Physics/Science of Light (PART 3)
Light and Surface Colour
(How you could implement it + create dramatic compelling art scenes)
When light and surface colour interact our eyes view this process and a signal is created; this signal then travels to our brains.This allows the opportunity for our brains to interpret the relationship and processes occurring between the two components.
A wavelength is energy, a quantum property of the photon of light. There are different wave lengths of light and in science they use nanometers to measure the distance between the peaks and troughs that are present in wavelengths. You don't have to necessarily understand this topic thoroughly but to understand that different wavelengths exist as well as how it affects the attributes and properties that cause light as a whole to behave should be rudimentary.
If we have green photons, (green coloured photons) and they are hitting an object that isn't green, (such as a black object) what happens in this interaction is that the light which hits the surface of the black object cause the black atoms (that make up the surface) to vibrate.
This occurs due to absorption resonance frequency for each atom/molecule. When a certain wavelength hits an atom it makes it vibrate. The wavelength (energy) gets absorbed by the molecule or atom,
and re-emitted as heat which causes the energy of the light and the visible properties of light to be lost in this particular circumstance.
If on the other hand, we have an atom that is green (or a molecule that is green) and a wavelength that is red or purple, the red and purple wavelengths get absorbed by the green atoms. It then gets repelled as heat (the same way a black atom/molecule does except the green atom is being repelled).The results that are produced from this interaction eventually meets our eyes and allows us to see green objects.
Keep in mind that our experience with light and colour is not completely scientific, our own interpretations/perceptions of the world is part of the process, so there really isn't an exact way to interpret these types of circumstances.
Most atoms/molecules (or surfaces/materials) aren't made up of one pure colour. For instance, if we have a surface made up of purely saturated green coloured molecules, this type of surface isn't just emitting green wavelengths, in fact, it is emitting a multitude of colours. Most surfaces are made up of different coloured wavelengths but there will always be one dominant colour. This dominant colour surpasses the other colours in strength and vibrancy; which will cause the surface to become that dominant colour.
There are cases in which you may have only one pure colour in an object but most cases, we don't have completely pure colours.
Local Colour: is the true colour of a surface (without being affected by different lighting schemes; which shift the saturation, tint or value of the original colour).
For example if you examine your skin tone under a white or florescent light you'll recognize that your skin's tint doesn't change much under this circumstance. Whereas if you examine your skin colour under a red orange light (during sunset or the "golden hour") you can expect to see your skin's tint shift to more orange.
Properties of Light: Colour
Light has properties of both a wave and a particle. When discussing colour, the wave properties are most important.
The colour of light has a different wavelength. The longest wavelengths are on the red end of the colour spectrum, and the shortest towards the blue and violet.
White light is made out of all the colours of the rainbow, in fact what happens in the rainbow, prism, or raindrops, is that they actually split the light into its constituent parts. All the wavelengths that make it up actually spread out. Whereas when all the coloured wavelengths are compressed-we see it as white light.
As this white light is striking an object, (the blue object as shown above) what happens is most of the wavelengths in the white light are absorbed (by the object on the right) and emitted as heat.
The particles that are not re-emitted but instead reflected out from the surface cause us to see that apparent colour of the surface. This is very dependent upon the properties of the light, for instance, if it's pure white light we will see most of the local colour of the object. However most light is not pure white.
When white light strikes a surface, most of the light is absorbed and converted into heat. However, some wavelengths are reflected and we see those as the colour of the object.
Light and Surface Colour:
Without light, a "local colour" doesn't exist- there is only the reaction of the surface to light.
Essentially, without any light, there won't be a colour to the surface. The surface properties that make an object visible to us as red (or any other colour) is built in the DNA of the object's molecules. The determinative factor that allows the surface to appear a certain colour is greatly dependent on the light it is interacting with.
Here's an example of a surface that is red, it is red under a pure white light.Local colour is only visible because a material absorbs every color except for a small part of the spectrum.
Different coloured lights cause less light to be reflected and what light does reflect is a combination of the light and local colours. As soon as we put the object under a yellow light, we actually lose some of the red characteristic, and there's two things that happen:
1. we lose value
2. we lose a bit of the saturation.
Lights farther away on the spectrum from the surface colour (like complimentary objects) reflect very little light.
If the colour of the light is fairly close on the spectrum to the local colour of the object, we won't lose a whole amount of value or saturation.
If your skeptical, you can always experiment and make observations yourself which will enable you to really grasp the science. Set up an experiment in your house using a LAD coloured light through coloured filters and record what happens to an object when different colours of light interact with it.