There is a constant exchange of information flows in the world. Sources can be people, technical devices, various things, objects of inanimate and living nature. Information can be received by one object or several.
For a better data exchange, information is simultaneously encoded and processed on the transmitter side (preparing data and converting it into a form convenient for translation, processing and storage), sending and decoding on the receiver side (converting encoded data to the original form). These are interrelated tasks: the source and receiver must have similar information processing algorithms, otherwise the encoding-decoding process will be impossible. Encoding and processing of graphic and multimedia information are usually implemented on the basis of computer technology.
Encoding information on a computer
There are many ways to process data (texts, numbers, graphics, video, sound) using a computer. All information processed by the computer is presented in binary code - using the numbers 1 and 0, called bits. Technically, this method is implemented very simply: 1 - an electric signal is present, 0 - is absent. From a human point of view, such codes are inconvenient for perception - long lines of zeros and ones, which are encoded characters, are very difficult to decipher right away. But such a recording format immediately demonstrates what encoding of information is. For example, the number 8 in binary eight-bit form looks like the following bit sequence: 000001000. But what is difficult for a person is just a computer. It is easier for electronics to process many simple elements than a small number of complex ones.
Text Encoding
When we press a button on the keyboard, the computer receives a certain code of the pressed button, searches for it in the standard ASCII character table (American code for exchanging information), "understands" which button is pressed and transmits this code for further processing (for example, to display the character on the monitor ) To store the character code in binary form, 8 digits are used, so the maximum number of combinations is 256. The first 128 characters are used for control characters, numbers and Latin letters. The second half is for national symbols and pseudo-graphics.
Text Encoding
It will be easier to understand what encoding information is, for example. Consider the codes for the English symbol "C" and the Russian letter "C". Note that the characters are uppercase, and their codes are different from lowercase. The English symbol will look like 01000010, and the Russian - 11010001. The fact that for a person on the monitor screen looks the same, the computer perceives completely different things. It is also necessary to pay attention to the fact that the codes of the first 128 characters remain unchanged, and from 129 onwards different letters may correspond to one binary code, depending on the code table used. For example, decimal code 194 may correspond to the letter “b” in KOI8, “B” in CP1251, “T” in ISO, and not a single character matches this code in CP866 and Mac encodings. Therefore, when instead of Russian words, when we open the text, we see letter-symbol abracadabra, this means that such encoding of information is not suitable for us and we need to choose a different symbol converter.
Number coding
In the binary system of calculus, only two values are taken - 0 and 1. All the basic operations with binary numbers are used by a science called binary arithmetic. These actions have their own characteristics. Take, for example, the number 45 typed on the keyboard. Each digit has its own eight-digit code in the ASCII code table, so the number takes two bytes (16 bits): 5 - 01010011, 4 - 01000011. In order to use this number in calculations, it is converted according to special algorithms to the binary system of calculation in the form of an eight-digit binary number: 45 - 00101101.
Coding and processing of graphic information
In the 50s, computers, which were most often used for scientific and military purposes, first implemented a graphical display of data. Today, the visualization of information received from a computer is a common and familiar phenomenon for any person, and in those days it produced an extraordinary revolution in working with technology. Perhaps the influence of the human psyche has affected: clearly presented information is better absorbed and perceived. A big breakthrough in the development of data visualization occurred in the 80s, when the coding and processing of graphic information received a powerful development.
Analog and discrete graphics
Graphic information can be of two types: analog (pictorial canvas with continuously changing color) and discrete (picture consisting of many points of different colors). For the convenience of working with images on a computer, they are subjected to processing - spatial discretization, in which each element is assigned a specific color value in the form of an individual code. Coding and processing of graphic information is similar to working with a mosaic consisting of a large number of small fragments. Moreover, the encoding quality depends on the size of the points (the smaller the size of the element - there will be more points per unit area, the higher the quality) and the size of the palette of colors used (the more color states each point can take, respectively, carrying more information, the better the quality )
Creating and storing graphics
There are several basic image formats - vector, fractal and raster. A combination of raster and vector is considered separately - a widespread 3D multimedia graphics in our time, which represents techniques and methods for constructing three-dimensional objects in virtual space. The coding and processing of graphic and multimedia information is different for each image format.
Bitmap image
The essence of this graphic format is that the picture is divided into small colorful dots (pixels). The upper left point is the control. Encoding of graphic information always starts from the left corner of the image line by line, each pixel receives a color code. The volume of a raster image can be calculated by multiplying the number of points by the information volume of each of them (which depends on the number of color options). The higher the resolution of the monitor, the greater the number of raster lines and dots in each line, respectively, higher image quality. You can use binary code to process raster type graphic data, since the brightness of each point and its location coordinates can be represented as integers.
Vector image
The coding of graphic and multimedia information of the vector type is reduced to the fact that the graphic object is represented in the form of elementary segments and arcs. The properties of the line that is the base object are shape (straight or curved), color, thickness, and tracing (dashed or solid line). Those lines that are closed have one more property - filling with other objects or color. The position of the object is determined by the points of the beginning and end of the line and the radius of curvature of the arc. The amount of graphic information in a vector format is much smaller than a raster one, but requires special programs for viewing graphics of this type. There are also programs - vectorizers that convert raster images to vector ones.
Fractal graphics
This type of graphics, like vector graphics, is based on mathematical calculations, but the formula itself is its basic component. There is no need to store any images or objects in the computer’s memory; the picture itself is drawn only by the formula. This type of graphic is convenient to visualize not only simple regular structures, but also complex illustrations that mimic, for example, landscapes in games or emulators.
Sound waves
What is encoding information can still be demonstrated by the example of working with sound. We know that our world is filled with sounds. Since ancient times, people figured out how sounds are born - waves of compressed and rarefied air acting on the eardrum of the ear. A person can perceive waves with a frequency from 16 Hz to 20 kHz (1 Hertz - one oscillation per second). All waves whose oscillation frequencies fall into this range are called sound waves.
Sound properties
Sound characteristics are tone, timbre (color of sound, depending on the shape of the vibrations), pitch (frequency, which is determined by the frequency of vibrations per second) and volume, depending on the intensity of the vibrations. Any real sound consists of a mixture of harmonic oscillations with a fixed set of frequencies. The oscillation with the lowest frequency is called the fundamental tone, the rest - overtones. The timbre gives a special coloring to the sound - a different number of overtones inherent in this particular sound. It is by the timbre that we can recognize the voices of loved ones, distinguish the sound of musical instruments.
Sound programs
Conventionally, functional programs can be divided into several types: utility programs and drivers for sound cards that work with them at a low level, audio editors that perform various operations with sound files and apply various effects to them, software synthesizers and analog-to-digital converters ( ADC) and digital-to-analog (DAC).
Sound coding
Coding of multimedia information consists in converting the analog nature of sound to discrete for more convenient processing. The ADC receives an analog signal at the input , measures its amplitude at certain time intervals and outputs a digital sequence with data on the amplitude changes. No physical transformations occur.
The output signal is discrete, therefore, the more often the frequency of measuring the amplitude (sample), the more accurately the output signal corresponds to the input, the better the encoding and processing of multimedia information. A sample is also called an ordered sequence of digital data received through the ADC. The process itself is called sampling, in Russian - discretization.
The inverse conversion occurs using the DAC: on the basis of the digital data received at the input at certain points in time, an electrical signal of the required amplitude is generated.
Sample Options
The main parameters of sampling are not only the measurement frequency, but also the bit depth - the accuracy of measuring the change in amplitude for each sample. The more accurately the signal amplitude is transmitted during digitization during each unit of time, the higher the signal quality after the ADC, the higher the reliability of wave recovery during inverse transformation.