Download the summary of the lesson on coding textual information. Lesson development and presentation on the topic "encoding textual information"

Item: Computer science.

Class: 10

Lesson topic:“Coding of text (character) information”.

Lesson type: Educational.

Lesson Objectives:

• 
  To introduce students to the ways of encoding information in a computer;
• 
  Consider examples of problem solving;
• 
  To promote the development of cognitive interests of students.
• 
  Cultivate endurance and patience in work, a sense of camaraderie and mutual understanding.

• 
  To form students' knowledge on the topic “Coding of text (character) information”;
• 
  To promote the formation of figurative thinking among schoolchildren;
• 
  Develop skills of analysis and introspection;
• 
  Develop the ability to plan your activities.

• 
  workplaces of students (personal computer),
• 
  workplace teachers,
• 
  interactive board,
• 
  workshop on informatics and information technology(authors: N. Ugrinovich, L. Bosova, I. Mikhailova),
• 
  multimedia projector,
• 
  multimedia presentation,
• 
  electronic cards zadachi.htm, kart_1(2,3).exe.

I. Organizational moment.

The first slide on the whiteboard multimedia presentation with the topic of the lesson.

Teacher: Hello guys. Sit down. Duty officer, report the missing. (Report of the attendant). Thank you.

II. Work on the topic of the lesson.

1. Explanation of new material.

The explanation of the new material takes place in the form of a heuristic conversation with the simultaneous display of a multimedia presentation on an interactive whiteboard (Annex 1).

Teacher: What kind of information encoding did we study in previous lessons?

Answer: Encoding of numerical information and representation of numbers in a computer.

Teacher: Let's move on to the study of new material. Write down the topic of the lesson “Coding text information” (slide 1). Issues under consideration ( slide 2):

Historical excursion;

Binary encoding of textual information;

Calculation of the amount of text information.

Historical digression

Mankind has been using text encryption (encoding) since the very moment when the first secret information appeared. Here are several text encoding techniques that were invented at various stages in the development of human thought ( slide 3) :

- cryptography- this is cryptography, a system for changing writing in order to make the text incomprehensible to uninitiated persons;

- morse code or non-uniform telegraphic code, in which each letter or character is represented by its own combination of short elementary parcels electric current(dots) and elementary parcels of triple duration (dashes);

- sign language is a sign language used by people with hearing impairments.

Question: What other examples of encoding textual information can be given?

Students give examples.

Traditionally, 1 byte of information is used to encode one character.

Question: How many different characters can be encoded?

Student response: N = 2 I = 2 8 = 256.

Teacher: Right. Is this enough to represent textual information, including uppercase and lowercase letters of the Russian and Latin alphabets, numbers and other symbols?

Children count the number of different characters:

33 lowercase letters of the Russian alphabet + 33 uppercase letters = 66;

For the English alphabet 26 + 26 = 52;

Numbers from 0 to 9, etc.

Teacher: What is your conclusion?

Withdrawal of students: It turns out that 127 characters are needed. There are still 129 values ​​left that can be used to indicate punctuation marks, arithmetic signs, service operations (line feed, space, etc.). Therefore, one byte is enough to encode the necessary characters for encoding textual information.

Teacher: In a computer, each character is encoded with a unique code.

An international agreement has been adopted to assign each character its own unique code. The ASCII code table (American Standard Code for Information Interchange) has been adopted as an international standard ( slide 7).

This table contains codes from 0 to 127 (letters of the English alphabet, signs of mathematical operations, service symbols, etc.), and codes from 0 to 32 are assigned not to symbols, but to function keys. Write down the name of this code table and the range of characters to be encoded.

Codes 128 to 255 are assigned to the national standards of each country. This is sufficient for most developed countries.

For Russia, several different code table standards have been introduced (codes 128 to 255).

What word did you get?

Answer: bit.

Teacher: Close the file without saving.

Concept of Unicode encoding

СР1251: 208 232 236

COI8-R:242 201 205

Using an engineering calculator, we will translate the sequence of codes from the decimal number system to hexadecimal. We get:

CP1251: D0 E8 EC

KOI8-R: F2 C9 CD

(Switch to presentation view mode).

Work in pairs. (The class is divided into pairs).

Teacher: Let's encode the words offered to you on the cards using the same encoding tables.

Read carefully the task on the slide ( slide 13).

Exercise: All concepts are used in computer science or related to it. Define these concepts and code them using tables KOI8-R or CP1251. Use the engineering calculator to convert the sequence of codes from decimal to hexadecimal. Enter the received hexadecimal code without spaces in the corresponding Input field. Click the Check button and verify that the solution is correct. Concepts should be written in capital letters, except for geographical names.

(When preparing electronic cards, the level of difficulty for different groups of students should be taken into account).

Teacher: Name the conceived terms or concepts. Who got the correct code? Who didn't succeed? What is your mistake, what do you think?

students answer questions in the form of a discussion.

(Switching to the interactive mode of the board).

Teacher: Now let's move on to solving problems on the amount of textual information and quantities related to determining the amount of textual information.

Write down the condition of problem number 1. (On the interactive whiteboard - the condition of problem number 1.) Assuming that each character is encoded by one byte, estimate the information volume of the following sentence:

“My uncle of the most honest rules, When he fell seriously ill, He forced himself to respect And could not invent better.

Solution: There are 108 characters in this phrase, including punctuation marks, quotation marks and spaces. We multiply this number by 8 bits. We get 108*8=864 bits. Are there any issues to resolve?

Students ask questions if they come up.

The teacher answers questions or one student answers another question.

Teacher: Consider problem number 2. (The condition is displayed on the interactive whiteboard). Write down the condition: Laser printer Canon LBP prints at an average speed of 6.3 Kbps. How long will it take to print an 8-page document if it is known that there are an average of 45 lines on one page, 70 characters per line (1 character - 1 byte) (see Fig. 2).

Solution:

1) Find the amount of information contained on 1 page:

45 * 70 * 8 bits = 25200 bits

2) Find the amount of information on 8 pages:

25200 * 8 = 201600 bits

3) We bring to uniform units of measurement. To do this, we translate Mbits into bits:

6.3*1024=6451.2 bps

4) Find the print time: 201600: 6451.2? 31 seconds.

Your questions.

students ask questions if they arise.

The teacher answers questions or one student answers another question.

Teacher: Now let's solve problems on electronic cards. Open the zadachi.htm file. (Annex 5)(The teacher calls the number of the card, for each student. One student solves problems at the blackboard). Solve the problems and write down the answer in the corresponding input field.

During the task, the teacher checks the answers of the students.

III. Generalization

1. What is the principle of encoding textual information used in a computer?

2. What is the name of the international character encoding table?

3. List the names of encoding tables for Russian characters.

4. In what number system are the codes in the encoding tables you listed?

IV. Homework

(Slide 15) According to Ugrinovich's textbook § 2.10, workshop on computer science and information technology § 2.7, tasks for independent completion 2.58-2.63 (for students with weak motivation to learn) (2.58-2.66 for other students).

The teacher sums up the lesson and gives grades.

Goodbye, thanks for the lesson.

Lesson topic: "Coding of textual information".

Item: Informatics and ICT.

Class: 8

Teacher: Strokach Natalya Petrovna

Lesson outline

Equipment : computer, multimedia projector, whiteboard, student workstations (personal computers), textbook “Informatics and ICT. Grade 9 "N.D. Ugrinovich.

Lesson type : combined.

Forms of work : frontal, collective, individual.

Material for the lesson: presentation, code tables (ASCII, 5 code tables of the Russian language:Windows, ISO, Mac, MS- DOS, KOI-8), worksheets practical work.

Lesson Objectives:

Tutorials:

Introduce the concepts of textual information;

to form students' idea of ​​how text information is encoded in computer memory;

Learn to determine the character code and the character by code using code tables and a text editor. Learn to encode and recode textual information.

Developing:

Development of logical thinking, attention, memory;

Development of sustainable cognitive interest among students;

Educational:

Formation of interest in the subject, the formation of a worldview;

Cultivating a culture of behavior in the classroom, listening skills.

Requirements for knowledge and skills:

Students should know:

The principle of encoding textual information;

The structure of the ASCII encoding table.

Students should be able to:

Encode and decode characters using a code table;

Lesson plan:

Organizing time (3 min)

Knowledge update

Learning new material - read the presentation (15 min)

Fixing the material. Completing tasks (17 min)

Checking, grading, homework (5 min)

During the classes:

Organizing time.

Setting a cognitive task

Question:

What kinds of information can a computer process? (numeric, graphic, text, audio, video)

Question:

How is information stored in computer memory? (in binary)

Question:

How is the conversion of graphic information from analog to discrete? (by spatial sampling, the image is divided into pixels)

Question:

How is audio converted to digital form? (using time sampling)

Question:

What information do you think a person most often processes using a computer?

At present, most personal computers in the world (both in quantity and in time) is occupied by the processing of textual information.(slide 1,2)

3. Reporting the topic, conveying the goals of the lesson

Today the topic of our lesson: "Coding text information"(slide 3,4).

The purpose of the lesson (slide 5)

To get acquainted with the concepts of encoding textual information, code table.

Learn to determine the character code and character by code using text editors.

4. Introduction of new knowledge.

Question:

How many characters are needed to encode textual information?

Let's use the method of "estimation". To do this, we need to remember what symbols we use in writing.

33*2(uppercase and lowercase) + 10(numbers) + 10(punctuation marks) = 86 characters.

Question:

Are all texts in Russian? What characters should be added to the keyboard?

For the English alphabet 26 + 26 = 52;

It turns out that 127 characters are needed. There are still 129 values ​​that can be used to indicate punctuation marks, arithmetic signs, service operations (line feed, space, etc.).

The set of all characters with which the text is written is called the alphabet. (Slide 6)

The number of characters in an alphabet is called its cardinality. (slide 7)

So, there are 256 characters on the keyboard. The computer must be able to recognize and translate all of these characters into binary code.(slide 8)

Question:

How does a computer recognize characters?

The computer distinguishes characters by a combination of electrical impulses - the binary code of the character

How many bits of information can encode 1 character if there are 256 such characters?

Let's remember the formulaN=2 i . (slide 9)

256=2 8 , therefore, 1 character is encoded by 8 bits or 1 byte.(slides 10,11,12).

The binary code of each character can be written as a decimal number.

)Question:

Can you tell which words are encoded by the numbers on the board?(slide 13)

65; 112; 112; 108; 101

200; 216; 228; 224

Question: What is needed to be able to decode these words? (Tables for translation)

Take a table from the edge of the table and name the first word you got (Apple)

What is the second word? There was a problematic situation - tables with codes greater than 127, five. And according to different code tables, different words are obtained. (Code - according to the ISO table)

code table - a table that establishes a correspondence between numerical codes and symbols. (Slide number 14)

There is an internationally accepted code table called ASCII (American Standard Code for Information Interchange) - American Standard Code for Information Interchange. (Slide number 15)

Parts of the ASCII code table:

0-32 are commands and function keys;

33-127 - international part (Latin);

128-255 - the national part.

Historically, the national part of the code tables appeared inconsistently in different countries and in different operating systems Oh. Code tables ISO and KOI-8 appeared in the USSR. The MS-DOS code table was developed for the operating Microsoft systems DOS, Windows code table - for the Microsoft Windows operating system. The Mac code table is used in operating Mac systems OS.

Currently, there are 5 code tables for Russian letters (Windows, MS-DOS, KOI-8, Mac, ISO), so texts created in one encoding will not display correctly in another.

Russian encodings (Cyrillic): (Slide No. 16)

windows,

MS- DOS,

KOI-8,

Mac,

ISO.

Question: Why do you think the last character in the code table has the number 255, and earlier it was said that the codes are 256. (Because the numbering starts from 0.)

Sometimes it becomes necessary to use more than two languages ​​in one text document. For example, when printing text on geometry, you may need Russian characters, Latin letters, Greek letters. How to be in such a situation?

There are approximately 6800 different languages ​​in the world. If you read a text printed in Japan on a computer in Russia or the United States, you will not be able to understand it. To make the letters of any country readable on any computer,1991 was proposed new standard codes, where 2 bytes of memory were allocated for each character.

The code table was called Unicode (Slide No. 17)

There are 65536 characters in the Unicode code table (Slide #18)

Unicode includes almost all modern scripts, including: Arabic, Armenian, Bengali, Burmese, Greek, Georgian, Devanagari, Hebrew, Cyrillic, Coptic, Khmer, Latin, Tamil, Hangul, Han (China, Japan, Korea), Cherokee, Ethiopian, Japanese (katakana, hiragana, kanji) and others.

For academic purposes, many historical scripts have been added, including: ancient Greek, Egyptian hieroglyphs, cuneiform, Mayan script, Etruscan alphabet.

Unicode provides a wide range of mathematical and musical symbols, as well as pictograms.

Notebook entry: (Slide number 19)

Code tables:

ASCII

Unicode

Number of bytes per 1 character

1 byte

2 bytes

Characters

256

65536

So, let's conclude: the same code in different code tables gives different characters.

5. Practical work

Remember the objectives of the lesson.

The first goal is to get acquainted with the concept of encoding textual information, a code table. Tell me, have we achieved this goal? (Yes )

Even before ourselves, we set goals, to achieve which the practical work "Coding of textual information" will help us. (Slide #21)

What goals will we set for ourselves in practical work? (Learn to encode textual information, learn to determine the character code and character by code using code tables and a text editor )

The practical work consists of two parts:

The first part consists of three tasks and is performed on a computer:

Read the tasks to be completed on the computer. What program will we use to complete these tasks? (Text editors MS Word and Notepad).

Now you have a text editor window on your screen. (Slide number 22)

We will determine the character code and find the character by code using insert special characters(Insert → Symbols).

Choosing the required symbol, we see its numerical code in the lower right corner of the window. All characters in the table are sorted in ascending order of numeric codes, so you can find a character with a given numeric code.

You need to write down all the results in a notebook.

Do you have questions about practical work? (No).

You can start doing tasks on computers. Take notebooks and pens. Do not forget about the safety rules, maintaining health when working at a computer.

Students perform work on computers, the teacher observes, helps, corrects work, monitors the correct fit at the computer.

Students who have completed the first part turn off the computers, return to their desks and do the second part of the practical work.

The teacher supervises the work and helps in case of difficulties.

Result:

« WORD»

200 205 212 206 208 204 192 210 200 202 192- "INFORMATICS" in "Windows»

STUDENT

"Notepad": abvgdezhy rstufhtschshsh I want to study

The second part consists of two tasks and is performed in notebooks according to code tables: (slide 23)

204 224 242 229 236 224 242 232 247 229 241 234 232 233 32 235 232 246 229 233

Masha sent her friend Olya a letter written in Windows encoding, and Olya read it in ISO encoding. The result was a meaningless phrase "Yauchf#rtyџў!". Help Olya read the letter.

For those who can complete the tasks faster, an additional task is proposed in the work: Encode the phrase “I came, I saw, I conquered” in ISO encoding.

3. Additional task

Using the Windows code table, decode the phrase:

205 229 32 246 226 229 242 251 130 224 32 226 255 237 243 242

205 229 32 235 224 228 238 248 232 130 32 224 32 232 236 232 245 235 238 239 224 254 242

205 229 32 225 229 235 252 184 130 32 224 32 232 245 32 240 224 231 226 229 248 232 226 224 254 242

205 224 32 237 232 245 32 236 238 230 237 238 32 226 229 248 224 242 252 32 235 224 239 248 243

Divide the children into 4 groups of 3 people. Give each group 1 line. When all the students complete the task, it is checked for completion. Each of the four options has encoded lines from the riddle.

Not flowers, but wither,
Not hands, but they clap,
Not underwear, but they are hung
You can hang noodles on them.

Students take turns reading their text. Let's guess together!

6. Lesson summary

Let's sum up the lesson.

Answer the following questions on the lesson material: (Slide No. 25)

What is needed to encode textual information on a computer? (Code table)

What is the name of the international code table? (ASC II)

How many Russian language encodings are there? (Five)

What was the purpose of introducing the Unicode encoding, which allows you to encode 65,536 different characters?(to encode not only Russian and Latin alphabets, numbers, signs and mathematical symbols, but also Greek, Arabic, Hebrew and other alphabets).

Let's remember the objectives of the lesson: (Slide number 26)

To get acquainted with the concept of encoding textual information, code table.

Learn to encode and recode textual information using code tables.

Learn to determine the character code and character by code using a text editor.

Question: Have we achieved these goals? (Yes, we have reached)

Grading a lesson.

7. Homework

Recording homework in diaries or notebooks: (Slide No. 27)

Textbook, pp. 49 - 52, p. 2.1.

Security questions on page 52

Tasks for self-fulfillment No. 2.1., 2.2.

8. Reflection

Students are given an individual card in which they need to underline the phrases that characterize the student's work in the lesson in three areas.

I am in class

Outcome

1. interesting

1. worked

1. understood the material

2. boring

2. rested

2. learned more than I knew

3.don't care

3.helped others

3.didn't understand

Encoding of text information

Goal of the work: learn to identify numeric character codes, enter characters using numeric codes using encodingWindows, Unicode(Unicode).

Work order:

Exercise 1.

Determining the numeric character code using a text editor Word .

Launch text editorWordcommand [Programs/MicrosoftWord]

Enter command [insert/character]. A dialog box will appear on the screen.Symbol . To determine the numeric code of a character in an encodingWindows from: select encoding typeCyrillic (dec.).

Sign code: the decimal numeric character code will appear (in this case 192).

To determine the hexadecimal numeric character code in the encodingUnicodeusing the drop down listfrom: select encoding type Unicode(hex)

In the symbol table, select a symbol (for example, an uppercase letter "A"). In a text fieldSign code: the hexadecimal numeric character code will appear (in this case 0410).

Task2.

Entering a character using numeric codes in text editor Notebook

Run standard application Notepad command [Programs / Accessories / Notepad]

alt) enter the number 0224, release the key (alt), the symbol "a" will appear in the document. Repeat the procedure for numeric codes from 0225 to 0233, a sequence of 12 characters "abvgdezhy" will appear in the documentencoded Windows .

With the help of additional numeric keypad while pressing the key (alt) enter the number 224, the symbol "p" will appear in the document. Repeat the procedure for numeric codes from 225 to 233, a sequence of 12 characters “rstufhtschshsch” will appear in the documentencoded MS - DOS

Task 3:

Using encodingWindowsMicrosoftWordencode a wordCOMPUTER SCIENCE

Using encodingUnicodelocated in the text editorMicrosoftWorddecode word0423 0427 0415 041 D 0418 041A

Using encodingWindowslocated in the Notepad app, decode the sentence:

0255 0032 0245 0238 0247 0243 0032 0243 0247 0232 0242 0252 0241 0255

Textual information is encoded in binary code through the designation of each character of the alphabet by a certain integer. Using eight binary digits, it is possible to encode 256 different characters. This number of characters is enough to express all characters of the English and Russian alphabets.

In the early years of the development of computer technology, the difficulties of coding textual information were caused by the lack of the necessary coding standards. At present, on the contrary, the existing difficulties are associated with a multitude of simultaneously operating and often conflicting standards.

For in English, which is an unofficial international means of communication, these difficulties have been resolved. The United States Standards Institute has developed and put into circulation ASCII coding system (American Standard Code for Information Interchange - US Standard Code for Information Interchange).

To encode the Russian alphabet, several encoding options have been developed:

1) Windows-1251 - introduced by the company Microsoft; given the widespread use of operating systems (OS) and other software products this company in Russian Federation it has found wide circulation;

2) KOI-8 (Information Exchange Code, eight digits) is another popular encoding of the Russian alphabet, common in computer networks on the territory of the Russian Federation and in the Russian sector of the Internet;

3) ISO (International Standard Organization - International Institute for Standardization) - an international standard for encoding characters of the Russian language. In practice, this encoding is rarely used.

Limited set of codes (256) creates difficulties for developers unified system text encoding. As a result, it was proposed to encode characters not 8-bit binary numbers, but by numbers with a large digit, which caused an expansion of the range of possible code values. The 16-bit character encoding system is called universal - UNICODE. Sixteen bits allows for unique codes for 65,536 characters, which is enough to fit most languages ​​in one character table.

Despite the simplicity of the proposed approach, the practical transition to this system encoding for a very long time could not be realized due to the lack of resources of computer technology, since in the UNICODE coding system everything text documents become automatically doubled. In the late 1990s technical means reached the required level, the gradual translation of documents began and software tools to the UNICODE coding system.

Encoding textual information in a computer is sometimes an essential condition for the correct operation of the device or the display of a particular fragment. How this process occurs during the work of a computer with text and visual information, sound - we will analyze all this in this article.

Introduction

An electronic computer (which we call a computer in everyday life) perceives the text in a very specific way. For her, the encoding of textual information is very important, since she perceives each text fragment as a group of characters isolated from each other.

What are the symbols?

The role of symbols for the computer is not only Russian, English and other letters, but also punctuation marks, as well as other signs. Even the space with which we separate words when typing on a computer is perceived by the device as a symbol. Something very reminiscent of higher mathematics, because there, according to many professors, zero has a double meaning: it is a number, and at the same time does not mean anything. Even for philosophers, the question of a space in the text can become an actual problem. A joke, of course, but, as they say, in every joke there is some truth.

What is the information?

So, in order to perceive information, a computer needs to start processing processes. And what kind of information is there? The topic of this article is the encoding of textual information. We will pay special attention to this task, but we will also deal with other micro-topics.

Information can be textual, numerical, sound, graphic. The computer must start processes that provide encoding of textual information in order to display what we type on the keyboard, for example. We will see symbols and letters, this is understandable. But what does the car see? She perceives absolutely all information - and now we are talking not only about text - as certain sequence zeros and ones. They form the basis of the so-called binary code. Accordingly, the process that converts the information received by the device into an understandable one is called “ binary encoding text information.

Brief principle of the binary code

Why is the coding of information in binary code the most widespread in electronic machines? The text base, which is encoded using zeros and ones, can be absolutely any sequence of characters and characters. However, this is not the only advantage that binary text encoding of information has. The thing is that the principle on which this coding method is arranged is very simple, but at the same time quite functional. When there is an electrical impulse, it is labeled (conditionally, of course) by a unit. No impulse - mark zero. That is, text encoding of information is based on the principle of constructing a sequence of electrical impulses. A logical sequence composed of binary characters is called machine language. At the same time, coding and processing of textual information using a binary code makes it possible to carry out operations in a fairly short period of time.

Bits and bytes

The figure perceived by the machine contains a certain amount of information. It is equal to one bit. This applies to every one and every zero, which make up one or another sequence of encrypted information.

Accordingly, the amount of information in any case can be determined simply by knowing the number of characters in the binary code sequence. They will be numerically equal to each other. 2 digits in the code carry information of 2 bits, 10 digits - 10 bits, and so on. The principle of determining the information volume, which lies in a particular fragment of binary code, is quite simple, as you can see.

Encoding text information in a computer

Right now you are reading an article that consists of a sequence, as we believe, of the letters of the Russian alphabet. And the computer, as mentioned earlier, perceives all information (and in this case too) as a sequence not of letters, but of zeros and ones, denoting the absence and presence of an electrical impulse.

The thing is that one character that we see on the screen can be encoded using a conventional unit of measure called a byte. As written above, the binary code has a so-called information load. Recall that numerically it is equal to the total number of zeros and ones in the selected code fragment. So, 8 bits make 1 byte. In this case, the combinations of signals can be very different, as you can easily see by drawing a rectangle on paper, consisting of 8 cells of equal size.

It turns out that it is possible to encode textual information using an alphabet that has a capacity of 256 characters. What is the point? The meaning lies in the fact that each character will have its own binary code. Combinations “attached” to certain characters start from 00000000 and end with 11111111. If you switch from binary to decimal number system, then you can encode information in such a system from 0 to 255.

Do not forget that now there are various tables that use the encoding of the letters of the Russian alphabet. These are, for example, ISO and KOI-8, Mac and CP in two variations: 1251 and 866. It is easy to make sure that the text encoded in one of these tables will not be displayed correctly in a different encoding. This is due to the fact that in different tables different characters correspond to the same binary code.

This was a problem at first. However, at present, special algorithms are already built into the programs that convert the text, bringing it to the correct form. 1997 was marked by the creation of an encoding called Unicode. In it, each character has at its disposal 2 bytes at once. This allows you to encode text that has much large quantity characters. 256 and 65536: is there a difference?

Graphics encoding

Encoding textual and graphical information has some similarities. As you know, to display graphic information is used peripheral device computer called monitor. Graphics now ( we are talking now about computer graphics) is widely used in various fields. Fortunately, the hardware capabilities of personal computers make it possible to solve rather complex graphic tasks.

Processing video information has become possible in recent years. But the text at the same time is much “lighter” than graphics, which, in principle, is understandable. Because of this, the final size of graphics files must be increased. It is possible to overcome such problems, knowing the essence in which graphic information is presented.

Let's first understand what groups this type of information is divided into. First, it's raster. Secondly, vector.

Raster images are quite similar to checkered paper. Each cell on such paper is painted over in one color or another. This principle is somewhat reminiscent of a mosaic. That is, it turns out that in raster graphics the image is divided into separate elementary parts. They are called pixels. Translated into Russian, pixels mean “dots”. Logically, the pixels are ordered relative to the rows. The graphics grid consists of a certain amount pixels. It is also called a raster. With these two definitions in mind, we can say that bitmap is nothing more than a set of pixels that are displayed on a rectangular grid.

Monitor raster and pixel size affect image quality. It will be the higher, the larger the raster of the monitor. Raster sizes are the screen resolution that every user has probably heard of. One of the most important features that computer screens have is resolution, not just resolution. It shows how many pixels are in one or another unit of length. The resolution of a monitor is usually measured in pixels per inch. The more pixels per unit length, the higher the quality will be, since the “graininess” is reduced.

Audio stream processing

Text encoding and sound information, like other types of encoding, has some features. We will now focus on the last process: encoding audio information.

The presentation of an audio stream (as well as a single sound) can be done in two ways.

Analogue form of sound information presentation

In this case, the value can take on a really huge number different meanings. Moreover, these same values ​​do not remain constant: they change very quickly, and this process is continuous.

Discrete Form of Sound Information Representation

If we talk about the discrete method, then in this case the value can take only a limited number of values. In this case, the change occurs in leaps and bounds. It is possible to encode discretely not only sound, but also graphic information. As for the analog form, by the way.

Analog audio information is stored on vinyl records, for example. But the CD is already a discrete way of presenting information of a sound nature.

At the very beginning, we talked about the fact that a computer perceives all information in machine language. To do this, information is encoded in the form of a sequence of electrical impulses - zeros and ones. Audio encoding is no exception to this rule. To process sound on a computer, you first need to turn it into that same sequence. Only after that, operations can be performed on a stream or a single sound.

When the encoding process occurs, the stream is subjected to temporal sampling. The sound wave is continuous, it develops over small sections of time. In this case, the amplitude value is set for each specific interval separately.

Conclusion

So, what did we find out in the course of this article? Firstly, absolutely all information that is displayed on a computer monitor, before appearing there, is encoded. Secondly, this coding consists in translating information into machine language. Thirdly, machine language is nothing more than a sequence of electrical impulses - zeros and ones. Fourth, for encoding various characters, there are separate tables. And, fifthly, it is possible to present graphic and sound information in analog and discrete form. Here, perhaps, are the main points that we have analyzed. One of the disciplines studying this area is computer science. Encoding of textual information and its basics are explained at school, since there is nothing complicated about it.

Text information consists of characters: letters, numbers, punctuation marks, etc. One byte is enough to store 256 different values, which allows you to place any of the alphanumeric characters in it. The first 128 characters (occupying the seven least significant bits) are standardized using ASCII (American Standard Code for Information Interchange). The essence of encoding is that each character is assigned a binary code from 00000000 to 11111111 or the corresponding decimal code from 0 to 255. Various code tables are used to encode Russian letters (KOI-8R, СР1251, CP10007, ISO-8859-5 ):

KOI8R- eight-bit standard for encoding letters of Cyrillic alphabets (for the UNIX operating system). Developers KOI8R placed the characters of the Russian alphabet at the top of the extended ASCII table in such a way that the positions of the Cyrillic characters correspond to their phonetic counterparts in the English alphabet at the bottom of the table. This means that from the text written in KOI8R, it turns out the text written in Latin characters. For example, the words "high house" take on the form "dom vysokiy";

СР1251– eight-bit coding standard used in OS Windows;

CP10007- eight-bit coding standard used in the Cyrillic alphabet of the Macintosh operating system (Apple computers);

ISO-8859-5 - an eight-bit code approved as a standard for encoding the Russian language.

Graphic information encoding

Graphical information can be presented in two forms: analog And discrete. Painting canvas created by the artist is analog representation example, and the image printed with a printer, consisting of individual (elements) dots of different colors, is discrete representation.

By splitting the graphic image (sampling), the graphic information is converted from analog to discrete form. In this case, coding is performed - assigning a specific value to each element of the graphic image in the form of a code. Creation and storage of graphic objects is possible in several forms - in the form vector, fractal or raster Images. separate subject considered 3D (three-dimensional) graphics, which combines vector and raster imaging methods.

Vector graphics used to represent such graphic images as pictures, drawings, diagrams.

They are formed from objects - a set of geometric primitives (points, lines, circles, rectangles), which are assigned some characteristics, for example, line thickness, fill color.

An image in vector format simplifies the editing process, since the image can be scaled, rotated, and deformed without loss. In this case, each transformation destroys the old image (or fragment), and a new one is built instead. This way of presentation is good for diagrams and business graphics. When encoding a vector image, it is not the image of the object that is stored, but the coordinates of the points, using which the program recreates the image each time.

Main disadvantage vector graphics is the impossibility of photographic quality images. In vector format, the image will always look like a drawing.

Raster graphics. Any picture can be divided into squares, thus obtaining raster - two-dimensional array squares. The squares themselves raster elements or pixels(picture "s element) - elements of the picture. The color of each pixel is encoded by a number, which allows you to specify the order of color numbers for describing the picture (from left to right or top to bottom). The number of each cell in which the pixel is stored is stored in memory.

Drawing in bitmap format

Each pixel is assigned values ​​for brightness, color, and transparency, or a combination of these values. A bitmap image has a number of rows and columns. This storage method has its drawbacks: the larger amount of memory required to work with images.

The volume of a raster image is determined by multiplying the number of pixels by the information volume of one point, which depends on the number of possible colors. In modern computers, the following screen resolutions are mainly used: 640 by 480, 800 by 600, 1024 by 768 and 1280 by 1024 pixels. The brightness of each point and its coordinates can be expressed using integers, which allows the use of binary code in order to process graphic data.

In the simplest case (black and white image without gradation gray color) each point of the screen can have one of two states - “black” or “white”, that is, 1 bit is needed to store its state. Color images are formed in accordance with the binary color code of each point, stored in the video memory. Color images can have different color depths, which are given by the number of bits used to encode the color of a point. The most common color depths are 8, 16, 24, 32, 64 bits.

To encode color graphic images, an arbitrary color is divided into its components. The following coding systems are used:

HSB (H - hue, S - saturation, B - brightness),

RGB (Red- red, Green - green, blue- blue) And

CMYK ( C yan - cyan, Magenta - magenta, Yellow - yellow and Black - black).

The first system is suitable for human, the second - for computer processing, and the last one for printing houses. The use of these color systems is due to the fact that the luminous flux can be formed by radiations that are a combination of "pure" spectral colors: red, green, blue, or their derivatives.

fractal is an object whose individual elements inherit the properties of parent structures. Since a more detailed description of elements of a smaller scale occurs according to a simple algorithm, such an object can be described with just a few mathematical equations. Fractals allow you to describe images that require relatively little memory to represent in detail.

Drawing in fractal format

3D graphics (3D) operates with objects in three-dimensional space. Three-dimensional computer graphics is widely used in cinema, computer games, where all objects are represented as a set of surfaces or particles. All visual transformations in 3D graphics are controlled by operators having a matrix representation.

Audio encoding

Music, like any sound, is nothing more than sound vibrations, by registering which, it can be accurately reproduced. To represent the sound signal in the computer memory, it is necessary to represent the received acoustic vibrations in digital form, that is, to convert them into a sequence of zeros and ones. With the help of a microphone, the sound is converted into electrical vibrations, after which it is possible to measure the amplitude of the vibrations at regular intervals (several tens of thousands of times per second), using a special device - analog to digital converter (ADC). To reproduce sound, a digital signal must be converted to analog using digital-to-analogue converter (DAC). Both of these devices are built into sound card computer. The indicated sequence of transformations is shown in fig. 2.6..

Transformation of an analog signal into a digital one and vice versa

Each measurement of sound is recorded in binary. This process is called sampling (sampling), performed by the ADC.

sample (sample English sample) is the time interval between two measurements of the amplitude of an analog signal. In addition to a period of time, a sample is also called any sequence of digital data that is obtained by analog-to-digital conversion. An important parameter sampling is the frequency - the number of measurements of the amplitude of the analog signal per second. Audio sampling rate range from 8000 to 48000 measurements per second.

Graphical representation of the discretization process

Playback quality is affected sample rate and resolution(the size of the cell reserved for recording the amplitude value). For example, when writing music to CDs, 16-bit values ​​and a sampling rate of 44032 Hz are used.

By ear, a person perceives sound waves having a frequency ranging from 16 Hz to 20 kHz (1 Hz - 1 oscillation per second).

In CD format Audio DVD in one second, the signal is measured 96,000 times, i.e. a sampling frequency of 96 kHz is used. To save hard disk space in multimedia applications, lower frequencies are often used: 11, 22, 32 kHz. This leads to a decrease in the audible frequency range, which means that what is heard is distorted.