A pixel's color is stored by a computer as a set of three numbers: the quantity of red, green, and blue that determines the color of that pixel. So there you have it: every color inside a computer is reduced to a set of three digits. Color is seen by the human eye via three receptors. The computer only has two types of sensors, so it has to make some assumptions about what color something is.
When you view images on a screen, your computer simply sends an electrical signal to your monitor indicating that this particular pixel should be turned on. It is up to the monitor to decide how to implement this command. Most monitors use a technology called "dot matrix" printing to create an image on their surface. Each pixel is represented by one dot in a grid. By turning on or off different dots, the printer can determine which pixels should be illuminated and which shouldn't. This is done electronically; no physical light source is used.
The quality of your monitor affects not only the appearance of printed images but also their performance reliability. For example, a glossy display reflects light from outside sources back into your eyes when viewed from an angle, which may cause glare. A matte display does not reflect light, so it appears less reflective and tends to reduce eye strain.
There are several types of colors available for storing on a computer.
A monitor or television screen emits three colors of light (red, green, and blue), and the many colors we see are the result of varying combinations and intensities of these three fundamental colors. Each pixel on a computer screen is made up of three little dots of phosphor compounds surrounded by a black mask. When these pixels are activated by an electronic signal, they emit one of the three primary colors, depending on which bit in the signal is most positive.
The shape of the mask around each dot determines what part of the spectrum it will emit. A round mask gives more red, a square mask gives more green, and a line-shaped mask gives more blue. By combining these three parts of the spectrum, any color can be produced. For example, consider the color white. It is the combination of all three primaries: red, green, and blue. If you increase the intensity of one component while reducing the others, then new colors can be generated. For example, if you double the strength of the red component, then you get magenta (which is half red, half blue). If you quadruple the strength of the red component, then you get cyan (which is quarter red, quarter blue). There are other colors between magenta and cyan that can be generated in this way.
To create realistic images, computers also use components with different levels of brightness. This is usually done using filters that block out certain frequencies of light.
The computer display, like a television, employs small dots (pixels) that change color. These dots alternate between red, green, and blue. They combine in various ways to produce various hues. RGB combines colors to create new visuals. This process is the same for computers as it is for TVs.
Colors on your monitor may not be what you think they are. Monitors usually use white light from the environment or a built-in lamp to display colors. So when light hits the screen, some of it is reflected back into the eye; the rest passes through. The amount that gets reflected varies depending on how dark or light the area behind the screen is. Thus, darker areas appear blacker and lighter areas appear brighter.
This process is different from how we see in the real world where everything appears bright all around. When looking at a scene, our eyes adjust to the fact that most of the time, only part of the image is visible. For example, when driving at night, we see objects that are far away more clearly than those closer by because there's less light falling on them. Similarly, when viewing pixels on a monitor, the intensity controls the distance that things appear from it. Pixels near the edge of the screen are hit with more light than those in the middle and thus appear brighter.
No matter what color depth or hue is presented on the screen, combinations of red, blue, and green are the only colors present in the pixels. All of the other colors are created by combining these three colors in varied strengths. For example, yellow = red + green, cyan = blue + green, magenta = red + blue, white = red + blue + green.
When creating images on a computer, it is necessary to specify which colors should be rendered in which pixels. An image program will divide up the colors it needs from you based on their definitions in the palette (which can be modified with custom colors). For example, if you wanted to create an image that was mostly black and white, but with some red lines running through it, you would first need to define your colors. A color is defined by its RGB value: red, green, blue. So, to create a color with RGB values of 128, 0, 255, for example, type "black" into the color name field and press enter. Do the same thing to create a color with RGB values of 0, 255, 0. That's all there is to it! Colors are very easy to modify once they're defined this way; simply change any one of the R, G, or B values and click OK to update the color.
Now, let's move on to images.
The RGB additive color model is used to generate light from computer displays. Three main colors—red, green, and blue—are blended together in this scheme to generate the many hues of color that humans experience. The secondary additive colors, cyan, magenta, and yellow, are a combination of the three fundamental colors.
In digital photography, these same three primary colors are used to create all other colors by adding different amounts of each component. For example, red can be added to black to create white; green can be added to blue to create purple; and yellow can be added to the mixture of red and green to create orange.
Computer monitors work on similar principles but use liquid crystals instead of glass filters to combine the three primaries. This allows for greater resolution than could be achieved with traditional monitors. Digital cameras also use red, green, and blue filters to separate light into its components. However, they do not have to be combined again before being projected onto a screen or inserted into a photo film packet.
The RGB color model is not unique to computers. It is also used by televisions, video cameras, and most color photographic systems. However, not all color photographic systems use all three additives. Some use two (such as blue and green) or even just one (such as red).