Data Representation

Note of Computer Networks!! Information today comes in different forms such as text, numbers, images, audio and video. Brief description about each of them is given below: Video: Video is the another form of the data that is transmitted over the computer networks. It refers to the recording or broadcasting of the pictures or videos. Video can either be produced as a continuous entity (e.g., by a TV camera), or it can be combination of the images, each a discrete entity, arranged to convey the idea or motion. We can change the video to a digital or an analog signal. Text: In data communications, text is represented as a bit pattern, that is a sequence of bits (either 0s or 1s). Different sets of bit patterns have been designed to represent text symbols. Each set is called a code, and the process of representing symbols is called coding. Today, the most prevalent coding system is called Unicode, which uses 32-bits to represent a symbol or character used in any language in the world. The American Standard Code for Information Interchange (ASCII), developed some few decades ago in the United States, now constitutes the first 127 characters in Unicode and is also referred to as Basic Latin. Numbers: Numbers are also represented by bit patterns. Unlike a text, to represent numbers does not require a code such as ASCII. The number is directly converted to a binary number to simplify mathematical operations. Images: Images are also represented by bit patterns. In its very simplest form, an image is composed of a matrix of pixels (picture elements), where each pixel is a small dot. The size of the pixel depends on the resolution. For example, an image can be divided into 100 pixels or 1,000 pixels. In previous example, in second case, there is a better representation of the image (i.e, better resolution), but the memory usage of the computer is increased to store the image. After an image is divided into pixels, each pixel is assigned a bit pattern. The size and the value of the pattern depend on the image. For an image made of only black-and-white dots (e.g., a chessboard), a 1-bit pattern is enough to represent a pixel. To represent four level of gray scale, 2 bit-patterns can be used. A black pixel can be represented by 00, a dark gray pixel by 01, a light gray pixel by a 10, and a white pixel by 11.  There are several methods to represent color images. One method is called RGB, so called because each color is made of a combination of three primary colors; red, green, and blue. The intensity of each color is measured, and a bit pattern is assigned to it. Another method is called YCM, in which a color is made of a combination of three primary colors: yellow, cyan, and magenta. Audio: Audio is the another form of the data that is to be communicated. It refers to the exchange of the recordings or broadcasting of sound or music. Audio is by nature different from text, numbers, or images. Unlike text, numbers and images it is continuous. Even when we use a microphone to change voice or mute to an electric signal, we create a continuous signal. Video: Video is the another form of the data which is transmitted over the computer networks. It refers to the recording or broadcasting of a pictures or movie. Video can either be produced as a continuous entity (e.g., by a TV camera), or it can be a combination of the images, each a discrete entity, arranged to convey the idea of motion. We can change the video to a digital signal or an analog signal.