet is a constituent of both natural daylight and artificial light. The speed at which this happens depends on the lightfastness in combination with the quantity of ultraviolet light.
Some colours fade after just a few weeks, others only after years or not all. A second difference concerns their solubility. Dyes dissolve in a liquid, pigments are insoluble. The lightfastness of dyes in paint or ink is poor to moderate. For educational uses or illustrative work lightfastness is of less importance.
An original illustra-tion has a temporary function and after publication can be stored in the dark. In the absence of light the colour does not fade. Pigments can be distinguished not only by their degree of lightfast-ness but also by other properties such as opacity, transparency and intensity of colour. Lightfastness varies from pigment to pigment. Thanks to modern techniques we are constantly able to improve the quality of pigments.
At present we have thousands of pigments to choose from. This enables us to replace traditional pigments with only moderate light-fastness by superior synthetically produced pigments.
The lightfastness of some products is indicated on tubes, labels and colour charts by means of the following symbols:. Paint with an opaque pigment will hide the ground from view when applied in a certain thickness. Paint with a transparent pigment is transparent at the same thickness.
Not every opaque pigment is equally opaque; not every transparent pigment is equally transparant. Many variations are possible, from very transparent to very opaque. Opacity and transparency as properties of pigments are only visible if no opaque filler is added to the paint. However, one example of an opaque paint is Poster Colour Gouache which is based on an opa-que filler, every colour of this type of paint becomes opaque, irrespective of what pigment has been used.
The intensity of a colour determines how much of that pigment is necessary to achieve a certain concentration of colour.
We shall take as an example two equal quantities of blue paint, each made with the same quantity of pigment. The difference is in the type of pigment: pigment A and pigment B. We then take equal quantities of the same white colour.
When mixed with an equal quantity of white paint, the mixture containing the blue with pigment A is much more concentrated darker than that containing pigment B. Pigment A is therefore has a higher tinting strength ill. In addition to the type of pigment the quantity of pigment also determines the tinting strength of a colour. Again we shall take as an example two equal quantities of blue paint. However, both are now made with the same pigment. The only difference is that more of this pigment has been include in blue C than in blue D.
When mixed with the same quantities of the same white paint, blue C gives a more intense result than blue D ill. In addition the grinding of a pigment affects the tinting strength of the paint. Pigments are ground in a medium. The finer the grinding the higher the tinting strength. There are differences between colours. Colour names such as yellow, orange, red and violet indicate the first clear differences. What happens when we go too far one way or the other?
You can always create a lighter or darker green glaze. Just mix your original formula with glazing medium, and apply the color over your original. Sheer glazes are built by using a ratio of medium to paint. Remember, the more pigment you use the less sheer the glaze will be. Glazing is an excellent way to play with the surfaces of green areas as well. Want to create a shadow? I have a few favorites of my own.
I use green-gold Golden , chromium oxide green and sap green hue as mixers. All in all, mixing greens is pretty fun. Infra-red is far more dangerous to use than the color red and should not be given for longer than fifteen minutes on any part of the body. Infra-red rays should not be given over the reproductive organs of a man or a woman, neither should they be given for more than two minutes over the liver, kidneys or bladder, because they can cause some damage.
Do not under any account give infra-red rays to the head, certainly not the eyes. The color red can be given over the liver, kidneys or bladder for three minutes without any harm whatever. Keep the color red away from the head of the patient who has had a nervous breakdown or who is highly strung in any way.
The effective shade is a deep full-bodied primary blue and this can be applied from the top of the head to the feet of most sufferers. If the complaint is high blood pressure, any kind of nervous breakdown, nervous tension in any one of its forms, blue applied for ten minutes can be beneficial.
On the other hand, if you suffer from a cold or flu, use orange color in preference to blue because you will discover, especially if you are sensitive that you are liable to get physically cold under the application of a blue light. This is caused because the high vibrations are short and quick and they manifest as cold rather than heat. From this you can see that orange and red produce heat and are therefore necessary in cases of low temperature; blue produces coldness and is therefore necessary in cases of high temperature.
Blue causes most people to relax. An application of blue color vibrations will also help people to sleep who suffer with mild insomnia. For more severe cases a low wattage dark blue light in the bedroom has, before now, proved beneficial. Violet can be used all over the body, but to apply it lower than the hips would be a waste of these wonderful vibrations, which are of high spiritual content.
So therefore I suggest that violet light is confined mainly to the forehead, the back and front of the head, the back and front of the neck and in concentrated form over the heart and between the shoulder blades for a total time of fifteen minutes. Violet tends to bring great relaxation and also like blue, can often be felt as waves of coldness. It does not stimulate basic circulation, but it does stimulate the flow of the more subtle energies throughout the psychic centres and the nervous system.
Because of this it is especially beneficial when used on the forehead and neck. All color treatments should start and end with green for ten minutes each time.
Bathe yourself or patient with a green light front and back for five minutes each side. Now this will tend to balance any imbalance which may have been brought about through the stimulation of red or the more subtle stimulations of the blues.
As green is the great balancer and harmonizer it causes many people to become very relaxed. It tends to counteract subtle energies which have built up in one nerve ganglia and causing starvation of another nerve ganglia. Start your treatment with an application of green and always finish with an application of green. Now there is another aspect of color therapy, which has to be done very carefully but which is nevertheless effective, that is the introduction of color through the eyes.
The key is to look for practical ways to make decisions about color. The bottom line is that there are no clear-cut guidelines for choosing colors for your brand.
In a study , researchers found that the relationship between brands and color hinges on the perceived appropriateness of the color being used for the particular brand. And while certain colors do broadly align with specific traits e. Additional research on color perception and color preferences shows that when it comes to shades, tints, and hues, men generally prefer bold colors while women prefer softer colors.
Also, men were more likely to select shades of colors as their favorites colors with black added , whereas women are more receptive to tints of colors colors with white added. Brands can easily work outside of gender stereotypes. When it comes to converting consumers, the secret to more sales is as simple as understanding consumer behavior and learning what your buyer wants from your business.
Additional studies have revealed that our brains prefer immediately recognizable brands , which makes color an important element when creating a brand identity. The closer approximations would be more properly: . One of the better low-cost approximations using a color range of 0— combines the two cases smoothly: .
There are a number of color distance formulae that attempt to use color spaces like HSV with the hue as a circle, placing the various colors within a three dimensional space of either a cylinder or cone, but most of these are just modifications of RGB; without accounting for differences in human color perception they will tend to be on par with a simple Euclidean metric.
Use of this term can be traced back to Hermann von Helmholtz and Ewald Hering. A good metric should take this into account in order for the notion of a " just noticeable difference " to have meaning. This formula has been succeeded by the and formulas because the CIELAB space turned out to be not as perceptually uniform as intended, especially in the saturated regions. This means that this formula rates these colors too highly as opposed to other colors. The definition was extended to address perceptual non-uniformities, while retaining the CIELAB color space, by the introduction of application-specific weights derived from an automotive paint test's tolerance data.
Since the definition did not adequately resolve the perceptual uniformity issue, the CIE refined their definition, adding five corrections:  . Named after the developing committee, their metric is called CMC l:c.For example, yellow light is seen when all blue light is removed from white light, magenta when green is removed, and cyan when red is removed. Consequently, when all three of the subtractive primary colors are combined, all of the additive primary colors are subtracted from white light, which results in black, the absence of all color.