Today we will talk about image formats, their features and distinctive features. Many of us know that images come in different formats, but not everyone understands why there are so many of them and what their distinctive features are.

Any image stored on a computer has its own graphic format. Each of the graphic formats has its own properties and purpose. Today there are a huge number of graphic formats. We will consider most of the graphic formats based on one of the most popular graphic editors, Adobe Photoshop. Why Photoshop, it’s simple, this graphic editor has the largest number of formats.

But in addition, we will try to analyze other widely known image formats.

So let's get started:

PSD- This is a proprietary format of the Adobe Photoshop program, it allows you to save all the work done on the image. Namely transparency, layer blending modes, shadows, layers, layer masks and all the other little things done with the image. This format is usually used if the image is not completely finished. It is also often used to develop a website layout, since it is convenient to make layout from this file, seeing all the layers and elements. And in all other cases there is no point in using it, since it has a significantly large file size compared to other formats.

TIFF– allows you to save the prepared Photoshop project as accurately as possible. It contains not only pixel information, but also the density of pixels per image when printed in dpi. It can also store several image layers plus channel transparency information. This format was used mainly in printing.

BMP- This is a dot pattern. An image in this format consists of a mass of dots, each of which contains its own color. This format is very large and can be easily compressed by archivers. The quality loss in BMP is not significant, however, it is inferior to TIFF.

JPEG is the most widely used format. It is widely used in digital technology (cameras). The reason for such widespread use is its rather good quality and small file size. But the small size means that image quality is significantly lost. It's all about the image compression algorithm; it consists in the fact that, when compressed, the image significantly loses accuracy. For these reasons, it is not advisable to use this format in printing. But the advantage is that it is convenient to send them by email (e-mail), post them on the Internet and store them on disks.

GIF– Primarily used to produce graphics for the Internet. It is not suitable for saving photographs, as it has a limitation in color reproduction; for the same reasons, it is not suitable for printing. The image of this graphic format consists of dots, which can include from 2 to 256 colors. Limited color rendering and support for transparency make it indispensable for storing images with minimal colors, such as logos. Another feature of the format is the ability to produce animated images. Widely used to create GIF (animated) banners.

EPS– can be called the most reliable and universal format. It is mainly intended for transmission to publishing houses; the format can be created and used by almost all graphic editors. It makes the most sense to use this format only if the output is on a PostScript device.

This format is unique; it supports everything necessary for printing, it can write data in RGB, clipping paths, as well as the use of fonts and more. Initially, EPS was developed as a vector format, but later its raster version appeared - Photoshop EPS.

PNG is a graphic format that recently replaced the Gif format, and has already become very popular due to the fact that it can maintain transparency and translucency, which was not possible in its predecessor GIF. This means that the png maintains translucency in the range from 1 to 99% using an alpha channel with 256 levels of gray. Transparency works as follows: gamma correction information is written to the file. Gamma correction is a certain number of brightness, contrast of the monitor. This number is subsequently read from the file and allows you to adjust the image display by adjusting the brightness.

PICT is a proprietary Macintosh format. The format is capable of including both raster and vector information, text, as well as sound, and uses RLE compression. Bitwise PICT images can have absolutely any bit depth. Vector PICT images, which have all but disappeared from use these days, had unusual line thickness problems and other variations during printing.

The format is used for Macintosh, and when creating certain presentations only for Mac. On regular computers (not Macs), the PICT format is presented with the extension .pic or .pct, read by certain programs, working with this format is often not easy.

PDF– the format was proposed and developed by Adobe as a format for electronic documentation, various presentations and layout for sending it by e-mail. And its design feature was to provide a compact format. For these reasons, all data in pdf can be compressed, and the peculiarity of it is that different types of compression are applied to different types of information, more suitable for these types of data: JPEG, RLE, CCITT, ZIP.

PCX– raster image format. pcx files use a standard color palette, this format has been extended to store 24-bit images. This format is hardware dependent. Designed to store information in a file in the same form as in the video card. To combine this format with older programs, support for the EGA mode of the video controller is required. The compression algorithm is fast and takes up a small amount of memory, but is not very efficient and is not suitable for compressing photographs and detailed computer graphics.

ICO– This format is designed for storing file icons. ico files can be any size, but the most commonly used icons are those with sides of 16, 32 and 48 pixels. Icons with sizes of 24, 40, 60, 72, 92, 108, 128, 256 pixels are also used. Icon data is usually not compressed. Icons come in True Color, High Color, or with a clearly fixed palette. In their structure, ICO files are closest to the BMP format, but differ from bmp in the presence of a mask applied to the background using the bitwise “AND” operation, which makes it possible to implement transparency.

Exclusive OR overlaying the main image can even invert pixels where the background was not masked. And already with Windows XP, 32-bit icons began to be supported - each pixel corresponds to 24-bit color plus an 8-bit alpha channel, which allows for partial transparency of 256 levels. Using the alpha channel, it is also possible to display the icon with smooth edges and also with a shadow, combined with different backgrounds, the icon mask in this case is ignored.

CDR is a vector format image or drawing created using CorelDRAW. This format was developed by Corel for use in the company's own software products. CDR images are not supported by many graphics editors. But this is not a problem, the file can be easily exported using the same CorelDRAW to more common image formats. Images created in CorelDRAW with the CDR extension can also be opened in Corel Paint Shop Pro. For best compatibility, Corel recommends saving files in an earlier version of CorelDRAW CDR format. CDR files of the tenth and earlier versions can be opened using Adobe Illustrator.

A.I. is a vector image format, the name of which comes from the abbreviation of the name of the vector editor AdobeIllustrator. It is supported by almost all graphics programs that are in any way related to vector graphics. Ai is one of the best middlemen for transferring an image from one editor to another. A distinctive and very important feature of the format is its greatest stability and compatibility with PostScript, which is of great value for publishing houses of printing products.

RAW– this is a data format containing raw information (or processed to a minimal extent), created directly by incoming information from the matrix of a camera (video camera, etc.). This format denotes not only photo data, but also the original audio or video data. This format stores all information about the file and has greater potential for photo processing than the JPG format. RAW preserves the highest possible quality. Data in RAW files can be uncompressed, losslessly compressed, or lossily compressed.

RAW files from a number of camera manufacturers have their own extension format, such as Canon - CR2, Nikon - NEF. Many others have the DNG format proposed by Adobe, these are companies such as Leica, Hasselblad, Samsung, Pentax, Ricoh. If Photoshop does not have a raw camera for your camera, then the files will not open; it was created for these purposes by Adobe.

SVG– Scalable Vector Graphics format. The format was created by W3C. According to the specification, it was created to describe two-dimensional vector and mixed vector/raster graphics in XML. Includes three types of objects: shapes, images, and text. Supports still, animated and interactive graphics. You can create and edit both in text editors by editing the code, and in any graphic editor for vector graphics (Adobe Illustrator, Inkscape, CorelDRAW, Corel SVG Viewer). SVG is an open standard and is not proprietary.

Some of the advantages of the SVG format include: Scalability without loss of image quality. Text in SVG is text, not an image, so it can be selected, copied, and is indexed by search engines (when used on a website). The interactivity of the graphics makes it possible to attach your own events to each of the elements. Availability of using raster graphics within a document. Animation that is implemented in SVG using the SMIL language. Compatible with CSS, it allows you to set object properties such as color, background, transparency, etc. SVG easily integrates with HTML and XHTML documents. Reducing the number of HTTP requests. Small file weight compared to raster graphics.

The main question and topic of our article is formats. Among all the wealth of choice, there is no ideal format that would satisfy all possible requirements. Nevertheless, knowing the future fate of the file - printing, the Internet or simply printing on an inkjet printer, you can properly prepare it and, if not guarantee, then at least maintain hope for success.

All graphic information can be divided into two main groups: vector and raster. Fonts occupy a separate niche in vector graphics.

Raster graphics are a two-dimensional matrix (bitmap) consisting of elementary particles - pixels. The main parameters are size and resolution. The size can be expressed in millimeters, inches, pixels, etc., respectively, this parameter characterizes the horizontal and vertical size of the image. The second main parameter - resolution - characterizes the ratio of the number of pixels per square inch (ppi - pixels per inch or dpi - dot per inch). For newspaper printing, raster graphics should be in the range of 120-150 dpi, for high-quality printing with photo output - 250-300 dpi. Large resolution values ​​are usually redundant and do more harm than good, slowing down the output. Screen resolution is considered to be 72 dpi (in printing it is used only for preview).

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 photographic-quality raster images better than logos or diagrams.

TIFF, TIF(Target Image File Format). The hardware-independent TIFF format is one of the most widespread and reliable today; it is supported by almost all programs on PC and Macintosh that are somehow 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 that use 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. Recently, PDF (Portable Document Format) has been 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 (when using Adobe Photoshop 6-7). However, to improve output reliability, many prepress bureaus do not recommend leaving additional channels and layers in the final files. To be on the safe side, if it is not possible to consult with the printing house, it is also better to disable 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 rasterize it, that is, turn it into a raster format. The only exception can be 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, Adobe Illustrator was designed as an interface to the PostScript language and does not need to convert its files to produce 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, only the names of fonts appear in the EPS file and others are substituted during 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.

Brief summary: Graphic data compression methods. Saving images in standard formats, as well as proprietary formats of graphics programs. Convert files from one format to another.

Target: know compression methods for graphic files, be able to distinguish between graphic file formats and understand the advisability of using them when working with various graphics programs.

An image is characterized by the maximum number of colors that can be used in it, that is, have different color depth. There are types of images with different color depths - black and white line, grayscale, indexed color, full color. Some types of images have the same color depth but differ in color model. The image type is determined when the document is created.

Halftone images.

These images contain pixels of the same color but different brightness. Each pixel can take on 256 different brightness values ​​from 0 (black) to 255 (white). This is quite enough to correctly display an image, for example, a black and white photograph.

Any image can be turned into halftone. If the source material is, for example, a color photograph, then it will become monochrome.

Rice. 1.7.

Images with indexed colors

Indexed colors are so called because in this mode, each pixel in the image is assigned an index pointing to a specific color from a special table called a color palette. Indexed palettes do not contain more than 256 colors, but there may be much less. The fewer colors in the palette, the less memory is required to store the color of each pixel and, therefore, the smaller the image file size.

Rice. 1.8.

Full color images

Full-color images have no restrictions on the number of colors and can be represented in more than 16 million shades.

Rice. 1.9.

Graphic file formats

Format- the structure of the file, which determines the way it is stored and displayed on the screen or when printed. The file format is usually indicated in its name, as a part separated by a dot (usually this part is called the file name extension).

Extension- these are several letters or numbers located after the dot in the file name.

For example, the name ending (extension) ".txt" is usually used to denote files containing only text information, and ".doc" - containing text information structured in accordance with Microsoft Word program standards. Files whose contents follow the same format are called single file types.

Graphic file formats determine the method of storing information in the file (raster, vector), as well as the form of storing information (compression algorithm used).

Compression is used for raster graphics files, because... they have a fairly large volume.

Table 1 provides a brief description of commonly used graphic file formats.

Table 1.1. Characteristics of graphic formats

Format	Picture Mode	Type of graphic information	Application
VMR	Indexed colors only	Applique-type drawings containing large areas of solid color.	The format is supported by all applications. Not used in publishing due to the large volume of files.
TIFF	All	Diagram type drawings	A universal format for storing scanned images with color channels. Includes compression schemes to reduce file size. An important advantage of the format is its portability to different platforms. In its traditional form, TIFF can be considered the preferred format for producing layouts aimed at typographic printing and other methods of replication.
PSD	Supports all image types	Any images	It is internal to the Adobe PhotoShop program. The only format in which all document information is saved, including layers and channels. However, it is better to save the finished image in other graphic formats for two reasons. Firstly, the PSD file is much larger in size. Secondly, this format is not imported by layout and object graphics programs.
JPEG	Only full color images in RGB and CMYK models	Full-fledged photographs or examples of artistic graphics, including subtle tints of colors.	Designed for saving point files with compression. Compression using this method reduces the file size from tenths of a percent to a hundred times (the practical range is from 5 to 15 times), but compression in this format occurs with quality losses (within acceptable limits). A very effective compression algorithm has led to the widest distribution of JPEG on the World Wide Web. The use of this format in printing is not recommended.
GIF	Indexed images only	Diagram-type drawings - images have large areas of uniform coloring with clearly defined boundaries; animated images	Designed specifically for transmitting images over global networks. It has the most efficient compression method, which is necessary to reduce image transmission time. The new version allows storing multiple images in one file. This feature is most often used on Web pages. The Web browser displays the images in the GIF file sequentially.
PNG	Supports full color RGB images and indexed images.	Color images with smooth transitions from opaque to transparent areas	The very name of the format, Portable Network Graphics, speaks about its purpose - for transmitting images over networks. It is possible to use a single additional channel to store a transparency mask. Has an effective compression algorithm without loss of information. The format is used on the Web.
EPS	All	Vector graphics, fonts, rasterized images	Used in printing. It is possible to store screening information, contours and calibration curves.

PDF (Portable Document Format) is a format developed by Adobe Systems based on the PostScript language.

Definition 1

PostScript is a language developed specifically for printing, so any printing equipment can process PDF documents.

This feature made the PDF format cross-platform, that is, applicable on any operating system. The PDF format supports various color palettes, allows you to embed both raster and vector images, and includes an electronic signature mechanism to verify the authenticity of documents.

To create PDF files, a virtual PDF printer mechanism is usually used. To use it, you need to download a special program. One such program is FoxitReader. After the standard installation process, a FoxitReader PDF Printer virtual printer icon will appear in the “Devices and Printers” section of the Start menu.

Now a document created in any other program can be converted to pdf format. You can convert documents created in Notepad, MS Word, Paint or other graphic editors. To convert a document you need:

1. Go to the "Print" command, which is usually found in the "File" menu.
2. In the window that opens, find the list of installed printers and select FoxitReader PDF Printer among them.
3. Click the “Print” button.
4. Specify the address on your hard drive where the resulting pdf file should be saved.

TIFF

TIFF (Tagged Image File Format) - designed for storing raster images with a large color depth.

This format is very convenient for scanning, text recognition, faxing and printing products. TIFF allows the use of various color palettes (black and white, RGB, CMYK, CIE Lab) and supports 8, 16, 32 and 64 bits per color channel modes. The TIFF format allows you to store an image either compressed or uncompressed. Images saved in tiff format without compression usually have a large file size.

JPEG

JPEG (Joint Photographic Experts Group) is a raster graphics format that is most often used for storing photographs. Files created in this format can have the following extensions:

• .jpeg;
• .jfif;
• .jpg;
• .JPG;
• .JPE.

The JPEG compression algorithm allows you to compress both lossy and lossless files. It is most convenient to store realistic images with smooth brightness changes in JPEG format. This format is unsuitable for storing drawings, text, and graphics with sharp contrasts because it leads to distortion. Every time a user saves a JPEG file, a compression algorithm is enabled. Therefore, JPEG is not suitable for multi-stage processing. In this case, distortions will accumulate with each save. JPEG cannot be used where even minimal distortion is unacceptable, for example, for storing ultrasound diagnostic results.

CALS

CALS (Computer Aided Acquisition and Logistics Support) is a raster format designed for storing technical graphics and for electronic exchange of graphic data. Images made in CALS format can only be black and white. Compression may or may not be used. This format was developed by the US Department of Defense.

BMP

BMP (Bitmap Picture) is a raster format developed by Microsoft. Support for this format is integrated into Windows OS. Color depth in BMP format Can be 1,2,4,8,16,32,48.

BMP format files can have the following extensions:

• .bmp;
• .dib;
• .rle.

PNG

PNG (Portable Network Graphics) is a raster format that supports lossless compression. The PNG format is well suited for intermediate storage of images during multi-stage processing, because distortion does not accumulate when saving repeatedly. Color depths allowed are 8, 16, 24 and 48 bits.

GIF

GIF (Graphics Interchange Format) is a raster format developed by CompuServe, designed for transmitting graphic information over the network. This format uses lossless compression, but only supports a 256-color palette, which significantly limits its capabilities. An important feature of the GIF format is the ability to animate images.

SVG

SVG (Scalable Vector Graphics standard) is a new graphic standard for vector graphics. This standard is fundamentally different from its predecessors in that the image in it is described by text in the declarative language XML.

For example, to describe an image of a circle centered at coordinates (100,50), with a red fill, a radius of 40 pixels, and a black border 2 pixels thick, you would write the following code:

stroke-width="2" fill="red" />

Note 1

Of course, this does not mean that the user must know XML and describe his images instead of drawing. The user can create images in the traditional way: by drawing on the canvas using various tools. But all of its actions are automatically translated into XML code and saved that way. Since XML is a text standard, images are available for indexing by search engines. *.svg files take up little space and are quickly processed, which makes this format indispensable when working with the web.

CDR

CDR (CorelDraw) is a vector format created by Corel exclusively for use in its own software products.

The format is proprietary (that is, the property of the authors). For this reason, it is not supported by many other programs. Of the free graphic editors, InkScape and sK1 work with this format. Additionally, CDR can be converted to SVG using Uniconvertor software.

A.I.

AI (Adobe Illustrator) is a proprietary vector format developed by Adobe Systems. Supported by most vector editors.

Graphics file format -- a method of representing and arranging graphic data on external media.

Computer graphics formats can be divided into three types: raster, vector and three-dimensional (used for 3D graphics). The most widespread are raster formats; it is with their use that various photographs are saved, as well as other graphic images that can be seen, for example, on websites.

The classification scheme for graphic file formats is shown in Figure 1.

Figure 1 Classification of graphic formats

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. graphic file raster compression

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 of 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 installing 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. Version 8 of Illustrator is capable of loading Photoshop .psd files and using each of the resulting layers. In addition, to use the same filters, the generated vector image can be directly converted into a raster format and further used as an uneditable raster element. Moreover, all this is in addition to the usually available converters from vector to raster format with obtaining the corresponding file.

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.

The main disadvantage of raster graphics is the large amount of memory required to store images. This is explained by the fact that you need to remember the color of each pixel, the total number of which can be very large. For example, one medium-sized photo takes up several Megabytes in computer memory, i.e. as much as several hundred (or even thousands) pages of text.

When using vector graphics, a mathematical description of each graphic object - a geometric primitive (segment, circle, circle...) from which the image as a whole is formed is stored in the computer memory. Based on this data, the corresponding programs will construct the desired figure on the display screen. It is clear that such an image description requires much less memory (10 - 1000 times) than in raster graphics, since it does not have to remember the color of each point of the picture. The main disadvantage of vector graphics is the inability to work with high-quality artistic images, photographs and films. Nature avoids straight lines, regular circles and arcs. Unfortunately, it is with their help (since these figures can be described by means of mathematics, more precisely, analytical geometry) that an image is formed when using vector graphics. Try to describe, using mathematical formulas, paintings by I.E. Repin or Raphael! (But not “Black Square” by K. Malevich!) Therefore, vector graphics are used to create drawings, diagrams, business cards, etc.