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. Both one object and several can receive information.
For better data exchange, information is simultaneously encoded and processed on the transmitter side (data is prepared and converted into a form convenient for broadcasting, processing and storage), forwarding and decoding is carried out on the receiver side (encoded data conversion to its 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 is usually implemented on the basis of computer technology.
Coding information on a computer
There are many ways to process data (texts, numbers, graphics, video, sound) usingcomputer. All information processed by a computer is represented in binary code - using the numbers 1 and 0, called bits. Technically, this method is implemented very simply: 1 - the electrical signal is present, 0 - absent. From a human point of view, such codes are inconvenient for perception - long strings of zeros and ones, which are encoded characters, are very difficult to decipher immediately. But such a recording format immediately clearly shows what information encoding is. For example, the number 8 in binary eight-digit form looks like the following bit sequence: 000001000. But what is difficult for a person is simple for 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, looks it up in the standard ASCII character table (American Code for Information Interchange), “understands” which button is pressed and passes this code for further processing (for example, to display the character on the monitor). To store a character code in binary form, 8 bits 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 pseudographics.
Text encoding
It will be easier to understand what information encoding is with an example. Consider the codes of the English character "C"and the Russian letter "C". Note that the characters are uppercase, and their codes differ from lowercase ones. The English character will look like 01000010, and the Russian one will look like 11010001. What looks the same to a person on a monitor screen, a computer perceives completely differently. It is also necessary to pay attention to the fact that the codes of the first 128 characters remain unchanged, and starting from 129 and further, different letters can correspond to one binary code, depending on the code table used. For example, decimal code 194 can correspond to the letter “b” in KOI8, “B” in CP1251, “T” in ISO, and not a single character corresponds to this code in CP866 and Mac encodings. Therefore, when we see letter-character abracadabra instead of Russian words when opening the text, this means that such encoding of information does not suit us and we need to choose another character converter.
Number encoding
In the binary system, only two variants of the value are taken - 0 and 1. All 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 occupies two bytes (16 bits): 5 - 01010011, 4 - 01000011. In order to use this number in calculations, it is converted by special algorithms into the binary system in the form of an eight-digit binary number: 45 - 00101101.
Coding and processinggraphic information
In the 50s, computers that were most often used for scientific and military purposes were the first to implement 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 made an extraordinary revolution in working with technology. Perhaps the influence of the human psyche had an effect: visually 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 representation of graphics
Graphic information can be of two types: analog (a painting canvas with continuously changing color) and discrete (a picture consisting of many dots of different colors). For the convenience of working with images on a computer, they are processed - spatial sampling, in which each element is assigned a specific color value in the form of an individual code. Encoding and processing of graphic information is similar to working with a mosaic consisting of a large number of small fragments. Moreover, the coding quality depends on the size of the dots (the smaller the size of the element - there will be more dots per unit area - the higher the quality) and the size of the palette of colors used (the more color states each dot can take, respectively, carrying more information, the betterquality).
Creating and storing graphics
There are several basic image formats - vector, fractal and raster. Separately, a combination of raster and vector is considered - a multimedia 3D graphics that is widespread in our time, which is the techniques and methods for constructing three-dimensional objects in virtual space. The encoding and processing of graphics and multimedia information is different for each image format.
Bitmap
The essence of this graphic format is that the picture is divided into small multi-colored dots (pixels). Upper left control point. The coding 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, the higher the image quality. You can use binary code to process raster-type graphic data, since the brightness of each point and the coordinates of its location can be represented as integers.
Vector Image
Coding of graphic and multimedia information of a vector type is reduced to the fact that a graphic object is represented in the form of elementary segments and arcs. propertieslines, which are the basic object, are the shape (straight or curve), color, thickness, style (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 start and end points of the line and the curvature radius of the arc. The amount of graphic information in vector format is much less than raster format, but it requires special programs to view graphics of this type. There are also programs - vectorizers that convert raster images into vector ones.
Fractal graphics
This type of graphics, like vector graphics, is based on mathematical calculations, but its basic component is the formula itself. There is no need to store any images or objects in the computer's memory, the picture itself is drawn only according to the formula. This type of graphics is convenient for visualizing not only simple regular structures, but also complex illustrations that imitate, for example, landscapes in games or emulators.
Sound waves
What is information encoding can also be demonstrated using the example of working with sound. We know that our world is filled with sounds. Since ancient times, people have figured out how sounds are born - waves of compressed and rarefied air that affect the eardrums. A person can perceive waves with a frequency of 16 Hz to 20 kHz (1 Hertz - one oscillation per second). All waves whose oscillation frequencies fall within thisrange are called audio.
Sound Properties
The characteristics of sound are tone, timbre (the color of the sound, depending on the shape of vibrations), pitch (frequency, which is determined by the frequency of vibrations per second) and loudness, depending on the intensity of vibrations. Any real sound consists of a mixture of harmonic vibrations with a fixed set of frequencies. The vibration with the lowest frequency is called the fundamental tone, the rest are overtones. The timbre - a different number of overtones inherent in this particular sound - gives a special color to the sound. It is by timbre that we can recognize the voices of loved ones, distinguish the sound of musical instruments.
Programs for working with sound
Programs can be conditionally divided into several types according to their functionality: 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 converters (DAC).
Audio encoding
Coding of multimedia information consists in converting the analog nature of sound into a discrete one 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 at the output with data on amplitude changes. No physical transformation takes place.
The output signal is discrete, so the more oftenamplitude measurement frequency (sample), the more accurately the output signal corresponds to the input signal, the better is the encoding and processing of multimedia information. A sample is also commonly referred to as an ordered sequence of digital data received through an ADC. The process itself is called sampling, in Russian - discretization.
The reverse conversion occurs with the help of a DAC: based on the digital data entering the input, an electrical signal of the required amplitude is generated at certain points in time.
Sampling parameters
The main sampling parameters 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 value of the signal amplitude is transmitted during digitization in each unit of time, the higher the quality of the signal after the ADC, the higher the reliability of wave recovery during inverse conversion.
