What is light? What is color?

What is light? What is color?

There can be few people today, who don’t have some idea of what radiation is, or have not heard the terms electromagnetic radiation and wavelength. Light is simply electromagnetic radiation of certain wavelengths visible to the eye. Light is thought of as rays that can travel in straight lines although these rays can be reflected, refracted, absorbed, or transmitted when in contact with other media.

Strictly speaking, only radiation capable of affecting the eye to produce visual stimulation should be referred to as light. The word ‘light’ is used in photography however, to include other wavelengths of radiation that can affect photographic materials.

Both the eye and photographic materials work on the principle of sensitivity to the three primary colors. The visible color spectrum can be thought of as containing three bands: blue, green, and red - the primary colors. Mixing red, Green and blue can represent all colors. This is also the way that monitors display color.

Common Terms...

CMS - Color Management System. A software program (or a software and hardware combination) designed to ensure color matching and calibration between video or computer monitors and any form of hard copy output.

Color Balance - The accuracy with which the colors captured in the image match the original scene.

Saturation - The degree to which a color is undiluted by white light. If a color is 100 percent saturated, it contains no white light. If a color has no saturation, it is a shade of gray.

Channel - One piece of information stored with an image. True color images, for instance, have three channels-red, green and blue.

Chroma - The color of an image element (pixel). Chroma is made up of saturation + hue values, but separate from the luminance value.

Color Correction - The process of correcting or enhancing the color of an image.

Diffusion Dithering - A method of dithering that randomly distributes pixels instead of using a set pattern.

Dithering - A method for simulating many colors or shades of gray with only a few. A limited number of same-colored pixels located close together is seen as a new color.

Continuous Tone - An image where brightness appears consistent and uninterrupted. Each pixel in a continuous tone image file uses at least one byte each for its red, green, and blue values. This permits 256 density levels per color or more than 16 million mixture colors.

Color Depth - Digital images can approximate color realism, but how they do so is referred to as color depth, pixel-depth, or bit depth. Modern computer displays use 24-bit True Color. It's called this because it displays 16 million colors, about the same number as the human eye can discern.
True Color - Color that has a depth of 24-bits per pixel and a total of 16.7 million colors.
Palette - A thumbnail of all available colors to a computer or devices. The palette allows the user to chose which colors are available for the computer to display. The more colors the larger the data and the more processing time required to display your images. If the system uses 24-bit color, then over 16.7 million colors are included in the palette.
Hue - A term used to describe the entire range of colors of the spectrum; hue is the component that determines just what color you are using. In gradients, when you use a color model in which hue is a component, you can create rainbow effects.