Vector formats. The difference between vector graphics and raster graphics

Vector formatsVector format files are especially useful for storing linear elements (lines and polygons), as well as elements that can be decomposed into simple geometric objects (such as text). Vector files do not contain pixel values, but mathematical descriptions of image elements. Based on mathematical descriptions of graphic forms (lines, curves, splines), the visualization program constructs an image.

Vector files are structurally simpler than most raster files and are usually organized as data streams.

Examples of the most common vector formats are AutoCAD DXF and Microsoft SYLK.

WMF. This is a vector format that is used graphic programs Windows OS. This format is used to transmit vector images via clipboard in Windows environment. This format is accepted by almost all programs that work with vector graphics. This format cannot be used for raster images. Disadvantages: color distortion and failure to save a number of parameters that are set for images in graphics programs.

AI. Illustrator internal format. It can be opened by Photoshop and, in addition, this format is supported by all programs related to vector graphics. This format is the best way to transfer vector images from one program to another. Raster graphic elements when transmitted via AI format, in most cases they are lost.

CDR. This is the internal format of the program Corel Draw. This format is very popular, as is the software package itself. Many programs can import vector files V Corel formats Draw. IN CDR format also contains raster graphic objects. This format uses compression, and different compression is applied to vector and raster files.

Metafile formats

The most common metafile formats are WPG, Macintosh PICT and CGM.

Project name

Group Research Topic

Raster graphics, its advantages and disadvantages, scope

Problematic question (research question)

What are the advantages and disadvantages of raster graphics?

Research hypothesis

Raster graphics editors are the best way solving problems of processing graphic images, human artistic creativity.

Objectives of the study

1. Exploring the concept of a bitmap
2. Study of the main characteristics of a raster image
3. Identifying the capabilities of raster editors, analyzing the advantages and disadvantages
4. Practicing techniques for working with raster images

Progress of the study

• What is a raster image?
• What are the sizes of raster image files (large, small)?
• How does the quality of a raster image change when it is converted (resized)?
• How is raster graphics information represented in computer memory?
• What are the main differences between raster graphics file formats?
• What basic operations can be performed with a graphic image?
• What are the advantages of raster images?
• What are the disadvantages of raster images?
• Which graphic editors allow you to create raster images?
• In what areas is it more convenient to use raster graphics editors?
• What can you use raster graphics editors for?

Research results

The concept of a raster image

A raster image is an image that is based on a table. Table cells are pixels. A pixel is a unit of measurement for the size of a raster image. One pixel is one cell in a raster image. Accordingly, raster images consist of pixels, but they are so small that in normal form they are difficult to separate. Each pixel of a raster image has the following properties: color and pixel location coordinates.

Characteristics of raster images

Important image characteristics are:

• number of pixels - number of colors. The number of pixels in width and height can be indicated separately (1024x768, 640x480, ...) or, rarely, the total number of pixels (often measured in megapixels);
• the number of colors used or color depth (these characteristics have the following relationship: , where is the number of colors, and is the color depth);
• color space (color model) RGB, CMYK, XYZ, YCbCr, etc.
• resolution is a reference value indicating the recommended pixel size of the image.

For raster images consisting of dots, the concept of resolution, which expresses the number of dots per unit length, is of particular importance. It is necessary to distinguish between:

• original resolution;
• screen image resolution;
• resolution of the printed image.

Original resolution Original resolution is measured in dots per inch (dpi) and depends on the requirements for image quality and file size, the method of digitizing and creating the original illustration, the selected file format and other parameters. In general, the rule applies: the higher the quality requirement, the higher the resolution of the original should be.

Screen resolution For screen copies of an image, an elementary raster point is usually called a pixel. Pixel size varies depending on the selected screen resolution (from a range of standard values), the resolution of the original, and the display scale. 20-21" Imaging Monitors ( professional class), as a rule, provide standard screen resolutions 640x480, 800x600, 1024x768, 1280x1024, 1600x1200, 1600x1280, 1920x1200, 1920x1600 pixels. The distance between adjacent phosphor points is quality monitor is 0.22–0.25 mm. A resolution of 72 dpi is sufficient for a screen copy, 150–200 dpi for printing on a color or laser printer, and 200–300 dpi for output on a photo exposure device. Installed rule of thumb that when printing, the resolution of the original must be 1.5 times greater than the raster lineage of the output device. If the hard copy is to be enlarged compared to the original, these values ​​should be multiplied by the scaling factor.

Printed image resolution and the concept of lineature The size of a raster image dot both on a hard copy (paper, film, etc.) and on the screen depends on the method used and the rasterization parameters of the original. When rasterizing, a grid of lines is superimposed on the original, the cells of which form a raster element. The frequency of the raster grid is measured by the number of lines per inch (lines per inch – Ipi) and is called lineature. The raster dot size is calculated for each element and depends on the tone intensity in a given cell. The higher the intensity, the denser the raster element is filled. That is, if the cell contains absolutely black color, the size of the raster point will coincide with the size of the raster element. In this case, they talk about 100% occupancy. For absolutely white the occupancy value will be 0%. In practice, element occupancy on a print usually ranges from 3 to 98%. In this case, all raster points have the same optical density, ideally approaching absolute black. The illusion of a darker tone is created by increasing the size of the dots and, as a result, reducing the white space between them with the same distance between the centers of the raster elements. This method is called rasterization amplitude modulation(AM).

Tone intensity (the so-called lightness) is usually divided into 256 levels. A larger number of gradations is not perceived by human vision and is redundant. A smaller number worsens the perception of the image (the minimum acceptable value for a high-quality halftone illustration is 150 levels). It is easy to calculate that to reproduce 256 tone levels it is enough to have a raster cell size of 256 = 16 x 16 pixels. When outputting a copy of an image on a printer or printing equipment, the raster lineature is selected based on a compromise between the required quality, equipment capabilities and parameters printed materials. For laser printers The recommended lineature is 65-100 Ipi, for newspaper production - 65-85 lpi, for book and magazine production - 85-133 lpi, for artistic and advertising works– 133-300 lpi. When printing images with overlapping rasters, such as multicolor images, each subsequent raster is rotated by a certain angle. Rotation angles are considered traditional for color printing: 105 degrees for blue printed form, 75 degrees for magenta, 90 degrees for yellow and 45 degrees for black. In this case, the raster cell becomes oblique, and a resolution of 16x150=2400 dpi is no longer sufficient to reproduce 256 tone gradations with a lineature of 150 lpi. Therefore, for professional-class photographic exposure devices, the minimum standard definition 2540 dpi, providing high-quality rasterization at different raster rotation angles. Thus, the coefficient taking into account the correction for the raster rotation angle for color images is 1.06.

Dynamic range The quality of tone image reproduction is usually assessed by dynamic range (D). This optical density, numerically equal to the decimal logarithm of the reciprocal of the transmittance (for originals viewed “through the light”, such as slides) or the reflectance (for other originals, such as printed prints). For optical media that transmit light, the dynamic range ranges from 0 to 4. For surfaces that reflect light, the dynamic range value ranges from 0 to 2. The higher the dynamic range, the larger number halftones are present in the image and themes better quality his perception.

Graphic Data Formats

TIFF (Tagged Image File Format) The format is designed for storing high-quality raster images (file name extension.TIF). It is widely used and is portable between platforms (IBM PC and Apple Macintosh), provided with support from most graphic, layout and design programs. Provides a wide range color gamut– from monochrome black and white to 32-bit CMYK color separation model. Starting from version 6.0, the TIFF format can store information about masks (clipping paths) of images. The built-in LZW compression algorithm is used to reduce file size.

PSD (PhotoShop Document) Own format programs Adobe Photoshop(file name extension.PSD), one of the most powerful raster storage capabilities graphic information. Allows you to remember the parameters of layers, channels, degrees of transparency, and many masks. 48-bit color encoding, color separation, and various color models are supported. The main disadvantage is that the lack of an effective information compression algorithm leads to a large volume of files.

JPEG (Joint Photographic Experts Group) The format is intended for storing raster images (file name extension.JPG). Allows you to adjust the relationship between file compression rate and image quality. The compression methods used are based on removing “redundant” information, so the format is recommended to be used only for electronic publications.

GIF (Graphics Interchange Format) Standardized in 1987 as a means of storing compressed images with a fixed (256) number of colors (file name extension .GIF). Gained popularity on the Internet thanks to high degree compression. The latest version of the GIF89a format allows you to load interlaced images and create images with transparent backgrounds. Limited possibilities for the number of colors determine its use exclusively in electronic publications.

BMP (BitMap Picture) A raster image storage format developed by Microsoft. Works with BMP format huge amount programs, since its support is integrated into operating Windows systems and OS/2. BMP files can have extensions .bmp, .dib and .rle. The color depth in this format can be 1, 2, 4, 8, 16, 24, 32, 48 bits per pixel, but 2 bits per pixel is not officially supported. In this case, for color depths less than 16 bits, a palette with full-color components with a depth of 24 bits is used. In format BMP images can be stored as is or using some common compression algorithms. In particular, BMP format supports RLE compression without loss of quality, and modern operating systems and software allow you to use JPEG and PNG (these formats are built into BMP as a container).

PNG (Portable Network Graphics) A raster format for storing graphic information using lossless compression using the Deflate algorithm. A relatively new (1995) format for storing images for publishing on the Internet (file name extension .PNG). Three types of images are supported - color with a depth of 8 or 24 bits and black and white with a gradation of 256 shades of gray. PNG was created as free format to replace GIF. PNG is a good format for image editing, even for storing intermediate stages of editing, since image restoration and resaving takes place without loss of quality. Also, unlike, for example, TIFF, the PNG specification does not allow implementation authors to choose which features they are going to implement. Therefore, any saved PNG image can be read by any other application that supports PNG.

EPS (Encapsulated PostScript) A format for describing both vector and raster images in Adobe's PostScript language, the de facto standard in the field of prepress processes and printing (file name extension.EPS). Since the PostScript language is universal, the file can simultaneously store vector and raster graphics, fonts, clipping paths (masks), equipment calibration parameters, color profiles. The WMF format is used to display vector content on the screen, and TIFF is used for raster content. But the screen copy only roughly reflects the real image, which is significant drawback EPS. The actual image can only be seen at the output of the output device, using special programs viewing or after converting the file to PDF format in Acrobat Reader, Acrobat Exchange applications.

PDF (Portable Document Format) Document description format developed by Adobe (file name extension.PDF). Although this format is primarily intended for storing entire documents, its impressive capabilities allow for efficient presentation of images. The format is hardware-independent, so images can be displayed on any device – from a monitor screen to a photographic exposure device. A powerful compression algorithm with controls for the final image resolution ensures compact files while high quality illustrations.

Software tools for creating raster images

Among the programs designed for creating computer two-dimensional painting, the most popular are the company's Painter Fractal Design, FreeHand by Macromedia, and Fauve Matisse. The Painter package has a fairly wide range of drawing and color tools. In particular, it models various instruments(brushes, pencil, pen, charcoal, airbrush, etc.), allows you to imitate materials (watercolor, oil, ink), as well as achieve the effect of a natural environment. In turn, the latest versions of the FreeHand program have rich image and text editing tools, contain a library of special effects and a set of tools for working with color, including multicolor tools gradient fill. Adobe's Photoshop package occupies a special place in the wide class of programs for processing raster graphics. The main controls of the Adobe Photoshop program are concentrated in the menu bar and toolbar. Special group make up dialog boxes– tool palettes.

Palette Brushes controls settings for editing tools. A brush enters editing mode after double-clicking on its image in the palette. Click when pressed CTRL key destroys the brush. Double-click on the free field of the palette to open the formation dialog box new brush, which is automatically added to the palette.

Palette Options serves to edit the properties of the current tool. You can open it not only from the menu bar, but also double click on the tool icon in the toolbar. The composition of the palette controls depends on the selected tool.

Palette Info provides information support display means. It presents: the current coordinates of the mouse pointer, the size of the current selected area, the color parameters of the image element and other data.

Palette Navigator allows you to view different parts of the image and change the viewing scale. The palette window contains a thumbnail of the image with a selected viewing area.

Palette Synthesis Displays the color values ​​of the current foreground and background colors. Sliders on the color bar corresponding color system allow you to edit these parameters.

Palette Catalog contains a set available colors. This set can be downloaded and edited by adding and removing colors. The color tone of the foreground and background is selected from the set. The standard package of the program includes several color sets, mainly from Pantone.

Layers Palette serves to control the display of all layers of the image, starting from the top one. It is possible to determine the parameters of layers, change their order, and operate on layers using different methods.

Channels Palette used to select, create, duplicate and delete channels, determine their parameters, change the order, convert channels into independent objects and formation of combined images from several channels.

Palette Contours contains a list of all created contours. When you convert a path to a selection, it is used to form a clipping path.

Palette Operations allows you to create macro commands - a specified sequence of operations with an image. Macros can be recorded, executed, edited, deleted, or saved as files.

Special group software image processing represent Filters . These are modules plugged into the program, often from third parties, that allow you to process the image according to given algorithm. Sometimes such algorithms can be very complex, and the filter window can have many customizable parameters. Among the filter groups, products from the Kai's Power Tools, Alien Skin, Andromeda and others series are popular.

Drawing tools of raster graphics editors

To create an image using traditional methods, you need to select a drawing tool (this can be felt-tip pens, a brush with paints, pencils and much more). In raster graphics editors, there are similar tools that allow you to change the color of certain groups of pixels.

• Pencil allows you to draw arbitrary thin lines. To draw, you need to move the mouse while holding down the left button.
• Brush allows you to draw arbitrary lines of varying thickness using a “brush” of the selected shape.
• Eraser(a brush that paints with the background color) allows you to erase arbitrary pixels of the image, while the size of the Eraser can be changed.
• Spray allows you to splash “paint” (paint pixels randomly) and thus paint over arbitrary areas. The width of the spray pattern can be adjusted.
• Fill allows you to paint closed areas entirely.
• Inscription allows you to create text areas on pixel images. By placing the cursor inside a text area, you can enter text that becomes part of the pixel image. When creating text, you can select the font typeface, change its size and style.

Raster graphics editors allow you to draw graphic primitives (straight line, curved line, rectangle, polygon and circle) in the drawing field. In a raster graphics editor, a drawn object ceases to exist as an independent element after drawing is completed and becomes just a group of pixels in the image.

• Line allows you to draw a straight line. Before drawing, it is possible to set the type of line (solid, dotted, etc.), its thickness and color using additional menus.
• Curve allows you to draw an arbitrary line and drag it with the mouse to give it the required shape.
• Rectangle allows you to draw a rectangle: click to fix the position of the first vertex, drag the pointer diagonally and fix the position of the second vertex. If you hold down the Shift key while drawing, a square will be drawn.
• Polygon allows you to draw a polygon: successively click to fix the position of the vertices and double-click to fix the position of the last vertex.
• Circle(ellipse) allows you to draw a circle or ellipse: click to fix the position of a point on the oval, drag the pointer diagonally and fix the position of the point opposite to the center of the oval. If you hold down the Shift key while drawing, a circle will be drawn.

Editing an image can be done using three basic operations: copy, move and delete. When you perform a copy operation, the selection is saved in the image and can be pasted into it multiple times. When you perform a move operation, the selection is removed from the image, but can be inserted into it multiple times. The delete operation removes the selected fragment from the image. Before performing each editing operation, you must select an area of ​​the image (a group of pixels) in a raster editor. Typically the following selections are possible:

• selecting a rectangular area;
• selecting an arbitrary area.

There is a primary color, which is used to draw the outlines of the figures, and a background color, which is used to paint the figures. The color picker menu typically contains foreground and background color indicators that indicate current settings. Color selection using the palette menu is limited, as it only contains a few dozen colors. However, graphic editors allow you to use an expanded color palette, in which you can choose from a set of tens of millions of colors. The principle of forming colors in an expanded palette is based on the fact that any shade of color can be obtained by mixing three basic colors in a certain proportion: red, green and blue. This can be done either using the mouse, moving the pointer across the color field, or by entering the intensity values ​​of each base color (in the range from 0 to 255) from the keyboard into the corresponding text fields. In the majority graphic editors you can use the tool to copy colors Pipette. Left-clicking an area with a selected color sets it as the foreground color, and clicking right click- as a background color.

Geometric transformations

Raster images can be subjected to geometric transformations:

• changing the size horizontally and vertically;
• turns clockwise or counterclockwise;
• tilting at different angles;
• reflections in different planes.

Raster editors have a scaling tool that allows you to increase or decrease the scale of the image or drawing on the screen, but does not affect it actual sizes. Typically this tool is called Magnifier.

Advantages of raster graphics

Raster graphics allow you to create (reproduce) almost any drawing, regardless of complexity, unlike, for example, vector graphics, where it is impossible to accurately convey the effect of the transition from one color to another without loss in file size.

• Prevalence - raster graphics are now used almost everywhere: from small icons to posters.
• High speed of processing complex images if scaling is not needed.
• Raster representation of an image is natural for most graphic input/output devices, such as monitors (with the exception of vector ones), dot matrix and inkjet printers, digital cameras, scanners, and cell phones.

Impossibility of perfect scaling. Raster images do not scale well; you can reduce the image, but it is impossible to enlarge it without losing quality (quality loss includes a noticeable increase in image blur after enlarging the image).

Large file size with simple images. The file sizes of raster illustrations grow rapidly with increasing resolution. A photograph intended for home promotion ( standard size 10x15 cm, digitized with a resolution of 200-300 dpi, color resolution 24 bits), takes up about 4 MB in TIFF format with compression mode enabled. A slide digitized with high resolution occupies 45-50 MB. Color separated color image A4 format takes 120-150 MB.

• Inability to print to plotter.

It is customary to use raster graphics to illustrate works that require high precision in the reproduction of colors and halftones. Raster graphics are used for storing and processing halftone images (scanned or originally created on a computer paintings, photographs); in web design. The images used on web pages are usually not large, and they are displayed on the screen by the web browser itself without the use of additional programs.

Raster graphics editors

Raster graphic editors are a means of processing digital photos and scanned images, since they allow you to improve their quality by changing the color palette of the image and even the color of each individual pixel. You can increase the brightness and contrast of old or low-quality photographs, remove minor image defects (such as scratches), convert a black and white image to color, etc. In addition, raster graphics editors can be used for artistic creativity by using various image conversion effects. An ordinary photograph can be turned into a mosaic panel, a painting, a relief image and others. One of the most popular and famous editors is Adobe Photoshop, which allows you to effectively use all the advantages of raster graphics. Its competitor is applications developed under the GNU General license Public License - GIMP. The Windows operating system includes a simple raster graphics editor. Paint. The simplest raster editors include PaintBrush, Paint, Painter, which allow you to directly draw simple raster images. The main class of raster graphics editors is designed for processing ready-made raster images in order to improve their quality and create own images from those already available. Such editors include: powerful programs, How Adobe Photoshop, Corel PhotoPaint, Gimp and others.

Conclusions

Raster graphics refer to types of graphic files in which an image is stored using dots of different colors (pixels) that form columns and rows. Each pixel in such an image has a specific position and color. Storing each pixel requires a certain amount of computer memory. The quality of a raster image depends on the size of the image (the number of horizontal and vertical pixels) and the number of colors that can be specified for each pixel. Raster files usually have a large color depth, so raster graphics files have a large information volume. Raster graphics editors are the best means of representing tone originals, such as photographs, since raster images provide quite high accuracy transfer of gradations of colors and halftones. The color characteristics of raster images lead to huge graphic file sizes and distortion when scaling. Processing such an image, such as resizing it, may result in loss of small parts, graininess and uneven object boundaries. Among raster graphics editors, there are quite easy-to-use ones, such as Paint, and more complex, powerful professional programs like Adobe Photoshop. Raster images are also created by scanning programs.

So, let's look at the most common graphic formats used to create images, photographs, animations, etc.

BMP(Windows Device Independent Bitmap). Windows native format. It is supported by all graphic editors running this operating system. It is used to store bitmap images intended for use in Windows and this is where its scope ends. Using BMP for purposes other than Windows is a fairly common mistake.

GIF(CompuServe Graphics Interchange Format). The hardware-independent GIF format was developed in 1987 (GlF87a) by CompuServe for transmitting raster images over networks. In 1989, the format was modified (GIF89a), support for transparency and animation was added. GIF uses LZW compression, which makes it possible to compress files with a lot of uniform fills (logos, inscriptions, diagrams) well.

JPEG(Joint Photographic Experts Group). Strictly speaking, JPEG is not a format, but a compression algorithm based not on searching for identical elements, but on the difference between pixels.

The higher the compression level, the more data is discarded, the lower the quality. Using JPEG you can get a file 1-500 times smaller than BMP! Initially, CMYK was not included in the format specifications; Adobe added support for color separations, but CMYK JPEG causes problems in many programs.

JPEG compresses photo-quality raster images better than logos or diagrams.

TIFF, TIF(Target Image File Format). Hardware independent TIFF format, one of the most common and reliable today, it is supported by almost all programs on PC and Macintosh in one way or another related to graphics. The entire range of color models is available to him from monochrome to RGB, CMYK and additional Pine colors. TIFF may contain clipping paths, alpha channels, layers, and other additional data.

In the TIFF format, it is possible to save using several types of compression: JPEG, ZIP, but, as a rule, only LZW compression is used.

EPS(Encapsulated PostScript). The format uses a simplified version of PostScript: it cannot contain more than one page in one file, and does not save a number of printer settings. EPS is designed for transferring vectors and rasters to publishing systems and is created by almost all programs that work with graphics. It makes sense to use it only when the output is carried out on a PostScript device. EPS supports all color models needed for printing.

EPS has many varieties, depending on the creator program. The most reliable EPS are created by programs produced by Adobe Systems: Photoshop, Illustrator, InDesign.

QXD(QuarkXPress Document). Working format of the well-known layout program QuarkXPress. The package is characterized by stability, speed and ease of use. The main, never defeated competitor of Adobe Systems continues to exist now in its fifth reincarnation. It should also be noted that two previous versions of QuarkXPress 3.x and QuarkXPress 4.x are still in use. The special ideology of the package lies in its ability to adapt to any layout designer’s tasks. After all, the main functions are performed by special extensions (Xtensions), of which there are more than Plug-ins for Photoshop.

RM(Page Maker). Adobe Systems layout program format. An extremely simple package in terms of capabilities. It was intended primarily for the transition from manual layout to computer layout with minimal costs for staff training. It became widespread among us thanks to timely Russification and, again, ease of learning for beginners. Currently, development of the package has been stopped.

ID(InDesign). Code name “Quark Killer” A follower of RM, designed to squeeze out competitors in the publishing market, primarily Quark. A hodgepodge of solutions borrowed from other layout packages did not lead to the expected result. ID is an extremely clumsy and inconvenient package, which turned out to be the killer only of its progenitor RM, and then because of the cessation of development of the latter.

The only advantages include a built-in PostScript interpreter and apparent ultra-compatibility with other Adobe products.

PDF(Portable Document Format) - proposed by Adobe as a platform-independent format for creating electronic documentation, presentations, transferring layout and graphics over networks.

PDF files are created by converting from PostScript files or using the export function of a number of programs. The format was originally designed as a means of storing electronic documentation. Therefore, all data in it can be compressed, and in different ways: JPEG, RLE, CCITT, ZIP. PDF can also retain all of the output device information that was in the original PostScript file.

Adobe PostScript- page description language. It was created in the 80s to implement the WYSIWYG (What You See is What You Get) principle. Files in this format are actually a program with commands to execute for the output device. Such files contain the document itself, associated files, fonts used, as well as other information: color separation boards, additional boards, screen lineature and halftone dot shape for each board, and other data for the output device.

Data in a PostScript file is usually written in binary encoding. Binary code takes up half the space of ASCII.

CDR- format of the popular vector editor CorelDraw. The package gained its popularity and distribution due to its apparent ease of use and interactive special effects (lenses, transparencies, non-standard gradients, etc.). The wide capabilities of this program, in terms of effects, are explained by the richer internal page description language than that of Adobe products, using PostScript. This is precisely the main disadvantage of CorelDraw. PostScript with Korelov special effects is often a headache for printing houses and prepress bureaus.

CCX- vector graphics format from Corel. It is not supported by anything other than CorelDraw. Unsuitable for printing and the Internet. The advantages include only a small volume of files saved in this format and the presence of many excellent cliparts.

Vector graphics are a mathematical description of objects relative to an origin. Thus, to display a straight line, the coordinates of only two points are required. For a circle - coordinates of the center and radius, etc.

Graphic formats can contain a lot of additional information: alpha channels, paths, color model, raster lineature and even animation. The choice of format for printed products primarily depends on the output device. Phototypesetting machines operate under the PostScript language. Therefore, for printing, the main data storage formats are TIFF and EPS. Accordingly, the format is raster and vector graphics. IN lately PDF (Portable Document Format) is gaining momentum.

TIFF Only suitable for transmitting raster graphics. This format allows you to store a lot of useful information: alpha channels, color model, paths and even layers (if using Adobe Photoshop 6-7). However, to increase the reliability of the output, many prepress bureaus do not recommend leaving additional channels and layers. For reinsurance, if it is not possible to consult with printing house, it’s also better to turn off compression. You should also not save text labels and vector graphics in TIFF format. Even with a resolution of 300 dpi, they will look like a sawtooth effect when printed. In order to avoid such defects, the EPS format is provided, which allows you to contain raster and vector graphics, fonts and other useful information. However, quite often we encounter this curious misconception: when opening an EPS file (created using Illustrator or Corel Drow) with the raster graphics program Photoshop, users continue to firmly believe that they are still working with vector graphics. No, my dears, no matter what format you save it in, the output you will get is only a raster and nothing more. By opening any file with vector graphics in Photoshop, you thereby rasterize it, that is, turn it into raster format. The only exception is EPS created directly in Photoshop versions 6-7. Fonts and vector primitives, in this case, will remain vector in the output. This format is called Photoshop EPS. There are quite a few varieties of EPS, they differ in the presence of preview images, composite or separated images, encoding and compression. But they all agree on one thing - EPS is based on the PostScript page description language, which in turn is a standard for printing output devices. Therefore, it should be taken into account that all files in other formats, such as CDR and CCX, must be forcibly converted to PS. At the same time, commands from one language are not always adequately translated into another, and the result of such a conversion can be, at best, damaged films, or, at worst, the entire circulation. Therefore, the attitude of printing house workers towards such formats and programs is appropriate. However, this does not mean that everyone should prepare vector graphics in Illustrator and raster graphics in Photoshop; it’s just that when preparing graphics in another package, you need to limit your flight of “fantasy” and especially carefully check the output files for PostScript errors. Unlike other packages, the package Adobe Illustrator was designed as an interface to the PostScript language and does not need to convert its files in order to obtain a format understandable for the output device. In the ninth and tenth versions of Illustrator, the base format is PDF, which is also not a problem for output, because it is essentially “refined” EPS. All previous versions are based on PostScript.

We should not forget about fonts. Often in EPS file Only the names of the fonts appear and others are substituted in the output, which in no way corresponds to the designer’s intention. Therefore, fonts must be converted to curves, either embedded in a file, or attached as separate files.

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4. What are the main types of software?
5. What is the main difference between operating system and application programs?

in their memory. Test on the topic “Computer Graphics” Option 2 2 Multimedia is A) receiving moving images on the display; B) application program for creating and processing drawings; B) combining high-quality images with realistic sound; D) the field of computer science that deals with the problems of drawing on a computer. 3Select the correct sequence of stages in the development of computer graphics: a) The appearance of graphic displays; b) Symbolic graphics; c) The emergence of plotters; d) The emergence of a color printer. A) a, c, d, b; B) b, c, a, d; C) b, a, c, d; D) a, b, d, c. 3. The creation of arbitrary drawings and drawings is carried out by A) scientific graphics; B) design graphics; B) business graphics; D) illustrative graphics. 4. What computer device carries out the sound sampling process? A) sound card; B) columns; B) headphones; D) processor. 5. A raster image is... A) a mosaic of very small elements - pixels; B) a combination of primitives; B) color palette. 6. A point on the graphic screen can be painted in one of the colors: red, green, brown, black. How much video memory will be allocated to encode each pixel? A) 4 bits; B) 2 bytes; B) 4 bytes; D) 2 bits; D) 3 bits. 7. The GR tool is: A) Line; B) color; B) sprinkler; D) drawing. 8. A graphic primitive is: A) line; B) eraser; B) copying; D) color. 9. To obtain a 4-color image, you need to allocate A) 1 byte for each pixel; B) 1 bit; B) 2 bytes; D) 2 bits 10. A discrete signal is...A) a digital signal; B) the number of measurements made by the device in 1 second; B) a value that continuously changes over time physical quantity; D) a table with the results of measurements of a physical quantity at fixed points in time. 11. At what sampling frequency is sound reproduction more accurate? A) 44.1 kHz; B) 11 kHz; B) 22 kHz; D) 8 kHz. 12. What are the disadvantages of raster graphics compared to vector graphics? A) Large volume graphic files. B) Photographic image quality. B) Ability to view images on the screen graphic display. D) Distortions when scaling. 13.What are the disadvantages of an LCD monitor? A) light weight; B) darkening when the viewing angle changes; B) absence of e/m radiation; D) small volume. 14The code for green color is 1011. How many colors are in the palette? 15Find the volume of the recorded quad audio file if the recording lasted 4 minutes, using a 16-bit audio encoding depth and a sampling frequency of 32 kHz. 16To store a raster image measuring 64 by 64 pixels, 512 bytes of memory were allocated. What is the maximum possible number of colors in the image palette? 17 During the raster conversion process graphic file the number of colors decreased from 512 to 8. How many times did the information volume of the file decrease?