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Color - From Theory To Practice

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I am proud to introduce you to my dear Brazilian friend, Ana Lúcia Heringer. She is a singer, artist and author. Her practical knowledge about color was obtained during a period of more than eight years devoted to the manufacture of silk dyes. Through much study and research pertaining to silk dyes, her curiosity regarding color blossomed into an abundance of knowledge. This is the introductory chapter of her book, entitled "Da Teoria à Prática Da Cor" or "Color - From Theory to Practice". It will be published in both Portuguese and English.

Ana Lúcia Heringer



THE COLOR

What is color? Many scientists, mathematicians, and physicists, among others, have searched for this answer throughout the history of mankind. Today, we know that color is light and light is color.

Colors do not belong to objects, or nature, they belong to the light that illuminates them, be it natural or artificial. This affirmation is simple to prove with the answer of only one, simple question:

- Is it possible to define the color of some object when it is placed in the dark?

The answer to this question is, certainly, ‘NO’. The object needs the light to make its color seen, perceived. If the color of the object belonged to the object itself, the object would always present the same coloration, under any light conditions, isn’t that so?


HOW THE COLOR IS PROCESSED IN OUR EYES

The eye is an optical organ capable of perceiving the physical elements of light. The incidence of photons on the optical nerve inside our ocular globe produces an electric reaction that is sent to the brain where, finally, a response occurs which makes us perceive the color.

Because color is interpreted in the brain, color is a sensation, something subjective, the final result of an involved process. And this subjective interpretation brings up another aspect of this process: Nobody sees the same color in the same way. Each person sees color according to the interpretations that were made by his/her brain in an individual and personal way. Isn’t that great? The colors you see are seen only by you and nobody else in the world.



1- Iris: The colored part of the eye located between the Lens and Cornea. It regulates the entrance of the light.

2- Cornea: The transparent, blood free tissue covering the front of the eye that initially refracts or bends light rays as light enters the eye.

3- Retina: The innermost layer of the eye, a neurological tissue, which receives light rays focused on it by the Lens. This tissue contains receptor cells (Rod and Cones).


4- Rods: The receptor cells which are sensitive to light and located in the Retina of the eye. They are responsible for night vision and non-color vision in low level light.

5- Cones: The receptor cells which are sensitive to light and located in the Retina of the eye. They are responsible for color vision.

6- Lens: The eye's natural lens. A transparent, biconvex interocular tissue that helps focus rays of light on the Retina.

7- Pupil: The opening at the center of the Iris. It contracts in high light levels and when the eye is focused on distant objects.

As you can see, the eye is well designed to receive the elements of light and color.



LETS TAKE A CLOSER LOOK AT CONES AND RODS




·CONES: These are the cells responsible for the perception of colors. To be capable of transmitting information about colors, objects must be in well illuminated environments. As the intensity of the light decreases, cones slowly lose their capacity to transmit color information to the brain.





·RODS: The simplest vision is processed through the rod cells. They work in low light levels and are capable of defining the contours of objects by the contrast between light and dark, long after the cones have lost their ability to distinguish colors. For example, if we keep our eyes open after turning off the light in a room, we will be able to make out the shapes in the room thanks to the rods.


HOW WE PERCEIVE COLOR

Our color perception is made possible through the process of reflection and absorption of light waves on a surface. When a light ray penetrates into a surface, this surface will absorb part of the colors of the light and it will reflect either a specific color, or mixture of colors. This separation of light waves occurs from the different ways in which each surface reacts to waves of light.





The molecular composition and arrangement of objects differs one from another and this difference is what provides the capacity that each object has to separate the colors. For instance, when we see a green grass the process that makes us see that particular green is the following:

-It absorbs (subtracts, removes) all colors but Yellow and Blue. Then it reflects (shows, makes visible) a mixture made between these colors: Yellow + Blue = Green.

This green will be seen as a dark, medium or light green, depending on the ratio of Blue and Yellow that this particular grass reflects and also on the light conditions the grass was under at that exact moment. This process happens with everything around us.


THE WHITE COLOR

A surface will be White when it does not absorb any colors and reflects all colors at once. White is a result of the light being reflected in all color wave lengths, simultaneously. It is the mixture of all colors. It is recomposed light. If we think of light as composed of all colors we will conclude that any color other than White is ‘dissociated light’, ‘broken light’, ‘divided light’ and – therefore - we will conclude that the White is the integral colors of the light.

When all color waves are reflected at the same time and none is absorbed, this is nothing more than the process of ‘resetting’ the light to its natural form, to make it go back to being White. But, if we had perfect vision, with enough resources for the analysis of the differences, we would not see White. Instead, we would see a light with an infinite number of colors. With perfect vision we could accurately testify every day, in everything around us, the color phenomenon; the process that everything in the world uses to become colored when illuminated. But since we are not capable of dissociating the light with the optical resources we have, we are only able to see White light, which is, in reality, a tumult, a confusion that we are used to seeing. However, honestly, I’m thankful for this - (laughs).




THE BLACK COLOR

On the other hand, a surface will be Black when it absorbs all colors and reflects none. In fact, it is a subjective mechanism of our vision because there is nothing referring to the light with this color. The Black color is, in other words, the total absence of light and, therefore, the total absence of colors. In this context, the Black and White colors are not colors because the first one hides all colors and the second ‘shuffles’ them, tricking our eyes to perceive it as White. We can say that colors are found between these two extremities and both (Black and White colors) can be considered as being achromatic colors, which means ‘colors with no color’. The resultant Grays of mixtures made between the White and the Black colors can also be classified in this same category.




WAVE LENGTH


Waves of colored light have different lengths among themselves. We are capable of perceiving the Red first because it has the longest wave, reaching our cones before the others. Another phenomenon occurs in relation to Red in that it is focused behind the retina, making our eye's lenses a little more convex. Because of this, the color Red seems to be ‘bigger’ than the other colors, giving us the sensation that it is projecting itself towards us.

The Blue(s) and Violet waves are the shortest ones and, therefore, they are the last ones to reach our cones. These Blue colors are focused in the front of the retina compelling our eye's lenses to be a little less convex. This gives us the impression, the sensation, that they are more distant, seem to retrocede and, also, seem to be ‘smaller’. There are two colors in the specter (the total set of the colors) that our eyes are not capable of perceiving, or of seeing. These are the infra-red and the ultraviolet rays.



If we use our alphabet to define the Light wavelengths, we would have something like the graphic above. The letter “a” corresponds to the Red and it is 740 nm (*nanometer), being the longest of all. The letter “z” would be the Violet, which is 400 nm, the shortest of all. All the other specter colors possess intermediate values between these two (740nm and 400nm). The closer to the Red the longer the wave will be and, obviously, the closer to Violet the shorter it will be.

* Nanometers: Measure of Light. There is a billion nanometers in a meter.

We can say that this is the basic technical information about color. The subjects we touched on have enough material to produce several other books. However, this basic knowledge is enough to understand the color ‘mechanisms’ and its deep and unseparable relation with the light.

Author - Ana Lúcia Heringer
Editor - Jim Stevens


More Tips:
Introduction Page | Optical Mixing | Translucent Water | Color Contrasts
Technical Tips | Hue, Value, Intensity, Color Temperature | Composition
Red Power | Keeping Acrylics Moist | Brush Care | Young/Helmholtz | Book Excerpt


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