Light’s Energy and Standard Colors

 

Here is a pure beam of light having a specific frequency. This beam of light is created when the electron inside an atom transitions from a high energy level to a low level, as the difference between the two energy levels is emitted as light. Lights in the visible spectrum are in fact electromagnetic waves, and each has its corresponding photon energy. The amount of the photon energy is calculated by multiplying the light’s frequency with the Planck constant. The frequency of a light is inversely proportional to the wavelength; the shorter the wavelength, the higher the frequency, and the color closer to purple.

 

A human eye has three types of cone cells. In the visible spectrum (wavelengths 380nm to 780nm), the L (long) cone senses red lights which have long wavelengths, the M (medium) cone senses green lights of medium wavelengths, and the S (short) cone senses blue lights of short wavelengths. Each sensed signal is marked as LMS or R, G, B (red, green, blue). However, the LMS signals are not sent directly to the brain; instead, the signals interact and merge in the retina to create three channels: the A channel is the sum of all LMS signals, the R-G channel is M subtracted from the sum of L+S, and the Y-B channel is S subtracted from the sum of L+M.R, G, B signals from cone cells interact and merge in this process to create another color, Y (yellow). By combining these four types of color information, humans can see all the existing colors of the world.

 

The result of the abovementioned process is highly complicated in that it lets humans see every existing shade of colors, but the mechanism behind human color recognition is parsimoniously simple. If just a few types of cone cells can let humans enjoy all hues of the world, and likewise if the standard colors can be identified, wouldn’t it also be possible to create countless colors from just a handful of paint tubes? This question urged me to measure the color of artists’ paints with a spectrophotometer and find standard colors by analyzing the results.

 

What we call as a color is, in fact, a result, the end outcome of the process through which the human body recognizes a radiation in the visible spectrum. Hence, there exist various definitions for standard colors even though each definition is intended to serve as the criterion for measurement. An object color, in full detail, is the process of sensing a color which reflects light, but as each human body is unique and slightly different from each other, and as each region of the world has different environments (for instance, the amount and angle of sunlight), there are no globally-agreed standard colors. Here is an example: a country’s government must decide public design color standards which can be used throughout various administrative areas, and the color ‘red’ defined by each standard is slightly different from one another. However, an unspoken agreement defines standard colors for daily life purposes.

 

Colors in the visible spectrum move gradually from magenta → blue → cyan → green → yellow → red depending on the energy it possesses, similar to the HSB color model. HSB stands for hue, saturation, and brightness. Hue is represented by degrees of the circle, where 0° is red (R), 60° is yellow (Y), 120° is green (G), 180° is cyan (C), 240° is blue (B), and 300° is magenta (M). Therefore, in the language of physics, HSB can be interpreted as thus:

 

- Hue (H) is inversely proportional to the wavelength of visible spectrum lights(small H values for longer wavelengths, and large H values for shorter wavelengths).
- Saturation (S) measures the purity of light, in the sense that the designated light is not tinted with lights of other 
wavelengths.
- Brightness (B) is the amount of light.

 

Finding standard colors from manufactured paints was not easy. Some paints were nearly identical to the primary colors in terms of the hue, but low saturation and brightness made these paints look nothing like primaries. Whereas, other paints had high saturation and brightness but did not satisfy the hue requirements. In some cases, making a decision was hard because the difference was too minute. Therefore, I created an equation for identifying standard colors. Using the measurement data, this equation can identify paints nearest to the standard colors. However, this equation is restricted to my artworks and may be progressively modified in the future.

 

▶ Measure the HSB values of a paint with a spectrophotometer, and identify six paints which are closest to the hue angles 0°, 60°, 120°, 180°, 240°, and 300°. However, the sum of saturation and brightness must exceed 140.

 

Six paints were identified through this experiment. Jo Sonja’s Artists’ Colours were used in this experiment, and from Jo Sonja’s catalog, the following six paints met the criteria: Napthol Red Light (RED), Cadmium Yellow Light (YELLOW), Brilliant Green (GREEN), Aqua (CYAN), Ultramarine Blue Deep (BLUE),and Brilliant Magenta (MAGENTA).Paints Titanium White (WHITE) and Carbon Black (BLACK) were added to the six, completing the set of eight standard colors.

 

Now that the standard colors have been found, it is time to conduct color mixing experiments. First, specimens are made by weighing each paint in proportion to the color mixture ratio. Afterward, each mixed color is measured with a spectrophotometer, and the data is analyzed. This ongoing experiment ultimately aims to create a method which can create thousands of colors just by using the standard colors.