Graphics application format. What graphic file formats (picture formats) are there and in what programs can they be opened?

As is known, depending on the method of image formation on the monitor screen, computer graphics are usually classified into several types:

• raster
• vector
• fractal
• three-dimensional

I think the reader already knows all this. Therefore, today we will consider the most common and popular raster graphics formats. In future publications I plan to describe other types of file formats computer graphics, in particular vector. Having described these formats, I will give my recommendations for them. practical use in everyday life, i.e. what format for what and where to use

Basics of raster graphics

Raster graphics is a graphic represented on a computer as a set of dots (pixels). Each pixel contains color information. The pixel size is very small, so the human eye perceives the entire image without dividing it into pixels.

For raster graphics important characteristic is the resolution of the image. The same picture can be presented with the best and worst quality in accordance with the number of points (pixels) per unit length.

Permission— number of points per unit of measurement.

dpi (dots per inch)— number of dots per inch.

ppi (points/pixels per inch)- pixels per inch.

Pixel— raster point of the screen image. All images are divided into dots. Pixel is the smallest point. The image can no longer be divided. In addition, a pixel is a dot of one color; it is impossible to color half a pixel one color and the other half another.

Don't confuse image resolution, monitor resolution, and printer resolution. These are different things.

Having remembered the basics of raster graphics, let's move on to a description of raster graphics storage formats.

Image storage formats in raster graphics

File Format- method of saving electronic parts, of which it consists computer file. Various formats organize saving files in different ways. Consider everything existing formats I won’t do raster graphics (and I couldn’t), we’ll consider only the most common and popular ones.

BMP(Bit Map - bit carat). This format initially used the simplest encoding - pixel by pixel (the most wasteful), which was done sequentially in lines, starting from the lower left corner of the graphic image. Files of this format were included in the first versions Windows. This format used only 256 colors, i.e. a pixel is represented by only one byte. Later, the format began to be used to save full-color images. Format BMP- one for standard raster graphics formats.

TIFF (Taged Image File Format)- a standard format in topographic graphics and publishing systems. TIFF files provide better print quality. Due to its large size, this format is not used when creating Web sites and publishing on the Internet.

Format TIFF is one of the most universal and widespread raster graphics formats. It was created as a cross-platform universal format for color images. Working with it is supported by almost all programs for working with bitmap graphics. Can store graphics in monochrome, in RGB And CMYK color representations.

The format includes internal compression. It has an open architecture - it is possible to declare information about the type of image in the header, i.e. versions of it can be used in the future to present new developments. Accompanying information of transmitted images (signatures, etc.) is also saved in the format. Image format TIFF are stored in files with the extension .tif.

GIF format (Graphic Interchamge Format)- graphic data exchange format, which is used for recording and storing raster graphic images. This format differs from other raster graphics formats in that it has been supported on the Internet for a long time. Uses indexed colors (limited set of colors). This is one of the most common image formats distributed on the Internet and used to create Web sites.

Images in GIF .gif. To the benefits GIF The important thing about images is that the appearance of the image is independent of the browser and platform. Drawings, drawings and images with a small amount of solid colors display best, transparent images and animation sequences (this is a very well-known feature of this graphics format). IN GIF Images are compressed without losing information.

JPEG format (Joint Photographic Expert Group)— designed for storing compressed images. The image compression method it uses was developed by a team of photography experts. The decoding of the abbreviation immediately becomes clear JPEG— a joint group of experts in photo processing.

JPEG is one of the most powerful image compression algorithms. In practice, it is the de facto standard for storing full-color images. Format JPEG was created in order to get rid of the restrictions that were imposed on images created in GIF format.

The algorithm operates on areas of 8? 8, in which the brightness and color changes relatively smoothly. Compression in JPEG carried out by smoothly changing colors in the image. A high compression ratio is provided, the value of which reaches 100 and depends on the permissible level of loss of visual information.

The format is widely used in documents HTML and for data transmission over the network. Saves graphics settings in color representation RGB(usually). Images in JPEG format are stored in files with the extension .jpg.

Programs that work with JPEG, use lossy compression algorithms, they exclude from the image those data that are considered unimportant. Before applying the compression algorithm, the image is divided into rectangular areas. When compressing there is a risk of getting fuzzy, blurry image with distortion of details.

JPEG 2000 format (jp2)

This format was developed to replace JPEG. When saving images with the same compression level, images saved in JPEG 2000, are sharper and take up less disk space. In addition, this format solves the problem with the appearance of defects JPEG, which appeared when saving with a high compression ratio (a lattice of 8 × 8 pixel blocks).

The format is not supported in all browsers, which greatly hinders the spread of this format.

PNG (portable network graphics)- a raster graphics storage format that uses lossless compression. PNG is a free format (unlike GIF), so it is widely used.

It is a very powerful and widely used format on the Internet and other areas of computer graphics.

WMF format

WMF format (Windows Metafile Format)- used to exchange graphic data between OS applications Microsoft Windows . IN WMF files can store both vector and raster images. Images in WMF format are stored in files with the extension .wmf.

PSD and CDR formats

PSD format (PhotoShop Document)— internal format for the package Adobe Photoshop. Allows you to save layers in an image and supports all types of graphics. Images in PSD format are stored in files with the extension .psd.

CDR format— internal format for the company’s software package CorelDRAW. Images and text prepared in the program CorelDRAW V CDR format, stored in files with the extension .cdr.

Recommendations for using different raster graphics formats

Now I will try to move from theory to practice and consider the areas of application of various raster graphics formats depending on their characteristics. The characteristics of the formats are as follows: type of compression used, support transparent colors, the ability to create simple animations, support for line-by-line image output for gradual loading in the browser, and the number of colors used in the image.

Using GIFs

Format characteristics:

• Compression support: lossless (Lempel-Ziv-Welch, LZW)
• Transparency support: Yes
• Animation support: Yes ( distinctive feature of this format)
• Yes (interlaced)
• Number of colors: indexed colors (256 colors)
• all platforms

Recommendations: it is advisable to use this format in Web, for images without smooth color transitions (logos, banners, inscriptions, diagrams). A good type of compression and a small number of supported colors allow you to save space when storing graphics, and can also be used when creating websites for faster loading HTML-pages. Interlaced scanning makes it possible to see and evaluate the downloaded image without waiting for the download to finish. However, the limited range of colors makes this format unsuitable for storing images with smooth transitions, gradients, etc. Mainly used on the Internet.

Using PNG

Format characteristics:

• Compression support: lossless compression (Deflate)
• Transparency support: Yes
• Animation support: Yes(APNG)
• Interlaced display support: Yes (two-dimensional interlacing)
• Number of colors: Deep Color
• Compatibility with other platforms: all platforms

Recommendations: the most advanced compression algorithm in PNG allows you to save files smaller in size than in GIF. The ability to use absolutely any color and the use of transparency make this format a leader in terms of use in Web. I would recommend using it instead GIF. Scope of application - used in design Web-sites, image editing, etc. This is a universal format with a great future.

Using JPEG

Format characteristics:

• Compression support: lossy compression
• Transparency support: absent
• Animation support: absent
• Interlaced display support: Yes (Progressive JPEG)
• Number of colors: True Color (RGB and CMYK models)
• Compatibility with other platforms: all platforms

Recommendations: this format should be used for storage large quantity images (photos) on the hard drive, which will significantly save its working space (thanks to the excellent type of compression). It needs to store large-sized photographs with a lot of smooth transitions. Small size of final files allows efficient use JPEG for publishing photos on the Internet. But you should not save the same images in JPEG several times - this will lead to defects and “damage” the image.

Using TIFF

Format characteristics:

• Compression support: supports the ability to apply different compression algorithms (depending on the image being saved)
• Transparency support: absent
• Animation support: absent
• Interlaced display support: absent
• Number of colors: 8, 16, 32 and 64 bpc (Lab, RGB and CMYK models)
• Compatibility with other platforms: all platforms

Recommendations: this powerful format is used in printing, publishing systems, etc. Files in this format are stored for future printing. TIFF Used to store scanned images, faxes, etc. illustrations.

Using BMP

Format characteristics:

• Compression support: It is possible to use lossless compression (Run Length Encoding, RLE)
• Transparency support: absent
• Animation support: absent
• Interlaced display support: absent
• Number of colors: RGB model, 24-bit color depth
• Compatibility with other platforms: Windows only

Recommendations: This format is not suitable for use in Web, typography and even for storing images (due to the lack of image compression). Used only because it is "embedded" in the OS Windows default.

Conclusion

I hope this article helped you understand a little about the variety of raster graphics formats. My recommendations will help you decide on the choice of format for storing graphics. In short, in JPEG store photos in GIF- banners and logos (but it is advisable to gradually move on to PNG), A TIFF used to prepare documents for printing.

Lecture No. 3. Formats graphic files

Graphic file formats. BMP, TIFF, JPEG, GIF, PNG and other formats. Characteristics and application of various formats. Methods for presenting graphical information within a file. Format conversion.

Graphic file formats

In computer graphics, at least three dozen file formats are used to store images. But only some of them are used in the vast majority of programs. As a rule, raster, vector, and three-dimensional image files have incompatible formats, although there are formats that allow you to store data of different classes. Many applications are focused on their own “specific” formats; transferring their files to other programs forces you to use special filters or export images to a “standard” format.

BMP (Windows Device Independent Bitmap). The BMR format is a native Windows format, it is supported by all graphic editors running under its control. A huge number of programs work with the BMP format, since its support is integrated into the Windows and OS/2 operating systems. BMP files can have extensions .bmp, .dib and .rle. Additionally, data in this format is included in binary RES resource files and PE files.

The BMP format can save images with a color depth (the number of bits that describe one pixel in the image) of 1, 4, 8, and 24 bits, which corresponds to a maximum number of usable colors of 2, 16, 256, and 16,777,216. The file can contain a palette that defines the colors , different from those accepted in the system.

TIFF(Tagged Image File Format). The format is intended for storing raster images high quality(file name extension.TIF). TIFF is a hardware-independent format; it is supported by almost all programs on PC and Macintosh that are somehow related to graphics. TIFF is the best choice when importing raster graphics into vector programs and publishing systems. It has a full range of color models available from monochrome to RGB, CMYK and additional Pantone colors. TIFF can save layers, clipping paths, alpha channels, and other additional data.

TIFF has two varieties: for Macintosh and PC. This is because Motorola processors read and write numbers from left to right, while Intel processors read and write numbers the other way around. Modern programs can use both formats without problems.

The native program for this Photo-Styler format is currently “discontinued”, but the format continues to develop and be supplemented with new features. Letraset has introduced a shortened version of the TIFF format called RIFF (Raster Image File Format).

In the TIFF format, LZW, JPEG, and ZIP compression can be used. A number of older programs (eg QuarkXPress 3.x, Adobe Streamline, many text recognition programs) cannot read compressed TIFF files, but if you are using newer software there is no reason not to use compression.

TIFF, despite all the compression algorithms, is still the most “weighty” raster format, so it is not suitable for use on the Internet.

PSD(PhotoShop Document). Own format Adobe programs Photoshop (file name extension.PSD), one of the most powerful in terms of storage capabilities for raster graphic information. Allows you to remember the parameters of layers, channels, degrees of transparency, and many masks. Supports 48-bit color encoding, color separation and various color models. The main disadvantage is that the lack of an effective information compression algorithm leads to a large volume of files. Doesn't open in all programs.

PCX. The format appeared as a format for storing raster data in the PC PaintBrush program from Z-Soft and is one of the most common (file name extension.PCX). The inability to store color-separated images, insufficient color models and other limitations led to the loss of popularity of the format. Currently considered obsolete.

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

The JPEG file format was developed by C-Cube Microsystems as effective method Storing images with high color depth, such as those obtained by scanning photographs with many subtle shades of color. The biggest difference between JPEG and other formats is that JPEG uses a lossy compression algorithm. 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 noticeable.

JPEG is a compression algorithm based not on searching for identical elements, as in RLE and LZW, but on the difference between pixels. Data encoding occurs in several stages. First, the graphic data is converted to a LAB color space, then half or three-quarters of the color information is discarded (depending on the implementation of the algorithm). Next, blocks of 8x8 pixels are analyzed. For each block, a set of numbers is formed. The first few numbers represent the color of the block as a whole, while subsequent numbers reflect the subtle renderings. The range of details is based on human visual perception, so large details are more noticeable.

In the next step, depending on the quality level you choose, a certain portion of the numbers representing fine details are discarded. The final step uses Huffman coding to more efficiently compress the final data. Data recovery occurs in reverse order.

Thus, 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! The format is hardware independent, fully supported on PC and Macintosh, but it is relatively new and is not understood by older programs (before 1995). JPEG does not support indexed color palettes. Initially, CMYK was not included in the format specifications; Adobe added support for color separation, but CMYKJPEG causes problems in many programs. The best solution is to use JPEG compression in Photoshop EPS files, which is described below.

There are JPEG subformats. Baseline Optimized - files are slightly better compressed, but are not readable by some programs. JPEG Baseline Optimized is designed specifically for the web and all major browsers support it. Progressive JPEG is also designed specifically for the Web, its files are smaller than standard ones, but slightly larger than Baseline Optimized. The main feature of Progressive JPEG is its support for analogue interlaced output.

From the above, the following conclusions can be drawn. JPEG compresses photographic-quality raster images better than logos or diagrams - they have more halftone transitions, and unwanted interference appears among monochromatic fills. Large images for the web or with high printed resolution (200-300 or more dpi) are compressed better and with less loss than with low resolution (72-150 dpi), because in each 8x8 pixel square, the transitions are softer, due to the fact that there are more of them (squares) in such files. It is undesirable to save any images with JPEG compression where all the nuances of color rendering (reproduction) are important, since color information is discarded during compression. Only the final version of the work should be saved in JPEG, because each resaving leads to more data loss (discarding) and turning the original image into mush.

GIF (GraphicsInterchangeFormat). Hardware independent GIF format was developed in 1987 (GIF87a) 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.

GIF allows you to record an image “through a line” (Interlaced), thanks to which, having only part of the file, you can see the entire image, but with a lower resolution. This is achieved by writing and then loading, first 1, 5, 10, etc. lines of pixels and stretching the data between them, the second pass is followed by 2, 6, 11 lines, the image resolution in the Internet browser increases. Thus, long before the file is downloaded, the user can understand what is inside and decide whether to wait until the entire file is downloaded. Interlaced notation slightly increases the file size, but this is usually justified by the acquired property.

In GIF, you can set one or more colors to be transparent; they will become invisible in Internet browsers and some other programs. Transparency is provided by an additional Alpha channel saved with the file. Besides GIF file may contain not one, but several raster images, which browsers can load one after another with the frequency specified in the file. This is how the illusion of movement is achieved (GIF animation).

The relevance of the concepts implemented in the GIF format has become especially evident due to the increased use electronic publications(in the form of Web pages or Web sites). Despite the ever-increasing capacity of network hardware, and, in particular, modems, the issue of the volume of graphic elements of electronic publications is quite acute. On the one hand, the visibility and effectiveness of an electronic publication largely depends on the quality of graphic elements, and, first of all, on the resolution and color depth of image pixels. Therefore, the desire of developers of electronic publications to use multicolor graphic images is understandable.

On the other hand, the requirements for the compactness of files transmitted over network channels have by no means faded into the background. Large graphic files require a lot of time to load the image into the browser. Therefore, one of the main tasks of professionals in the field of Web design is precisely to find the proper balance between artistry, information content of a Web page and its volume.

GIF is one of the few formats that uses an effective compression algorithm that is almost as good as archiving programs. In other words, GIF files do not need to be archived, as this rarely provides a noticeable gain in volume.

Therefore, the GIF format, whose main advantage is its minimal file size, still retains its significance as the main graphic format of the World Wide Web.

The main limitation of the GIF format is that a color image can only be recorded in 256 color mode. This is clearly not enough for printing.

There are two GIF specifications. The first refers to the GIF87a format, which provides for recording multiple images, and GIF89a, which is focused on storing both text and graphic data in one file.

GIF87 a provided the following GIF file capabilities:

Interlacing. At first, only the “skeleton” of the image is loaded, then, as it is loaded, it is detailed. This allows you to avoid loading the entire graphic file on slow lines in order to get an idea of ​​it.

Compression using the LZW algorithm. This feature of GIF files keeps them among the leaders in terms of smallest file size.

Placing multiple images in one file.

Position of the image on the logical screen. That is, the format made it possible to define a logical screen area for displaying images, and place them in an arbitrary location in this area.

This standard was later extended by the GIF89a specification, which added the following capabilities:

Including comments in the graphic file (not displayed on the screen, but can be read by a program that supports GIF89a).

Controls the delay before changing frames (set in 1/100 of a second, or waiting for user input).

Controls the deletion of the previous image. The previous image can be left, replaced with the background color or with what came before it.

Definition of transparent color.

Text output.

Creation of control blocks by application programs (application-specific extensions). You can create a block inside a GIF file that will be ignored by all programs except the one for which it is intended.

PNG (PortableNetworkGraphics). PNG is a relatively recently developed format for the Web, designed to replace the outdated GIF. Uses Deflate lossless compression, similar to LZW (it was because of the patenting of the LZW algorithm in 1995 that PNG arose). Compressed indexed PNG files are typically smaller than their GIF counterparts, and RGB PNGs are smaller than the corresponding TIFF file.

The color depth in PNG files can be any, up to 48 bits. Two-dimensional interlacing is used (not only rows, but also columns), which, just like in GIF, slightly increases the file size. Unlike GIF, where there is either transparency or not, PNG also supports translucent pixels (then available in the transparency range from 0 to 99%) due to the Alpha channel with 256 shades of gray.

The PNG file records gamma correction information. Gamma is a certain number that characterizes the dependence of the brightness of your monitor screen on the voltage on the electrodes of the kinescope. This number, read from the file, allows you to enter a brightness correction when displaying. It is needed so that a picture created on a Mac looks the same on both a PC and Silicon Graphics. Thus, this feature helps to implement the main idea of ​​WWW - the same display of information regardless of the user's equipment.

PNG is supported in Microsoft Internet Explorer version 4 on Windows and version 4.5 on Macintosh. Netscape added PNG support to its browser in versions starting with 4.0.4 for both platforms. However, support for such important format functions as smooth transitional transparency and gamma correction has not yet been implemented.

PNG and GIF89a have the following properties:

The format is organized as a data stream

"Lossless compression"

Allows you to store indexed images with a palette of up to 256 colors

Progressive display of interlaced data

Transparent color support

Ability to store public and restricted data

Independent of hardware and platform

Advantages of PNG over GIF:

Faster progressive display of interlaced patterns

Expanded user data storage options

PNG features not found in GIF:

Storing full color 48-bit images

Storing 16-bit black and white images

Full Alpha Channel

Contrast pointer

CRC is a method for detecting errors in a data stream

Standard toolkit for developing PNG read-write applications

A standard set of test images to test these applications

GIF features missing from PNG version 1.0:

Ability to store multiple images in one file

Animation

WMF (WindowsMetaFile). Windows operating system vector image storage format (file name extension.WMF). By definition, it is supported by all applications of this system. However, the lack of tools for working with standardized color palettes accepted in printing and other shortcomings limit its use (WMF distorts color and cannot save a number of parameters that can be assigned to objects in various vector editors).

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

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

Encapsulated PostScript format can be called the most reliable and in a universal way saving data. It 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. Like PostScript print files, EPS records the final work, although programs such as Adobe Illustrator and Adobe Photoshop can use it as a working document. 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 necessary for printing, among them, such as Duotone, it can also record data in RGB, clipping path, trapping and raster information, embedded fonts. In EPS format, data is saved on the clipboard (Clipboard) of Adobe programs for exchange among themselves.

You can save a sketch (image header, preview) along with the file. This is a low-resolution copy in PICT, TIFF, JPEG or WMF format that is saved with the EPS file and allows you to see what's inside, since only Photoshop and Illustrator can open the file for editing. All others import the sketch, replacing it with original information when printed on a PostScript printer. On a printer that does not support PostScript, the sketch itself is printed. If you work on Photoshop for Macintosh, save your sketches in JPEG format, other Mac programs save sketches in PICT format. These and JPEG thumbnails cannot be used by Windows applications. If you're working on a PC or don't know where the file will be used, save the sketch in TIFF format (when given the choice).

EPS has many varieties, depending on the creator program. The most reliable EPS are created by programs produced by Adobe Systems: Photoshop, Illustrator, InDesign. Since 1996, Adobe programs have a built-in PostScript interpreter so they can open and edit EPS. Other graphic editors cannot open EPS; moreover, the EPS files they create sometimes turn out to be, to put it mildly, special. Among the most problematic are Quark EPS, created by the Save Page As EPS function, and FreeHand editable EPS, created by the Save As function. You should not particularly trust Corel EPS versions 6 and lower and EPS from CorelXARA. EPS files from CorelDraw 7 and higher still have the problem of adding fields to the Bounding Box (a conditional rectangle in PostScript that describes all objects on the page). Before exporting EPS files from CorelDRAW, CorelXARA and, to a lesser extent, from FreeHand, it is worth converting many program effects (translucent fills, for example) into raster or simple vector objects. Thick outlines (more than 2 pt) may have It also makes sense to convert into objects when the program provides such an opportunity. You can check the EPS file with Adobe Illustrator, if it opens, then everything is in order.

PDF (PortableDocumentFormat). Document description format developed by Adobe (file name extension.PDF). Although this format is primarily intended for storing entire documents, its impressive capabilities allow for efficient presentation of images. The format is hardware-independent, so images can be displayed on any device - from a monitor screen to a photographic exposure device. A powerful compression algorithm with controls for the final image resolution ensures compact files with high quality illustrations. Almost any document or scanned image can be converted to this format. However, to do this, in most cases you will need the full Adobe Acrobat package, which contains Adobe Acrobat Distiller and Adobe Acrobat Writer.

PDF has been an open ISO 32000 standard since July 1, 2008. 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.

You can use the official free program to view Adobe Reader, as well as third-party programs. The traditional way to create PDF documents is a virtual printer, that is, the document as such is prepared in its own specialized program - a graphic or text editor, CAD, etc., and then exported to PDF format for distribution in electronic form, transfer to a printing house, etc. .p.

CDR (CorelDRAW Document). The CDR file format is a vector image or drawing created using CorelDRAW. 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, the CDR file can be opened with Corel Paint Shop Pro.

The format has been known in the past for low stability and poor file compatibility, however, CorelDRAW is extremely convenient to use. The files of these versions use separate compression for vector and raster images, fonts can be embedded, CDR files have a huge working area of ​​45x45 meters, and multi-page is supported.

Ai (AdobeIllustror). Vector image file created in Adobe Illustrator; instead of raster data, consists of paths or lines connected by dots; may include objects, color and text. Ai documents can be opened in Photoshop, but the image will be "rasterized", meaning it will be converted from vector image to raster. The AI ​​format encapsulates and formalizes a subset of the PostScript page description language (PDL) in a structured file. These files are designed to be displayed on a PostScript printer, but may also include a raster version of the image, thereby providing a preview of the image. PostScript in its full implementation is a powerful and complex language and is capable of defining almost anything that can be displayed on a two-dimensional output device, an AI format adapted for storing traditional graphics data: drawings, drawings and decorative lettering. Note, however, that AI files can be very complex. PostScript's power comes largely from its ability to define sequences of operations and then combine them using simple syntactic means. This hidden complexity is sometimes (but not always) minimized in Adobe Illustrator files.

File Conversion

The need to convert graphic files from one format to another may arise for various reasons:

The program the user is working with does not understand the format of his file;

Data that needs to be transferred to another user must be presented in a special format.

Convert files from raster to vector format

There are two ways to convert files from raster to vector format:

1) converting a raster file into a raster object of a vector image;

2) tracing a raster image to create a vector object.

The first method is used in CorelDRAW, which, as a rule, successfully imports files of various raster formats. For example, if a raster image contains 16 million colors, CorelDRAW will display an image that is close in quality to television. However, the imported raster object can become quite large even if source file small. Raster file formats store information quite efficiently, as compression methods are often used. Vector formats do not have this ability. Therefore, a raster object stored in a vector file can be significantly larger in size than the original raster file.

The peculiarity of the second method of converting a raster image to a vector image is as follows. A raster image tracing program (such as CorelTRACE) looks for groups of pixels with the same color and then creates vector objects that correspond to them. Once traced, vectorized drawings can be edited as desired. In Fig. a raster image is shown that converts well to vector. The point is that raster drawings, which have clearly defined boundaries between groups of pixels of the same color, translate well into vector ones. At the same time, the result of tracing a photographic-quality raster image with complex color transitions looks worse than the original.

Original raster image Vectorized image

Original raster image Vectorized image

Converting files from one vector format to another

Vector formats contain descriptions of lines, arcs, shaded fields, text, etc. Different vector formats describe these objects in different ways. When the program tries to convert one vector format to another, it acts like a regular translator, namely:

Reads object descriptions in one vector language,

Tries to translate them into a new format language.

If the translator program reads a description of an object for which there is no exact match in the new format, this object can either be described by similar commands in the new language, or not described at all. Therefore, some parts of the design may become distorted or disappear. It all depends on the complexity of the original image. In Fig. presents one of the possible results of converting a file from one vector format to another. The original image was created in CorelDRAW and consists of the following elements: an imported bitmap image in JPEG format, a frame around the bitmap image, text, and a rectangle with a conical fill.

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, the 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 the minimum file size for transmission 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. Larger number corresponds to better quality, but at the same time increases the file size. 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 minimal 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, precisely because of this 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 Photoshop and supporting all its capabilities. 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 may contain PSD file, greatly increases its weight.

BMP (Bit MaP image)

Bit MaP image (BMP) is a universal raster graphics file format used in the Windows operating system. This format is supported by many graphic editors, including Paint editor. Recommended for storing and exchanging data with other applications. The 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 at the 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 upon and replace the GIF format with a graphics 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 compared to JPEG with the same quality is reduced by another 30%. Speaking in simple language, with the same quality, the file size in JPEG 2000 format is 30% smaller than JPG. When highly compressed, JPEG 2000 does not break the image into squares characteristic of the JPEG format. Unfortunately, at the moment this format is not very widespread and is only supported Safari browsers and Mozilla/Firerox (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.

File formats are the basis of working with digital photographs. will tell you about all the major graphic file formats.

RAW.

A file format containing raw information coming directly from the camera sensor. These files are not processed by the camera's processor (unlike JPG) and contain original shooting information. RAW can be compressed without losing quality.

The advantages of RAW are obvious - unlike JPG, which was processed in the camera and already saved with data compression - RAW gives the widest possibilities for processing photographs and maintains maximum quality.

Note. 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 - Nikon, CR2 - Canon...

JPEG (aka JPG).

This is the most common graphics file format.

JPG 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 the minimum file size for transmission over the network.

JPG 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 minimal 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.

The TIFF format is very popular for storing images. 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 widely supported by graphics applications and is used in the printing industry.

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.

The rights to the TIFF format are currently owned by Adobe. Photoshop can save TIFF without merging layers.

PSD.

The PSD format is used in Photoshop program. PSD allows you to save a raster 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.

The BMP format is one of the first graphic formats. It is recognized by any program that works with graphics, format support is integrated into operating systems Windows and OS/2.

BMP stores data with a color depth of up to 48 bits and a maximum size of 65535x65535 pixels.
At the 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.

The GIF format was created in the early days of the Internet for sharing images. It can store lossless compressed images in up to 256 colors. The GIF format is ideal for drawings and graphics, and also supports transparency and animation.
GIF also supports compression without loss of quality.

PNG.

The PNG format was created to both improve upon and replace the GIF format with a graphics 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.

JPEG 2000 (or jp2).

New graphic format, created to replace JPEG. For the same quality, JPEG 2000 file size is 30% smaller than JPG.

When highly compressed, JPEG 2000 does not break the image into squares 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).

1. Small size, which is achieved by a limited color range - no more than 256 colors.
2. Transparent background.
3. Animation.

1. The best data compression - compresses raster images not only horizontally, but also vertically.
2. Supports color photographic images up to and including 48-bit.
3. 256 levels of transparency.

1. Full color palette.
2. High-quality transparency allows you to overlay the design on any background

Vector graphics

OTHER FORMATS

PostScript

WHICH FORMAT SHOULD I CHOOSE?