Color depth is a reference to how many colors a computer screen can display, based on the number of bits per pixel. A color depth of eight bits, for example, yields 256 colors. The color depth rises exponentially as bits are added, allowing people to see more accurately colored and detailed images. Many computers allow people to choose between several color depths for color display. Along with other graphics qualities like resolution, this will influence the final display appearance of images on screen.
A single bit per pixel offers two colors. The pixel can either be on or off, creating one or two colors. Black and white are common, although some computers once operated with black and green. Adding another bit creates the possibility of four colors, as each bit can be toggled on and off to create more layers of color. As bits are added, more colors become possible through eight-, 16-, and 24-bit color. Twenty four-bit color, yielding 16,777,216 colors, is sometimes called “true color,” a reference to the accuracy of shading and hue available.
With high color depth values, color can be quite distinct and detailed. Computers can use a number of systems for displaying color, including the red, green, blue (RBG) system, where colors are expressed in values of red, green, and blue. Cyan, magenta, yellow, and key or black (CMYK) color display is also available on some computers and may be used by graphic designers preparing images for press, as press operators usually use CMYK color coding when mixing colors for print runs. Hexadecimal identification may be used as well.
High color depth is not always necessary. For something like word processing, only two colors are absolutely needed, while additional colors can be helpful for easing eye strain and offering functionality like using highlighting, different text colors, and so forth. Image processing, on the other hand, requires a high color depth when people are working with things like color photographs.
It is important to be aware that color depth is controlled by the screen settings, not the image itself. A person can save an image in 24-bit color and send it to a person with an eight-bit monitor, and the other person will only see 256 colors, no matter how many colors there are in the original image. Image quality can also be influenced by other factors involved in the process of saving and processing the image. For things like preparing images for display on the web, people must consider quality issues to make sure images display as best as possible in all possible browsers. Extremely subtle color variations may not be visible in all browsers, leading to decreased comprehension and enjoyment on the part of web users.