Visible Light Spectrum

Summary

The visible light spectrum is a part of the electromagnetic spectrum that we can see. It is the range of wavelengths called visible light. The longest wavelength is red, whereas the shortest is blue. Light plays a significant role in how our eyes perceive color. In photography, A color rendering index (C.R.I.) is a quantitative measure of the ability of a light source to faithfully reveal the colors of various objects compared to an ideal or natural light source. It is essential to know how the light source affects the colors in an image

The Science of Vision and Light

A photographic image is produced by capturing a variety of different types of lights. Each light ray is reflected in various parts of a scene. Dark objects absorb more light than lighter objects. The light reflects into the lens and is focused onto the camera's sensor producing an image. But what is light?

Light is a type of radiant energy wave that we can visually perceive with our eyes. Visible light is a small part of a large part of what is called the Electromagnetic Spectrum, which contains all the energy types that travel through space in a wave-like manner. Every day, light waves reflect off objects and into our eyes, which allows us to see the objects. Click learn more to open the diagram of the electromagnetic spectrum.

The Science of Color and Light

To better explain how our eyes see color, imagine a green apple. Why does the apple appear green? The light shines onto the apple, causing the apple to absorb every color in the spectrum besides green. The color that the apple does not absorb is reflected in our eyes, causing us to see green. Light is just a minor fraction of the entire Electromagnetic Spectrum. Within that small area lie all the colors that we can see called the visible spectrum.

All the colors have different wavelengths that make them the colors that they appear. For example, red color waves are very long, while blue color waves are very short. Colors are also associated with temperature or the way that the colors are perceived. Red is perceived as a warm color due to the psychological impact red has on our brains. Typically, warm objects are red, like a heating stovetop or a red flame.

Light plays a significant role in how our eyes perceive color. The source of the light determines how our eyes see the color. For instance, if we view a Green hat outside in the sunlight and then take it inside to look at it under a lamp, it may appear a darker shade due to the change in the Color Rendering Index, or how light makes colors appear. A color rendering index (C.R.I.) is a quantitative measure of a light source's ability to reveal the colors of various objects faithfully in comparison with an ideal or natural light source. The below diagram shows how an apple will appear in different types of light.

color rendering index

Lighting metrics are used to describe, understand, and predict how a light energy source will operate. Three components make up lighting metrics: the quantity of light, quality of light, and efficiency of light. Quantity of light must deal with the levels of light that a source puts out, or the amount of light that leaves an object. This quantity is measured in lumens.

Quality of light refers to the brightness and color of light emitted from an object, such as a ceiling fan with lights. Depending on the brightness of an object, glare may be produced. There are two types of glare, direct and reflected. Direct glare comes directly from a light source and hinders visibility. Reflected glare occurs when a light source reflects off an object and causes a glare.

Types of glare