Graphic information. Representing an image on a computer What is graphic information

Before looking at any of the basics of digital graphics, it is worth first understanding what graphic information is. Nowadays, this concept is actively used in various fields human activity, but many do not even understand what this term is and what it means.

What it is?

Graphic information Today it is used in most areas of visual communication, ranging from various works of fine art, which should awaken emotions in a person and evoke a feeling of admiration for beauty, and ending with all kinds of symbols intended solely to convey certain information to a person. In particular, such symbols include road signs, which for experienced drivers sometimes do not even reach the area of ​​conscious perception.

Today, graphic information and images represent the basis of the thinking of most specialists, and a special place is given here to people who have a visual-figurative mindset. Possession computer equipment when visualizing any ideas, it is very useful, but it requires thorough preparation, as well as an understanding of specific graphic information from the point of view of translating it into a computer format.

Definition

Graphic information is a complete set of data printed on a wide variety of media, including tracing paper, paper, canvas, glass, walls and much more. To a certain extent, we can say that even you and I, at which the lens of a camera or camera is directed, also represents graphic information.

Widest variety of graphics media available to modern man types of images are, in principle, difficult to take into account, and this happens so far not for the reason that they are presented in an infinite number, but because there are a lot of different intermediate options. After all, we cannot simply add them together and construct a kind of alphabet, and this is what distinguishes such concepts as graphic information and text information. However, there are certain exceptions here too.

Considering what constitutes graphic information and text information, it is worth noting that the set of text characters has long been brought into a certain system called the alphabet. At the same time, in European countries the alphabet is phonetic, while among the Far Eastern peoples the alphabet does not record phonemes or sounds, but represents a whole concept and consists of hieroglyphs, which translates it into the category of not textual, but graphic information.

Useful examples

Not everyone understands that modern European languages ​​also use a unique principle of hieroglyphs, which are represented in our country by numbers. Despite the fact that in different languages numbers can be written exactly the same, in fact they are named and pronounced completely differently in each individual language, which is the typical principle of the hieroglyph.

In this regard, all the elements that are required to implement the coding procedure have been identified a long time ago over a long historical period. Elements that are separate and independent from each other can be represented in the form of a defined list, in which there is a finite and clearly defined number of lines.

The time when a person studies graphic information in the most detail is 9th grade, but many may not even remember this. At the same time, even then we were taught that if we turn to graphic data, including paintings, photographs, drawings or any other visual objects, then in this case it will no longer be possible to find in them such natural and universal elements that could operate in exactly the same way as with letters.

Story

It is worth noting that there have been attempts to form unified system images. In particular, William Hogarth, an English painter and art theorist, tried to do this. In this case, his example is interesting not for the reason that he is a master of the satirical everyday genre, the main goal of which was to expose the vices of the aristocracy, but because it was he who tried to invent a universal graphic alphabet, which he failed. However, the curve, which the artist was able to identify as a reference back in the 18th century, is somewhat reminiscent of the Bezier curve in appearance.

Why can't I create an alphabet?

In fact, it is simply impossible to invent a graphic alphabet, and this is precisely the difference that separates standard writing and modern visual activity. This is also mentioned in the subject that studies graphical information - computer science. These areas are quite close in essence, but the alphabet is universal remedy, which, having a limited number of elements, allows you to create an unlimited number of texts, while in the field of visual activity such a strict list of elements simply cannot exist.

It is for this reason that coding ability is based on a different approach compared to standard elements like numbers and letters, and is primarily learned through how various tasks are performed. Graphic information is a more complex concept than textual information, therefore its development should be approached more thoroughly.

What do you need to understand?

Since in the field of visual activity there cannot be a strict list of elements, compiling a list of them is impossible, and here a serious task arises - to determine how all kinds of digital codes or images can be converted if only computer devices can work with them. In particular, this task is specified by the fact that it is necessary to invent a method that would allow in modern computer technologies operate not only with text.

What are the differences between computer and human perception?

Obviously, there are a lot of differences between how a computer and a person perceive graphics and audio information. For a person, each image, which may be far from a realistic photograph, represents a meaningful structure, because every person can distinguish, for example, a landscape from a portrait.

This becomes possible for the reason that visual perception is not the result of the work of the visual organs alone, but is also the result of a powerful intellect that has amazing recognition abilities. For example, thanks to this, a person can easily recognize another person, even if he has not seen him for several decades, but the latter has already aged a little and his appearance has become different.

Technical systems, in the process of which even the most modern computing power is used, cannot yet implement such tasks.

Test on graphical information in computer science

The final stage by which schools complete the study of what graphic information represents is a test that varies depending on the educational institution and its focus. However, in most cases, all questions are standard and quite simple. Among the most common, it is worth noting the following:

• What happens to the file size as it increases in size
• What are the tools of the Paint graphic editor used for?
• What is the smallest image element on a graphics screen?
• What's happened
• What is it needed for graphics editor?

And many others.

In other words, in the process of compiling this test, the main goal is to determine how much the student has mastered the basic concepts of the graphic information course and how much he has mastered working with traditional graphic editors.

1.1. Types of information. At home, at school, on the street, a person is surrounded by various objects that can be described in words, photographed, drawn. Information about objects and phenomena around us, their properties, and condition is called information.

Information perceived by vision - texts, photographs, drawings, signs - is called visual, i.e. visual; information perceived by hearing - speech, music, various signals- called sound. There are other types of information.

Visual information presented in the form of graphs, drawings, pictures, diagrams, etc. is called graphic.

1. What types of information can you name?
2. What information is called graphical? Give examples.

1.2. Images. Even in ancient times, people learned to depict various animals, household items, labor, and hunting. Images that are many thousands of years old have been found on rocks and in caves. They are made with paints, soot, and charcoal.

Images accompanied man at all stages of his historical development.

Today the world of images is extremely rich. So, in museums and at exhibitions you come across works of painting and graphics. School textbooks, scientific and popular literature are illustrated with a variety of images in the form of drawings, graphs, photographs, diagrams, and drawings. You see the images on television and movie screens.

Any image is a type of visual information.

1. Give examples of using images in practice.
2. Name some types of images that you know.

1.3. Graphic images. From the numerous images that surround us in life, we will choose those that are graphic. Graphic images consist of dots, lines, strokes and are made with pencil, chalk, ink, felt-tip pen on paper, cardboard, fabric, chalkboard.

Some graphic images- drawings, engravings, posters - represent samples artistic graphics, others - drawings, geographical maps, graphs, diagrams, diagrams, developments, sketches, technical drawings - are production or educational.

Road and trade signs, logos are examples of applied (practical) graphics.

Some graphic images are shown in Figure 1.

Rice. 1

1. What images are considered graphic?
2. Give examples of graphic images and describe them.

1.4. Blueprints. In production and in school workshops, images such as drawings are widely used.

Consider Figure 2, which shows a drawing of the part. As you can see, the drawing contains images and various inscriptions. From the images one can judge the geometric shape of a given part and the shape of its individual parts. According to the inscriptions - about the name of the part, the scale in which the images are made, the material from which the part is made, etc. Dimensional numbers make it possible to judge the size of the part as a whole and its individual parts. The drawing contains data on the quality of processing of the part during its manufacture, as well as some other symbols.

Rice. 2

A drawing is a set of graphic and symbolic components that, together with explanatory text, give a variety of characteristics to the objects depicted on it. Through lines, symbols, inscriptions, and symbols, the drawing conveys a variety of information about the subject. The drawing should give a complete picture of the part.

Thus, drawing is a graphic document that defines the design of a particular product and contains information necessary for its development, manufacture, control, installation, operation and repair 1.

1 On training drawings it is allowed not to include all the data that production drawings should contain. In some cases, we will call only the image of a part a drawing.

1. What product data does the drawing contain?
2. Define drawing.
3. Find in the CTS definitions of the following concepts: product, part, part elements.

1.5. The value of drawings in practice. Drawings are one of the main types of graphic information. In modern production, drawings play a special role. In factories and workshops, various products are made: machines, cars, radio devices, household appliances and much more. It is impossible to create all this without drawings. Manufactured according to drawings individual parts machines, assemble complex devices and mechanisms from finished parts, carry out their repair and control.

For the construction of buildings, structures, construction of dams, mines, laying highways and railways use architectural and engineering drawings.

But drawings are needed not only in technology. They are constant companions of many human professions. Furniture is made according to drawings, cities and towns are landscaped. Drawings are needed by a doctor (to study medical technology), a fashion designer (to design clothes and shoes), and many other specialists.

Drawings as a form of graphic information are sent from plant to plant, from country to country. A person of any specialty, if he knows how to read drawings, will understand them and use them to study the structure of the most complex machine. Therefore, to become a technically literate person, you need to have a good knowledge of the basics of graphic information.

A drawing is also a kind of graphic international language. It is understandable to any specialist, regardless of what language he speaks. A drawing is a concise means of expressing technical ideas.

The graphic language originates from primitive drawings - pictograms (from the Latin pictus - drawn). With their help, people conveyed information about ongoing phenomena, events, objects, etc.

Currently, the principle of pictography as a way of depicting objects using conventional signs is widely used in auxiliary means of communication (from the Latin communicatio - message, connection, path). These include logos of enterprises and firms, advertising and other types of applied graphics.

Modern drawing has come a long way in development. Centuries passed before the graphic images took on their real form. We will get acquainted with the history of their development later, after studying the methods of constructing drawings.

1. Why is drawing called graphic language?
2. How are drawings used in human practice?

Under graphic information refers to a drawing, a drawing, a photograph, a picture in a book, an image on a TV screen, etc. we will consider it as example image on the TV screen. This image consists of a number of horizontal lines - rows. And each line, in turn, consists of the smallest elementary image units - points, which are called pixels (picsel–PICture’SElement– picture element). The entire array of elementary image units is called raster (Latin Rastrum – rake). Degree of clarity image depends on the number of lines on the entire screen and the number of dots in the line that represent resolution screen or just permission .

Monochrome image - an image consisting of any two contrasting colors - black and white, green and white, brown and white, etc. each pixel of the image can have either one or the other color. By assigning the binary code “0” to the first color, and the code “1” to the second (or vice versa), you can encode the state of one pixel of a monochrome image in one bit.

However, the resulting image will have too much contrast. A real, for example, black and white image consists of not only white and black colors. It includes many different intermediate shades - gray, light gray, dark gray, etc. If, in addition to white and black, only two additional gradations are used, then in order to encode the color state of one pixel, two bits will be required.

A common practice that produces realistic monochrome images is to encode the state of a single pixel using a single byte, which allows for 256 different shades of gray from completely white to completely black.

Color image can be formed in various ways. One of them - method RGB (from the words Red, Green, Blue - red, green, blue), which relies on the fact that the human eye perceives all colors as the sum of three primary colors - red, green and blue. To obtain a color pixel, not one, but three color rays are sent to the same place on the screen. For simplicity, we will assume that one bit is enough to encode each color. “0” in a bit means that this primary color is absent in the total color, and “1” means that it is present. Therefore, 3 bits are required to encode one color pixel. With this coding scheme, each pixel can have one of 8 possible colors. If each color is encoded using one byte, then it will be possible to transmit 256 shades of each of the primary colors. In total, in this case, the transmission of 256 X 256 X 256 = 16777216 different colors is provided, which is quite close to the real sensitivity of the human eye. This method of presenting color graphics is usually called the mode True Color (truecolor – true color) or full color mode .

There are other full-color color image encoding modes. They require a lot of memory. In order to save memory, various modes and graphic formats are being developed that reproduce color a little worse, but require much less memory. In particular, the mode High Color (highcolor-rich color), in which 16 bits are used to transmit the color of one pixel and, therefore, 65535 color shades can be transmitted.

When recording an image into computer memory, in addition to the color of individual dots, it is necessary to record a lot of additional information - the size of the picture, the brightness of the dots, etc. A specific method of encoding all the information required when recording an image forms a graphic format. Graphic information encoding formats based on the transmission of the color of each individual pixel that makes up the image are classified as raster or BitMap formats (bitmap). The most well-known raster formats are BMP ,GIF And JPEG formats.

Raster graphics have significant disadvantage – an image encoded in one of the raster formats scales very poorly. Therefore, methods have been developed vector graphics . IN vector graphics the base object is line . In this case, the image is formed from individual segments of straight or curved lines, described mathematically, in a vector way, as well as geometric shapes - rectangles, circles, etc., which can be obtained from them.

Vector graphics

Main logical element vector graphics is a geometric object. The objects accepted are simple geometric shapes (so-called primitives - rectangle, circle, ellipse, line), composite shapes or shapes built from primitives, color fills, including gradients.

Rice. 1.

The advantage of vector graphics is that the shape, color and spatial position of its constituent objects can be described using mathematical formulas.

An important object in vector graphics is the spline. A spline is a curve by which one or another geometric figure is described. Modern TryeType and PostScript fonts are built on splines.

Vector graphics have many advantages. It is economical in terms of the disk space required to store images: this is due to the fact that it is not the image itself that is saved, but only some basic data, using which the program recreates the image each time. In addition, describing color characteristics does not increase the file size at all.

Vector graphics objects are easily transformed and modified, which has virtually no effect on image quality. Scaling, rotation, curvature can be reduced to a couple of elementary transformations on vectors.

In those areas of graphics where maintaining clear and precise outlines is important, for example, in font compositions, in creating logos, etc., vector programs are indispensable.

Rice. 2.

Vector graphics can also include fragments raster graphics: the fragment becomes the same object as all the others (albeit with significant limitations in processing).

An important advantage of vector graphics programs is the developed means of integrating images and text and a unified approach to them. Therefore, vector graphics programs are indispensable in the field of design, technical drawing, for drawing, graphic and design work.

However, on the other hand, vector graphics may seem overly rigid, “plywood”. It is really limited in purely pictorial means: it is almost impossible to create photorealistic images in vector graphics programs.

And, in addition, the vector principle of image description does not allow automating the input of graphic information, as a scanner does for bitmap graphics.

Recently, 3D modeling programs, also of a vector nature, have become increasingly widespread.

Featuring sophisticated rendering techniques (ray tracing, emissivity), these programs allow you to create photorealistic raster images with arbitrary resolution from vector objects with moderate effort and time.

In any case, if you work with graphics, you will inevitably deal with both of its forms - vector and raster. Understanding their strengths and weaknesses will allow you to do your job as efficiently as possible.

Vector graphics describe images using straight and curved lines called vectors, as well as parameters describing colors and layout. For example, an image of a tree leaf is described by points through which a line passes, thereby creating the outline of the leaf. The leaf color is determined by the color of the outline and the area within that outline.

When editing vector graphic elements, you change the parameters of straight and curved lines that describe the shape of these elements. You can move elements, change their size, shape and color, but this will not affect the quality of their visual presentation. Vector graphics are independent of resolution, i.e. can be displayed in a variety of output devices with different resolutions without loss of quality.

Vector representation consists of describing image elements with mathematical curves indicating their colors and occupancy (remember, a circle and a circle are different shapes). A red ellipse on a white background will be described by just two mathematical formulas - a rectangle and an ellipse of corresponding colors, sizes and locations. Obviously, such a description will take up much less space than in the first case. Another advantage is high-quality scaling in any direction. Increasing or decreasing objects is done by increasing or decreasing the corresponding coefficients in mathematical formulas. Unfortunately, the vector format becomes disadvantageous when transferring images with a lot of shades or fine details (for example, photographs). After all, every smallest highlight in this case will appear not as a collection of single-color dots, but as a complex mathematical formula or a set of graphic primitives, each of which is a formula. This makes the file heavier. In addition, converting an image from raster to vector format (for example, Adobe program Streme Line or Corel OCR-TRACE) leads to the latter inheriting the inability to correctly scale up. As linear dimensions increase, the number of details or shades per unit area does not increase. This limitation is imposed by the resolution of input devices (scanners, digital cameras, etc.).

Raster graphics

Raster graphics describe images using colored dots, called pixels, arranged on a grid. For example, an image of a tree leaf is described by the specific location and color of each grid point, creating an image much like a mosaic.

When editing raster graphics, you are editing pixels, not lines. Raster graphics are resolution-dependent because information describing the image is attached to a grid of a specific size. When editing raster graphics, the quality of its presentation may change. In particular, resizing raster graphics can cause the edges of the image to become frayed as the pixels are redistributed on the grid. Outputting raster graphics to devices with a lower resolution than the resolution of the image itself will reduce its quality.

The basis of the raster representation of graphics is a pixel (dot) indicating its color. When describing, for example, a red ellipse on a white background, you have to indicate the color of each point, both the ellipse and the background. The image is represented as a large number of dots - the more there are, the visually better the image and the larger the file size. Those. one or even a picture can be presented with better or worse quality in accordance with the number of dots per unit of length - resolution (usually dots per inch - dpi or pixels per inch - ppi).

In addition, quality is also characterized by the number of colors and shades that each point in the image can take on. The more shades an image is characterized by, the more digits are required to describe them. Red can be color number 001, or it can be color number 00000001. Thus, the higher the quality of the image, the larger the file size.

Raster representation is typically used for photographic-type images with a lot of detail or shading. Unfortunately, scaling such images in any direction usually degrades the quality. When the number of dots is reduced, small details are lost and the inscriptions are deformed (although this may not be so noticeable if the visual size of the image itself is reduced - i.e., the resolution is maintained). Adding pixels leads to a deterioration in the sharpness and brightness of the image, because new points have to be given shades that are average between two or more adjacent colors. Common formats are .tif, .gif, .jpg, .png, .bmp, .pcx, etc.

Thus, the choice of raster or vector format depends on the goals and objectives of working with the image. If photographic color accuracy is needed, then a raster is preferable. It is more convenient to present logos, diagrams, and design elements in vector format. It is clear that in both raster and vector representation, graphics (as well as text) are displayed on a monitor screen or printing device in the form of a collection of points. On the Internet, graphics are presented in one of the raster formats that browsers can understand without installation. additional modules- GIF, JPG, PNG.

Without additional plugins (add-ons), the most common browsers only understand raster formats - .gif, .jpg and .png (the latter is not yet widespread). At first glance, the use of vector editors becomes irrelevant. However, most of these editors provide export to .gif or .jpg at the resolution you choose. And it is easier for beginning artists to draw in vector media - if the hand trembles and the line goes in the wrong direction, the resulting element is easily edited. When drawing in raster mode, you risk irreparably damaging the background.

Due to the features of image representation described above, for each type you have to use a separate graphic editor - raster or vector. Of course, they have common features - the ability to open and save files in different formats, use tools with the same names (pencil, pen, etc.) or functions (select, move, zoom, etc.), choose the desired color or shade... However, the principles for implementing the drawing and editing processes are different and are determined by the nature of the corresponding format. So, if in raster editors they talk about selecting an object, they mean a collection of points in the form of an area of ​​complex shape. The extraction process is very often labor-intensive and painstaking work. When you move such a selection, a “hole” appears. In a vector editor, an object represents a set of graphic primitives, and to select it, you just need to select each of them with the mouse. And if these primitives were grouped by the appropriate command, then it is enough to “click” once on any of the points of the grouped object. Moving a selected object exposes underlying elements.

However, there is a trend towards convergence. Most modern vector editors are able to use raster images as backgrounds, or even convert parts of the image into vector format using built-in tools (tracing). Moreover, there are usually tools for editing the loaded background image, at least at the level of various built-in or installed filters. The 8th version of Illustrator is able to load Photoshop .psd files and use each of the resulting layers. In addition, to use the same filters, a direct translation of the generated vector image into a raster format and further use as a non-editable raster element. Moreover, all this is in addition to the usually available converters from vector to raster format with obtaining the corresponding .

Some raster editors are able to load one of the vector formats (usually .wmf) as a background or immediately convert them to a raster with the possibility of direct editing.