Graphic information is stored in a file with the extension . Such images have a number of significant disadvantages


It was last Friday, but it was not possible to write a Friday post under N3. The reason is banal - lack of free time due to the housing issue and a number of other problems. But this Friday there will be a photo for sure. It already exists and was ready for publication yesterday, but I still decided to spend my free evening time on renovation work in the apartment. Therefore, if you haven’t watched it, be sure to watch it and cheer yourself up.

Let's return to the topic of the post, or rather to the question, what picture formats are there? In general the word "picture" I don't like it in relation to photography. But this is exactly how this question sounds very often, so I decided to leave everything unchanged. I'll just make one clarification. Since a photograph is a raster image, this post will only talk about raster graphics formats.

At all graphic formats— a set of rules for processing received graphic data for the purpose of their further storage or editing. As they say in the lines of V. Mayakovsky “All professions are needed, all professions are important”... The same can be said for image formats.

The developers offer a lot raster formats, intended for storing files. Among the most frequently used are the following: BMP, TIFF, GIF, JPEG, PNG, PSD, ICO.So, let's look at some of the pros and cons, as well as the scope of application of the listed raster image formats.

Raster image formats

  • BMP-(abbreviation for Bit Map image) represents standard raster format and has a universal purpose. It is supported by most graphics editors, including the fairly common one Paint. Initially, coding in it was performed by the most in a simple way, By . But this turned out to be wasteful, since each pixel was represented by only one byte. Consequently, only 256 colors became available, which significantly limited the ability to transmit images. Later it was improved somewhat. Bit Map image almost optimal for storing data and sharing it with other similar applications. But, at the same time, it takes up too much memory space, since it is necessary to save the encoding of all image points. File BMP does not support animation and interlacing.
  • TIFF— (from Tagged Image File Format)– universal for publishing systems and topographic graphics. Such raster image formats provide high quality print. They were created to support almost all programs designed to work with bitmap files, so they are compatible with all platforms. Widely used TIFF in printing and publishing. Files (scanned images, illustrations, faxes, etc.) with the extension .tif stored in this powerful format for later color printing, although monochrome printing is also available - in views CMYK And RGB. It is not used for publishing pictures on a computer network or when creating websites, because it is quite large in size. It is also unsuitable for animation.
  • GIF— (according to the first letters of Graphic Interchamge Format)serves for storageraster images in graphicsand for sharing them. It is one of the “oldest” on the Internet and has been in circulation for a long time, despite the fact that it uses indexed colors (in a limited set). Files with the extension.gifwidely used in the design of Web sites. Among the main advantagesGraphic Interchamge Format It is worth mentioning that the type of image does not depend on the underlying platform or the type of browser, and compression occurs without loss of information. This format displays high-quality drawings with a small amount of uniform colors, drawings, transparent pictures and animation.GIFsmall in size, so it loads quickly, which is important when creating HTML pages. But still, the format has a significant drawback - it has a small range of colors, which limits its capabilities when storing images that have smooth transitions.
  • JPEG— (abbreviation for Joint Photographic Expert Group) helps get rid of the flaws that arise when creating and saving images in GIFs. This uses a compression method for photographs or other images. These raster graphics file formats are the most common when storing multi-color pictures. Compressing images (they are stored in files marked .jpg) is performed in a smooth mode, which ensures a high degree of processing and reduces data loss. On the hard drive in JPEG convenient to save a significant number of pictures, in particular large photographs with smooth transitions. This allows you to significantly save disk space. Also using JPEG It is possible to publish photos of quite acceptable quality on a computer network. But it should be taken into account that during compression some of the data is lost, and when saving the same image again, the chances of irreversible loss of information increase. In this regard, the situation is greatly improved by the improved version of the format - JPEG 2000. True, it is not supported by all browsers, which slows down its spread.
  • PNG— (portable network graphics) allows you to store raster graphics in a lossless compressed form, and the files are smaller in size than GIF. In format PNG Almost any color, as well as transparency, is available. This circumstance opens up wide possibilities in web design. Now it is constantly popular because it is compatible with all platforms, supports interlaced display, has a significant color gamut, and supports animation.
  • Domestic formats raster graphics PSD (short for PhotoShop Document) are intended for program packages. They support all types of images, as well as their layers during processing. Saved in files marked with extension .psd.

There are others raster graphics formats, which were not discussed in the article, but you can write about them in the comments, without forgetting about the competition!

There are two types of graphic files, raster and vector, which have different formats.

  1. raster graphics files correspond to the formats *.bmp, *.tif, *psd, *.gif, *.png, *.jpg;
  2. vector graphics file corresponds to the formats *.wmf, *.eps, *.cdr, *.ai

Knowledge of file formats is the basis for working with digital photographs. they determine how the information is stored in the file (raster or vector), as well as the form in which the information is stored (the compression algorithm used). Compression is used for raster graphics files, since they are usually quite large. Compressing graphic files differs from archiving them using archiving programs (gag, zip, arj, etc.) in that the compression algorithm is included in the graphic file format.

Basic graphic file formats

RAW

Translated from English - raw. The format used in the photo processing process contains raw information that comes directly from the camera sensor and does not have a clear specification. These files are not processed by the camera's processor (unlike JPG) and contain original shooting information. RAW can be compressed without losing quality. Unlike JPG, which was processed in the camera and already saved with data compression, RAW gives the widest possibilities for processing photographs and preserves maximum quality.

In other words, under RAW format refers to data obtained directly from the matrix without processing.

Different camera manufacturers use different algorithms to create RAW in their cameras. Each manufacturer comes up with its own resolution for its RAW file - NEF, NRW - Nikon; CRW, CR2 – Canon.

JPEG (or JPG)

This is the most common graphics file format. JPEG has earned its popularity due to its flexible data compression capabilities. If necessary, the image can be saved with maximum quality. Or compress it to minimum size file for transfer over the network. When saving a JPEG file, you can specify the degree of quality, and therefore the degree of compression, which is usually specified in some conventional units, for example, from 1 to 100 or from 1 to 10. A larger number corresponds to better quality, but the file size increases. Usually, the difference in quality between 90 and 100 is practically not perceived by eye.

JPEG uses a lossy compression algorithm. What does this give us? An obvious disadvantage of such a system is the loss of image quality every time a file is saved. On the other hand, image compression simplifies data transfer by 10 times. In practice, saving a photo with a minimum degree of compression does not result in any visible degradation in image quality. That is why JPG is the most common and popular format for storing graphic files.

TIFF (Tagged Image File Format)

TIFF format is a format for storing raster graphics. It was originally developed by Aldus in collaboration with Microsoft for use with PostScript. It allows you to save photos in various color spaces (RBG, CMYK, YCbCr, CIE Lab, etc.) and with high color depth (8, 16, 32 and 64 bits). TIFF is used in scanning, faxing, text recognition, printing, and is widely supported by graphics applications. It is possible to save an image in a TIFF file with or without compression. Compression levels depend on the characteristics of the image being saved, as well as on the algorithm used. Unlike JPG, a TIFF image will not lose quality every time the file is saved. But, unfortunately, it is precisely because of this that TIFF files weigh many times more than JPG.

PSD (Photoshop Document)

Photoshop Document (PSD) is an original raster format for storing graphic information using lossless compression, created specifically for Adobe programs Photoshop and supporting all its features. It allows you to save a bitmap image with many layers, any color depth and in any color space. Most often, the format is used to save intermediate or final results of complex processing with the ability to change individual elements. PSD also supports compression without loss of quality. But the abundance of information that a PSD file can contain greatly increases its weight.

BMP (Bit MaP image)

Bit MaP image (BMP) is a universal raster graphics file format used in operating system Windows. This format is supported by many graphic editors, including the Paint editor. Recommended for storing and exchanging data with other applications. BMP format is one of the first graphic formats. It is recognized by any program that works with graphics. BMP stores data with a color depth in this format from 1 to 48 bits per pixel, the maximum image dimensions are 65535 × 65535 pixels. On this moment The BMP format is practically not used either on the Internet (JPG weighs several times less) or in printing (TIFF copes with this task better).

GIF (Graphics Interchange Format)

format for storing raster graphics. The GIF format is capable of storing compressed data without loss of quality in a format of up to 256 colors. Includes a lossless compression algorithm that allows you to reduce the file size by several times. An image in GIF format is stored line by line; only the format with an indexed color palette is supported. Recommended for storage; images created programmatically (diagrams, graphs, etc.) and drawings (such as appliqué) with a limited number of colors (up to 256). Used to place graphic images on Web pages on the Internet.

PNG (Portable network graphics)

A raster format for storing graphic information using lossless compression. PNG was created to both improve and replace the format GIF graphic format that does not require a license for use. Unlike GIF, PNG has alpha channel support and the ability to store an unlimited number of colors. PNG compresses data without loss, which makes it very convenient for storing intermediate versions of image processing. Used to place graphic images on Web pages on the Internet.

JPEG 2000 (or jp2)

A graphic format that, instead of the discrete cosine transform characteristic of JPEG, uses wavelet transform technology, which is based on representing the signal as a superposition of some basic functions - wave packets. As a result of this compression, the image is smoother and clearer, and the file size is reduced by another 30% compared to JPEG at the same quality. Speaking in simple language, with the same quality, the file size in JPEG 2000 format is 30% smaller than JPG. At strong compression JPEG 2000 does not break the image into squares that are characteristic of the JPEG format. Unfortunately, at the moment this format is not very widespread and is supported only by Safari and Mozilla/Fireox browsers (via Quicktime).

WMF (Windows MetaFile)

A universal format of vector graphics files for Windows applications. Used to store a collection of Microsoft Clip Gallery graphics.

CDR (CorelDRaw files)

An original vector graphics file format used in the CorelDraw vector graphics processing system.

AI (AdobeIllustrator files)

An original vector graphics file format used in the AdobeIllustrator vector graphics processing system.

EPS (Encapsulated PostScript)

The format of vector graphics files is supported by programs for various operating systems.

Here are almost all the most common ones graphic file formats, which a self-respecting photographer and designer should know.

Graphic file formats. Raster and vector formats.

TIFF format

TIFF(English Tagged Image File Format) - a format for storing raster graphic images. TIFF has become a popular format for storing images with high color depth. It is used in scanning, faxing, text recognition, printing, and is widely supported by graphics applications.

Structure The format is flexible and allows you to save images in paletted color mode, as well as in various color spaces:

  • Binary (two-color, sometimes called black and white)
  • Halftone
  • With indexed palette
  • CMYK
  • YCbCr
  • CIE Lab

8, 16, 32 and 64 bits per channel modes are supported.

Compression. It is possible to save an image in a TIFF file with or without compression. Compression levels depend on the characteristics of the image being saved, as well as on the algorithm used. The TIFF format allows the following compression algorithms:

  • PackBits (RLE)
  • Lempel-Ziv-Welch (LZW)
  • LZ77
  • JBIG
  • JPEG
  • CCITT Group 3, CCITT Group 4

The CCITT Group 3, CCITT Group 4 algorithms were originally developed for fax networks (hence why they are sometimes called Fax 3, Fax 4). Currently they are also used in printing, digital mapping systems and geographic information systems.

TIFF is a tagged format and uses basic, extended and special tags:

Basic tags form the core of the format and must be supported by all products that implement the TIFF format according to the specification. Support for extended tags, unlike basic tags, is optional.

JPEG format

JPEG(English: Joint Photographic Experts Group, after the name of the developer organization) is one of the popular graphic formats used for storing photographic images. Files containing JPEG data typically have the extensions .jpeg, .jfif, .jpg, .JPG, or .JPE. The JPEG algorithm allows for both lossy and lossless image compression.

The JPEG algorithm is most suitable for compressing photographs and paintings containing realistic scenes with smooth transitions of brightness and color. JPEG is most widely used in digital photography and for storing and transmitting images using the Internet.

On the other hand, JPEG of little use for compressing drawings, text and character graphics where sharp contrasts between adjacent pixels result in noticeable artifacts. It is advisable to save such images in lossless formats such as TIFF, GIF or PNG.

JPEG (as well as other distortion compression methods) doesn't fit for image compression during multi-stage processing, since distortions will be introduced into the images each time intermediate processing results are saved. JPEG should not be used in cases where even minimal losses are unacceptable, for example, when compressing astronomical or medical images.

TO shortcomings compression according to the JPEG standard should include the appearance of characteristic artifacts in restored images at high compression rates: the image is scattered into blocks measuring 8x8 pixels (this effect is especially noticeable in areas of the image with smooth changes brightness), in areas with high spatial frequency (for example, on contrast contours and image boundaries), artifacts appear in the form of noise halos.

However, despite its shortcomings, JPEG received very wide use due to a fairly high compression ratio, support for compression of full-color images and relatively low computational complexity.

PDF format

PDF(English: Portable Document Format) - cross-platform format electronic documents, created by Adobe Systems using several features of the PostScript language. Most often, a PDF file is a combination of text with raster and vector graphics, less often - text with forms, JavaScript, 3D graphics and other types of elements. First of all intended for electronic submission printing products, - a significant amount of modern professional printing equipment can process PDF directly. To view you can use the official free program Adobe Reader, as well as programs third party developers. The traditional way of creating PDF documents is a virtual printer, that is, the document as such is prepared in its own specialized program- graphics program or text editor, CAD, etc. and then exported to PDF format for distribution in electronic form, transfer to a printing house, etc. PDF.

The PDF format allows you to embed the necessary fonts (line-by-line text), vector and raster images, forms and multimedia inserts. Supports RGB, CMYK, Grayscale, Lab, Duotone, Bitmap, several types of raster information compression. It has its own technical formats for printing: PDF/X-1, PDF/X-3. Includes an electronic signature mechanism to protect and verify the authenticity of documents. A large amount of related documentation is distributed in this format.

CALS format

Raster CALS format(English Computer Aided Acquisition and Logistics Support) standard developed by a division of the US Department of Defense to standardize the exchange of graphic data in electronic form, especially in the areas of technical graphics, CAD/CAM and image processing applications.

CALS is a well-documented, if unwieldy, format that attempts to cover a lot of ground. If you are not familiar with US government documents, you may find working with this format quite difficult. The CALS raster format is required in most applications that process US government documents. Since all data has a byte organization, problems like “from which end to break an egg, blunt or sharp,” never arise.

Characteristics of the CALS format

  • Type - Bitmap (bit matrix)
  • Color - monochrome
  • Compression - CCITT Group 4 or no compression
  • Maximum size images - unlimited
  • Multiple images per file - yes, Type II only
  • Platforms - everything

BMP format

BMP(from the English Bitmap Picture) is a raster image storage format developed by Microsoft. Works with BMP format great amount programs, since its support is integrated into the Windows and OS/2 operating systems. 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 the BMP format, images can be stored as is or using some common compression algorithms. In particular, the BMP format supports RLE compression without loss of quality, and modern operating systems and software allow the use of JPEG and PNG.

PCX format

PCX(PCExchange) - a standard for presenting graphic information, a not so popular analogue of BMP, although it is supported by specific graphic editors such as Adobe Photoshop, Corel Draw, GIMP, etc. Currently, it is practically replaced by formats that support better compression: GIF, JPEG and PNG.

Format type- raster. Most files of this type use a standard color palette, but the format has been expanded to accommodate 24-bit images. PCX is a hardware-dependent format. Designed to store information in a file in the same form as in the video card. For compatibility with older programs, the video controller must support EGA mode. This compression algorithm is very fast and takes Not large volume memory, however, is not very efficient, impractical for compressing photographs and more detailed computer graphics. Lossless compression is used. When saving an image, successive pixels of the same color are combined and instead of specifying the color for each pixel, the color of the group of pixels and their number are indicated. This algorithm compresses images well that contain areas of the same color.

Advantages of the format

  • the ability to create a limited color palette (for example, 16 or 256 colors);
  • supported by a large number of applications.

Disadvantages of the format

  • does not support color systems other than RGB;
  • Numerous options, especially when working with colors, can make working with the file impossible;
  • an inconvenient compression scheme may actually increase the size of some files.

PNG format

PNG(English portable network graphics) - a raster format for storing graphic information that uses lossless compression.

Application area

PNG format designed to replace outdated and more simple format GIF, and also, to some extent, to replace the much more complex TIFF format. PNG format positioned first of all for use on the Internet and graphics editing.

PNG supports There are three main types of raster images:

  • Halftone (16-bit color depth)
  • Color indexed image (8-bit palette for 24-bit color)
  • Full color image (48-bit color depth)

The PNG format stores graphic information in compressed form. Moreover, this compression is performed without losses, unlike, for example, JPEG with losses.The PNG format has more high degree compression for files with more colors than GIF, but the difference is about 5-25%, which is not enough for the absolute dominance of the format, since the GIF format compresses small 2-16 color files with no less efficiency.

PNG is good format for image editing, even for storing intermediate stages of editing, since image restoration and resaving takes place without loss of quality.

Animation

There is one feature of GIF that is not implemented in PNG - support multiple image, especially animation; PNG was originally designed to just store one image in one file.

Sun Raster Format

Image format Sun Raster This is the native raster format of Sun Microsystems platforms using the SunOS operating system. This format supports black-and-white, grayscale, and color raster data of arbitrary color depth. The use of color maps and simple Run-Length data compression are also supported. Typically, most images in the SunOS operating system are in the Sun Raster format. This format is also supported by most UNIX image processing programs.

Characteristics Sun Raster format

  • Type - bitmap (bit matrix)
  • Colors - various
  • Compression - RLE
  • Multiple images per file - not supported
  • Platform - SunOS
  • Applications - many UNIX applications

Graphic file formats

Information in the section on Wikipedia materials

Each of us, one way or another, encounters images. Let's look at the issue of understanding this term a little more broadly. After all, image formats include not only graphics (animation, animation, etc.), but also video. We will separately dwell on the issues of file conversion, as well as storage of one or another type of information.

What are image formats?

This is information stored in a file, which is intended for data visualization (displaying it on a playback device such as a monitor, TV, printer, mobile device etc.).

As for the information in the file itself, for the most part it describes the method of visualization, the method of creating a solid static or dynamic image, its size (not to be confused with the size of the file itself), the number and depth of colors and their shades, and so on.

Concept of vector and raster graphics

First, let's look at which image formats are used exclusively in the standard sense of graphics. There should be a clear distinction between vector and raster graphics. These two types are basic.

Vector graphics allows you to visualize an object based on a mathematical description of the set of aggregate elements that make up the image, which are usually called primitives. These include the simplest concepts that are familiar to everyone from school. These are points, lines, curves, circles, polygons, etc.

The advantage of this approach is the ability to describe an arbitrarily large number of individual elements without significantly increasing the final file size. In addition, scalability is very evident here, which allows you to change the size of each individual element or their entire set without losing the quality of the entire image. This descriptive algorithm is suitable mainly for graphics created manually, for example, in some kind of graphics editor. This method is not applicable for photographs.

PCX is a format for storing raster images with a color depth of 24 bits. Compression is very fast, but is not suitable for converting detailed graphics such as photographs.

RAW is a universal format used for images coming directly from digital cameras. We can say about it that this is the best image quality format. It can serve as source material for processing not only images, but also sound. In addition, support for metadata provides enormous potential for processing and applying lossless or lossy compression algorithms of any level. The format is quite specific and requires certain knowledge when working with it.

File formats of specialized graphic editors

Except standard types, we can separately highlight the formats of graphic images used in specialized editors.

PDF is a format that can contain text and graphic data. Developed by Adobe Corporation. This format involves the use of different compression methods for each specific element contained in final file. Today it is universal mainly for technical documentation electronic.

CDR is a vector format of the Corel Draw graphics editor. It can only be processed with this software package. Not supported by other editors, but easily exported to other formats.

AI is an Adobe Illustrator program format supported by most other editors. main feature- highest image stability and full compatibility with PostScript technology. Can be used as an intermediate format when converting from one to another.

PSD is the best image format in Adobe Photoshop software for intermediate editing of complex images. Allows the use of layers and blending modes, but is larger in size compared to other formats. As the final format for saving files, it is used exclusively in the program itself.

Large format images

If we talk about large formats where high detail needs to be taken into account, then it is worth using RAW, TIFF or PSD.

However, many professional photo and video cameras with 20-25 megapixel matrices have their own standards. Most of them are adapted to the most common types of formats. Here everything depends only on the settings of the camera itself. The same applies to mobile devices.

Basic types of video and animation

Now let's briefly look at the video, since it can also, in some sense, be interpreted as an image, or rather, as a set of alternating images (frames). The determining factor here is the frame rate per second (fps) and the size of the image in pixels.

Initially at the dawn of development digital video it was well known to everyone AVI format, which is still used today, since it is a kind of container containing information that has been processed or compressed completely different methods(codecs). A special decoder is required for playback.

A little later these appeared known formats, like WMV, MPG, MKV, MP4, VOB, TS and many others, and the latter can even be considered as TV image formats high resolution, allowing you to play files with HD, Full HD (2k) or Ultra HD (4k) quality standards.

When it comes to animation, the most famous technology today is Flash. Initially, it was the development of Macromedia Corporation, but then it was bought by Adobe and significantly modernized. The format of such files is SWF. It is used mainly for creating small animated videos, computer animation, banners or simple games.

Mobile systems

If speak about mobile systems(smartphones or tablets on Android based, iOS, Blackberry, etc.), then specialized image formats are extremely rare. Mostly standard ones are used computer formats images for both graphics and video. However, without installed codecs and decoders, some types of videos will not play. That is why we will have to solve the problem of converting the source material into another type.

Eg, regular phones only accept 3GP format. Android or iOS recommend using MP4. But overall there are enough options.

Changing basic image settings

Probably everyone understands perfectly well that editing needs to be done using special programs.

The simplest operations of resizing, mirroring, rotating, tilting and others can be performed even in the most primitive Paint editor, which is included with any Windows operating system.

If more complex actions are required, say, changing color, saturation, contrast, editing layers, breaking the image into individual components, etc., then you will have to use professional packages like the aforementioned Corel Draw or Adobe Photoshop.

There are utilities for video editing, for example, Vegas Pro. In addition to standard capabilities, they can use specialized effects and modeling systems that allow you to transfer them to a pre-built mathematical model real picture similar to how the fight between Morpheus and Neo was filmed in the first part of The Matrix.

Format conversion

Conversion (conversion) is carried out using utilities called converters. One of the most prominent representatives - Xilisoft Video Converter, which can convert both graphics and video.

For graphics, you may prefer, for example, ACDSee Ashampoo Photo Commander, Free Image Convert And Resize, or something else. Today you can find a lot of such programs.

The only thing worth paying attention to is the final format and possible loss of quality (image compression formats). When viewing a picture or video on a smartphone or tablet, this will not be so noticeable, but on a television panel the difference will become very noticeable.

Which format is preferable for storing data?

Photos on your computer can be stored in the universal JPG format. When viewing them on a monitor, special clarity is not needed. It's another matter when photographs need to be printed. Here it is better to use original camera formats.

When converting one format to another, sometimes it will be simply impossible to restore the “source”, so when submitting files to the studio, it is not recommended to change their original form. Exception if you have necessary knowledge and do the editing yourself using professional software.

The same goes for video. It all depends on what device it will be viewed on.

Conclusion

Image formats are numerous and varied, including graphics and video. The article discussed the most popular formats. Issues of processing and converting them, choosing software, the format used for storing data, etc., are decided by each user himself.


INTRODUCTION

A graphics format is a way of recording graphic information. Graphics file formats are designed to store images, such as photographs and drawings.

Knowledge of file formats and their capabilities is one of the key factors in computer graphics. Yes, today there is no such kaleidoscope of extensions as in the early 90s, when each image editor manufacturing company considered it its duty to create its own file type, or even more than one, but this does not mean that “everything needs to be saved in TIFF and compressed with JPEG.” Each of the formats established today has undergone natural selection and proven its viability. They all have some characteristic features and the capabilities that make them indispensable in their work.Knowledge of the features and subtleties of technology is important for a modern designer, just as it is necessary for an artist to understand the differences in the chemical composition of paints, the properties of soils, types of metals and rocks.

These are raster graphics, vector graphics, three-dimensional and fractal graphics. They differ in the principles of image formation when displayed on a monitor screen or when printed on paper.

Raster graphics are used in the development of electronic (multimedia) and printed publications. Illustrations made using raster graphics are rarely created manually using computer programs. Most often, scanned illustrations prepared by the artist on paper or photographs are used for this purpose. Recently, digital photo and video cameras have found widespread use for inputting raster images into a computer. Accordingly, most graphic editors designed for working with raster illustrations are focused not so much on creating images, but on processing them. On the Internet, raster illustrations are used in cases where it is necessary to convey the full range of shades of a color image.

Software tools for working with vector graphics, on the contrary, are intended primarily for creating illustrations and, to a lesser extent, for processing them. Such tools are widely used in advertising agencies, design bureaus, editorial offices and publishing houses. Design work based on the use of fonts and simple geometric elements is much easier to solve using vector graphics. There are examples of highly artistic works created using vector graphics, but they are the exception rather than the rule, since the artistic preparation of illustrations using vector graphics is extremely complex.

Three-dimensional graphics are widely used in engineering programming, computer modeling of physical objects and processes, animation, cinematography and computer games.

Software tools for working with fractal graphics are designed to automatically generate images through mathematical calculations. Creating a fractal artistic composition is not about drawing or design, but about programming. Fractal graphics are rarely used to create printed or electronic documents, but they are often used in entertainment programs.

The purpose of this test will be an initial study of graphic files and their formats, information compression methods, as well as an analysis of the work done.

The objective of this test will be to determine whether a graphic format belongs to a specific subtype: vector, raster, complex.

    Information compression methods

Almost all modern graphic file formats use some kind of information compression method, therefore, for better understanding further material, the beginning of this section contains summary these methods.

Information compression methods:

One of the simplest compression methods is the RLE (Run Length Encoding) method. The RLE method works by searching for identical pixels in the same row. If a line, say, has 3 white pixels, 21 black, then 14 white, then using RLE makes it possible not to remember each of them (38 pixels), but to write it as 3 white, 21 black and 14 white in the first line .

The LZW (Lempel-Ziv-Welch) compression method was developed in 1978 by Lempel and Ziv, and later refined in the USA. Compresses data by searching for identical sequences (called phrases) throughout the file. The identified sequences are stored in a table and are assigned shorter markers (keys). So, if there are patterns of pink, orange, and green pixels in an image that repeat 50 times, LZW detects this, assigns a separate number to that set (for example, 7), and then stores that data 50 times as the number 7. The LZW method also , like RLE, performs better in areas of uniform, noise-free colors, it performs much better than RLE at compressing arbitrary graphics data, but the encoding and decompressing process is slower.

The Huffman compression method was developed in 1952 and is used as a component in a number of other compression schemes, such as LZW, Deflation, JPEG. The Huffman method takes a set of symbols and analyzes them to determine the frequency of each symbol. The most frequently occurring characters are then represented in the smallest possible number of bits. For example, the letter "e" is most often found in English texts. Using Huffman encoding, you can represent "e" with just two bits (1 and 0), instead of the eight bits needed to represent the letter "e" in ASCII.

Method CCITT compression(International Telegraph and Telephone Committie) was designed for facsimile transmission and reception. It is a narrower version of Huffman coding. CCITT Group 3 is identical to the fax message format, CCITT Group 4 is the fax format, but without special control information.

    Graphics file formats

      Raster format

Raster images are formed in the process of scanning multi-color illustrations and photographs, as well as when using digital photo and video cameras. You can create a raster image directly on your computer using a raster graphics editor.

A raster image is created using dots of different colors (pixels) that form rows and columns. Each pixel can take on any color from a palette containing tens of thousands or even tens of millions of colors, so raster images provide highly accurate color and grayscale reproduction. The quality of a raster image increases with increasing spatial resolution (the number of pixels in the image horizontally and vertically) and the number of colors in the palette.

The disadvantage of raster images is their large information volume, since it is necessary to store the color code of each pixel.

Let's look directly at the extensions of the raster graphics format:

1) The BMP file format (short for BitMaP) is the native raster graphics format for Windows because it most closely matches the native Windows format in which that system stores its raster arrays. The filename extension most often used in BMP format is BMP, although some files have the extension RLE, which stands for run length encoding. The RLE extension of a file name usually indicates that the file's raster information has been compressed using one of two RLE compression methods that are valid for BMP format files.

IN BMP files Each pixel's color information is encoded at 1, 4, 8, 16, or 24 bits (bits/pixel). The number of bits per pixel, also called color depth, determines the maximum number of colors in an image. An image with a depth of 1 bit/pixel can have only two colors, and with a depth of 24 bit/pixel - more than 16 million different colors.

2) PCX became the first standard graphics file format for storing raster graphics files on IBM PCs. This format, used in the ZSoft Paintbrush program, was used in the early 80s. Microsoft acquired a license and then distributed it along with Microsoft products. The format was later converted into Windows Paintbrush and began to be distributed on Windows. Although the use of this popular format is declining, PCX files, easily recognized by their PCX extension, are still widely used today.

PCX files are divided into the following three parts: a PCX header, raster array data, and an optional color table. The 128-byte PCX header contains several fields, including the image size and the number of bits to encode color information for each pixel. The raster array information is compressed using simple method RLE compression; An optional color table at the end of the file contains 256 RGB color values ​​that define the colors of the image. The PCX format was originally developed for CGA and EGA display adapters and has been modified for use in VGA and true color adapters. The color coding of each pixel in modern PCX images can be done at 1, 4, 8, or 24 bit depth.

3) If PCX is one of the easiest raster graphics formats to decode, then TIFF (Tagged Image File Format) is one of the most complex. TIFF files have the extension TIFF. Each file begins with an 8-byte Image File Header (IFH), the most important element of which, the Image File Directory (IFD), serves as a pointer to the data structure. An IFD is a table for identifying one or more variable length pieces of data called tags; tags store information about an image. The TIFF file format specification defines over 70 different types of tags. For example, one type of tag stores information about the width of the image in pixels, while another stores information about its height. The third type tag stores a color table (if necessary), and the fourth type tag contains the raster array data itself. An image encoded in a TIFF file is defined entirely by its tags, and the file format is easily extensible because additional tag types can be defined to add additional properties to the file.

So what makes TIFF so difficult? On the one hand, writing programs that distinguish between all types of tags is not an easy task. Most TIFF file readers implement only a subset of the tags, which is why a TIFF file created by one program sometimes cannot be read by another. Additionally, programs that create TIFF files can define their own tag types that are meaningful only to them. TIFF file readers can skip tags they don't understand, but there is always the danger that this will affect the appearance of the image.

Another complication is that a TIFF file may contain multiple images, each with its own IFD and set of tags. The raster array data in a TIFF file can be compressed using any of several methods, so in reliable program To read TIFF files there must be decompression tools RLE, LZW (LempelZivWelch) and several others. The situation is further aggravated by the fact that the use of LZW unpacking programs must be carried out in accordance with license agreement with Unisys Corp. for the right to use the LZW algorithm and often for a fee. As a result, even the most best programs TIFF readers often fail when faced with an LZW-compressed image.

Despite its complexity, the TIFF file format remains one of the best for transferring raster arrays from one platform to another due to its versatility, which allows almost any image to be encoded in binary form without losing its visual or any other attributes.

4) Most of the leading graphics professionals dealing with the LZW algorithm face similar legal problems when using the popular cross-platform raster graphics file format GIF (Graphics Interchange Format, pronounced "gif"), developed by CompuServe. GIF files are typically named using the GIF extension, and thousands of them are available from CompuServe.

The structure of a GIF file depends on the version of the GIF specification that the file conforms to. There are currently two versions in use, GIF87a and GIF89a. The first one is simpler. Regardless of the version number, a GIF file begins with a 13-byte header containing a signature that identifies the file as a GIF, the GIF version number, and other information. If the file stores only one image, following the header there is usually a general color table that defines the colors of the image. If several images are stored in a file (the GIF format, similar to TIFF, allows you to encode two or more images in one file), then instead of a general color table, each image is accompanied by a local color table.

5) The PNG (Portable Network Graphic, pronounced "ping") format was developed to replace GIF in order to bypass the legal barriers to the use of GIF files. PNG inherits many of the features of GIF and, in addition, it allows you to store true color images. More importantly, it compresses raster array information using a variant of the highly respected LZ77 compression algorithm (predecessor to LZW), which anyone can use for free.

6) Format JPEG file(Joint Photographic Experts Group - Pronounced "japeg") was developed by C-Cube Microsystems as effective method Storing images with great color depth, such as those produced by scanning photographs with many subtle (and sometimes imperceptible) shades of color. The biggest difference between JPEG and the other formats discussed here is that JPEG uses a lossy (rather than lossless) compression algorithm to compress information. The lossless compression algorithm preserves image information so that the decompressed image exactly matches the original. Lossy compression sacrifices some image information to achieve a higher compression ratio. The decompressed JPEG image rarely matches the original exactly, but very often the differences are so small that they are barely (if at all) detectable.

      Vector format

In this subsection we will look at the most common extensions for vector graphics files.

1) Encapsulated PostScript (EPS) - an extension of the PostScript format, data in which is recorded in accordance with the DSC (English, Document Structuring Conventions) standard, but with a number of extensions that allow this format to be used as a graphic one.

The EPS format was created by Adobe based on the PostScript language and served as the basis for the creation earlier versions Adobe Illustrator format.

In its minimal configuration, an EPS file has a so-called BoundingBox DSC comment - information describing the size of the image. This way, even if the application cannot rasterize the data contained in the file, it has access to the image dimensions and its preview.

QuarkXPress versions 4, 5 and 6 cannot rasterize data from an EPS file, so it uses only a preview in the layout - a small copy of the entire image, which is stored in the EPS file separately from the main data. Adobe InDesign versions CS-CS4 do not have such a limitation. The use of a reduced-quality copy of the image is intended to simplify the display of the image on the screen and, as a result, significantly speed up the work with layout. Preview can be recorded in TIFF or WMF format (PC only) or omitted altogether.

The format is used in professional printing and can contain raster images, vector images, and combinations thereof.

An image recorded in EPS format can be saved in different color spaces: Grayscale, RGB, CMYK, Lab, Multi-channel.

The data structure of an EPS raster file can be written using different methods: ASCII data (text data), Binary data (binary data) and JPEG with different compression rates.

2) WMF (English: Windows MetaFile) - a universal format of vector graphic files for Windows applications. Used to store a collection of Microsoft Clip Gallery graphics. The format was developed by Microsoft and is an integral part of Windows, as it preserves a sequence of hardware-independent GDI (Graphical Device Interface) functions that directly output an image to a given graphics device context (to the screen, to a printer, etc.). Very often, WMF is used implicitly to save an image of a program's output window and restore it later, as well as when transferring information via the clipboard. From MS Windows, writing and reading a file of this format is extremely simple and fast; in other operating systems, support for this format is useless. Some Macintosh programs understand it. On the Macintosh platform, the PICT format plays a similar role.

3) CDR file format - a vector image or drawing created using the CorelDRAW program. This file format was developed by Corel for use in its own software products. CDR files are not supported by many image editing programs. However, the file can be exported using CorelDRAW to other, more common and popular image formats.

Also, CDR file can be opened with Corel Paint Shop Pro. For best compatibility, Corel recommends saving files in CorelDRAW CDR format version 9.0 or earlier.

4) Portable Document Format (PDF) is a cross-platform electronic document format created by Adobe Systems using a number of PostScript language features. Primarily intended for electronic presentation of printed products, a significant amount of modern professional printing equipment can process PDF directly. To view, you can use the official free Adobe Reader program, as well as third-party programs. The traditional way of creating PDF documents is a virtual printer, that is, the document as such is prepared in its own specialized program - a graphics program or text editor, CAD, etc., and then exported to PDF format for electronic distribution, transfer to a printing house and etc.

      Complex format

There are also complex formats that can store both vector and raster information. This DjVu formats, CGM, AI (Adobe Illustrator program format), EPS (Encapsulated PostScript - a professional universal vector-raster format used by all professional graphics programs) and PDF (Portable Document Format - an Adobe Acrobat program format that can contain raster and vector graphics, and also text information).

1) DjVu (from the French déjà vu - “already seen”) - a lossy image compression technology designed specifically for storing scanned documents - books, magazines, manuscripts, etc., where the abundance of formulas, diagrams, drawings and handwritten symbols makes it extremely labor-intensive their full recognition. It is also an effective solution if it is necessary to convey all the nuances of design, for example, of historical documents, where not only the content is important, but also the color and texture of the paper; parchment defects: cracks, marks from folding; corrections, blots, fingerprints; traces left by other objects, etc.

DjVu has become the basis for several libraries of scientific books. A huge number of books in this format are available on file-sharing networks.

The format is optimized for network transmission so that the page can be viewed before the download is complete. A DjVu file can contain a text (OCR) layer, which allows full-text search of the file. In addition, a DjVu file can contain a built-in interactive table of contents and active areas - links, which allows for convenient navigation in DjVu books.

2) CGM (from the English Computer Graphics Metafile) - a format for storing and exchanging graphic data that is not related to CAD.

      3 Dpolygons

The X file format is a file format for storing 3D objects created by Microsoft.

This format stores information about the geometry of a 3D object (vertex coordinates and normal coordinates), texture coordinates, description of materials, paths and names of textures that are used. The hierarchy of objects is stored, the animation is stored, and the bindings of vertices to “bones” with a description of the weights are stored. The X file may not contain any information about the object (for example, the X file may only contain vertex coordinates).

An X file can be text or binary.

At the beginning of the X file there is a header, then there is a description of information about the object. The description of information can be in any order, but the title always comes at the very beginning.

CONCLUSION

No other area of ​​computer application can boast such a variety of file format types as computer graphics. Every more or less reputable software company considers it their duty to create at least some kind of graphic editor, and in addition to it, it goes without saying, they create their own file format in which, as the developers assure, this editor saves the masterpieces created with its help , the best way. As a result of this approach, a situation has arisen where no one is able to cover all the variety of types of existing graphic formats. Graphic files are quite complicated, unlike, say, a simple text file. Over time, the need arose to obtain graphic files with certain requirements. For example, a computer artist needs very high image quality, an ordinary user needs good quality, but not a very large volume, a web designer needs to get a more or less decent image with a minimum volume. But the requirements for file portability between different applications forced the identification of several specific formats, which have become, each in their own area, de facto standards. So, for images on the Internet, in most cases, they use JPEG formats and GIF, for storing images - JPEG, in publishing TIFF reigns, etc.

This is not to say that there are bad formats and there are good ones. Each format has advantages and disadvantages. This article will talk about only some of the graphic formats that are supported by most graphics programs and are used in practice more often than others.

Raster images are saved in a file in the form of a rectangular table, in each cell of which the binary color code of the corresponding pixel is written. Such a file stores data about other properties of the graphic image, as well as its compression algorithm.

Vector images are saved in a file as a list of objects and the values ​​of their properties - coordinates, sizes, colors, etc.

There are quite a large number of both raster and vector graphic file formats. Among this variety of formats, there is no ideal one that would satisfy all possible requirements. The choice of one or another format for saving an image depends on the goals and objectives of working with the image. If photographic accuracy of color reproduction is needed, then preference is given to one of the raster formats. It is advisable to store logos, diagrams, and design elements in vector formats. The file format affects the amount of memory the file occupies. Graphic editor allow the user to independently choose the format for saving the image. If you are going to work with a graphic image in only one editor, it is advisable to choose the format that the editor offers by default. If the data will be processed by other programs, it is worth using one of the universal formats.

There are universal graphics file formats that simultaneously support both vector and raster images.

Bibliography

1. Angel E. Interactive computer graphics. Introductory course at the base. Second edition. M., St. Petersburg, Kyiv, Williams Publishing House, 2001;.

2. Rogers D., Adams J. Mathematical foundations of machine graphics. M., Mir, 2001;.

3. E. V. Shishkin, A. V. Boreskov “Computer graphics: polygonal models”, M., Dialog-MEPhI, 2001.

4. Ivanov V. P., Batrakov A. S. Three-dimensional computer graphics. M., Radio and Communication, 1995;.

5. Gniloy V. Interactive computer graphics. – M.: Mir, 1981.


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