Popular graphic formats. What are the graphic file formats?

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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 in an arbitrarily large number 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 a format best quality Images. 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 in electronic form.

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, such well-known formats as WMV, MPG, MKV, MP4, VOB, TS and many others appeared, 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 computer image formats are used 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 is required complex actions, say, changing color, saturation, contrast, editing layers, breaking the image into separate 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.

Hi all! Everyone has seen pictures on the Internet with such a postscript as bmp, png, jpg or gif(or others)? For example, foto.png or foto.jpg. This graphic files of different formats .

I think I'm not the only one who has wondered what the difference is between these image formats? Let's try to figure it out.

What are image formats and why are they needed?

I won’t clutter the article with too many smart words. Moreover, I myself do not always understand their meaning. Image format in relation to the Internet and computer (by image I mean some kind of graphic information– photographs or drawings) is a way to store and, accordingly, transmit pictures as an element of information.

This is a kind of tool, material or method with which you can save your favorite picture to your computer or transfer your photos from your camera to your PC. In general, it is a way of encoding information.

Let's take a non-computer example. Let's say you decide to preserve your bright image for posterity and order your portrait. But portrait is different from portrait. It can be done different materials, different tools, different techniques. You can contact a photographer, artist or even a sculptor.

(To illustrate my words, I took portraits of Vladimir Semenovich Vysotsky, may those who find this seem inappropriate forgive me)

The photograph can be black and white, color, digital, paper, or in slide form. An artist can make your portrait with paints, pencil, ink, on paper, on canvas, on the wall. A sculptor can make a portrait from plaster, marble, wood, metal...

In general, there are countless options. But any of them will be your portrait.

Same thing with image formats– there are many options.

But they can all be divided into two large groups - raster and vector. But no, there is another group - mixed, or complex, where would we be without them in the modern world :)

We are more interested in raster formats - they are the ones we most often encounter. But a few words need to be said about other groups.

Vector images are based on geometric shapes - points, curves, circles, polygons. Vector images can be enlarged without losing quality. Examples of vector files – svg, cdr, eps. But, to be honest, I have not encountered such formats.

Complex formats, as the name suggests, have features of both vector and raster images. The most famous example of this format is files pdf. Surely everyone has come across them: many electronic books and documents are stored in PDF format.

Raster images

Most common image formats –jpg (jpeg),gif,png,bmp. All of them belong to the raster group.

Raster images, upon closer inspection, consist of small squares - pixels. Therefore, unlike vector images, raster images lose quality at high magnification.

Here is an example of a raster image and its part under magnification.

Do you see how blurred the picture is when zoomed in?

But editing, storing and transmitting raster images is much easier than vector ones. This is very important for ordinary users.

You can work with rasters in such convenient and well-known editors as Adobe Photoshop and Paint.

Characteristics of raster images

One of the disadvantages of raster images is that such files are stored in a compressed form and when they are displayed on the screen or printed, it is impossible to restore the original appearance, the quality suffers to one degree or another. But often these losses are not even noticeable, so don’t get upset and give up using raster graphics. Moreover, by and large, there is no alternative.

The most common image formats are definitely BMP,GIF,PNG, JPEG.

The first group includes BMP, GIF, PNG formats, the second – JPEG. Lossless compression is based on removing redundant information, while lossy compression is based on discarding information that human vision does not perceive.

What are the differences between the image formats bmp, png, jpg, gif

I wrote a lot, a lot above, but still did not answer the question in the title. I don't know if I can answer, but I'll try.

But first, a little illustration. I took one picture and saved it in a separate folder in several formats. The results are clear. Pay attention to the weight of images of different formats.

FormatJPEG (Joint Photographic Experts Group) is a joint group of expert photographers. That was the name of the company that developed this format. Perhaps the most common image format that everyone who has ever sat down at a computer has encountered. Edit jpeg files can be done in almost any graphics editor. During compression, the color of neighboring pixels is averaged. This causes loss in quality. However, the quality of such images is not bad, even good when compared with some other formats.

In addition, jpeg files weigh little. They can easily be sent from phone to phone, by email or posted on the Internet. Also not big size allows you to store a large number of images.

FormatBMP (Bitmap Picture) – raster image. The image quality is excellent because the information is almost not compressed. But the size of such files compared to jpeg is huge.

FormatGIF (GraphicsInterchangeFormat) – graphic data exchange format. Very popular format. It allows you to save animated images. Although it is considered outdated. But judging by the popularity of gifs, this format will not disappear from the scene anytime soon. Of course, gif will not work for photographers - the number of colors in this format is very limited to 256. But on the Internet it is almost the main format. Another important plus is that gif files support transparency mode.

FormatPNG(Portable Network Graphics) – portable network graphics. The format was developed to replace the GIF format. There is even an unofficial decoding of the acronym as “PNG is Not GIF” - PNG is not GIF. This format supports not only transparency, but also translucency from 1% to 99%, which is a big plus. But PNG cannot store multiple images in one file, like GIF. Therefore, it cannot be used to create animated pictures.

Of course, I haven't talked about all image formats. But these are the most common. Therefore, I think my article was useful to you “What is the difference between image formatsbmp,png,jpg,gif".

If the information was interesting and useful, subscribe to announcements of articles on, and also share the article with friends on social networks. Social media buttons are below the article, subscription form is at the link above or in the form at the top left.

Good luck to you in all your noble endeavors!

Lecture No. 3. Graphic file formats

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 store 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 (for example, QuarkXPress 3.x, Adobe Streamline, many text recognition programs) cannot read compressed files TIFF, however, if you are using new 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). Adobe Photoshop's own format (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 re-saving leads to new losses (dropping) of data and transformation original image into porridge.

GIF (GraphicsInterchangeFormat). Independent of hardware The 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. In addition, a GIF file can 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 particularly evident in connection with the expanded use of 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, since 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 by Microsoft Internet Explorer starting with version 4 for 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 important format features such as seamless 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 the PostScript language is universal, the file can simultaneously store vector and raster graphics, fonts, clipping paths (masks), equipment calibration parameters, and 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 the Acrobat Reader, Acrobat Exchange applications.

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

The Encapsulated PostScript format can be called the most reliable and universal way to save 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 Mac, save thumbnails in JPEG format; other Mac programs save thumbnails 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 a function Save As. 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, in order to do this, in most cases you will need the full Adobe Acrobat package containing 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 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.

CDR (CorelDRAW Document). The CDR file format is a vector image or drawing created using CorelDRAW. This format file 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 compatibility files, however, using CorelDRAW is extremely convenient. 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, the AI format is adapted to store traditional graphics data: drawings, drawings and decorative inscriptions. 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 original file small. Raster file formats store information quite efficiently, as compression methods are often used. Vector formats do not have this ability. Therefore, the raster object stored in vector file, can be significantly larger 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 fact is that raster images that 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

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.

Knowledge of file formats and their capabilities is one of the key factors in pre-press preparation of publications, preparation of images for the web and in computer graphics in general.

Yes, today there is no such kaleidoscope of extensions as in the early 90s, when every image editor 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, but compress with JPEG".

Each of the formats established today has undergone natural selection and has proven its viability and necessity. They all have some characteristics and capabilities that make them indispensable in their work.

Knowledge of the features and subtleties of technology is important for modern designer just as for an artist it is necessary to understand the differences in the chemical composition of paints, the properties of soils, types of metals and types of wood.

The main purpose of Knowledge, by and large, is to expand a person’s capabilities, to increase the degree of his freedom, when a person acts as he sees fit, and not as his circumstances force him to do.

Formats:

GIF | JPEG | PNG | TIFF | PostScript | EPS | PDF | Scitex CT | Adobe Photoshop Document | Adobe Illustrator Document | Macromedia FreeHand Document | CorelDRAW Document | PICT |WMF | BMP | RTF

Compression methods:

LZW | JPEG | Huffman | CCITT | RLE (Run Length)

All graphic data in a computer can be divided into two large branches: raster and vector. Vectors are a mathematical description of objects relative to the origin. Simply put, for the computer to draw a straight line, the coordinates of two points are needed, which are connected along the shortest path, the radius is specified for the arc, etc.

Thus, a vector illustration is a set of geometric primitives. Most vector formats can also contain raster objects embedded in the file or a link to a raster file (OPI technology).

The difficulty when transferring data from one vector format to another lies in the use of programs various algorithms, various mathematics when constructing vector and describing raster objects.

OPI (Open Prepress Interface) is a technology developed by Aldus that allows you to import not original files, but their images, creating in the program only a low-resolution copy (sketch) and a link to the original. During the printing process, the sketches are replaced with the original files. Using OPI, instead of simple embedding, makes it possible to save computer resources (primarily memory), significantly increasing its performance. OPI is the primary tool for working with imported graphics files in programs such as FreeHand and QuarkXPress, and is widely used in other products.

A raster file is simpler (to understand, at least). It is a rectangular matrix (bitmap), divided into small squares - pixels (pixel - picture element). Raster files can be divided into two types: intended for display and for printing.

The resolution of files in such formats as GIF, JPEG, BMP depends on the computer's video system. In old Macs, there were 72 pixels per square inch of screen (screen resolution); on Windows, there was no single standard, but today the most commonly used value is 96 pixels per square inch of screen. In reality, however, these parameters have now become quite arbitrary, since almost all video systems of modern computers allow you to change the number of pixels displayed on the screen.

Raster formats intended exclusively for display have screen resolution only, meaning one pixel in the file corresponds to one screen pixel. They are also printed in screen resolution.

Raster files intended for pre-press preparation of publications have, like most vector formats, the Print Size parameter - the printed size. Associated with it is the concept of print resolution, which is the ratio of the number of pixels per square inch of a page (ppi, pixels per inch or dpi - dots per inch - the term is not entirely correct, but is often used).

Print resolution can be from 130 dpi (for a newspaper) to 300 (high-quality printing), almost never needed anymore.

Raster formats also differ from each other in their ability to carry Additional information: various color models, vectors, Alpha channels or spot color channels, layers various types, leading (interlaced loading), animation, compression capabilities and more.

GIF (CompuServe Graphics Interchange Format)

The 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.

The LZW (Lempel-Ziv-Welch) compression method was developed in 1978 by the Israelis 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 an image contains sets of pink, orange and green pixels repeating 50 times, LZW detects this, assigns this set single number (for example, 7) and then stores this data 50 times as the number 7. The LZW method, like RLE, performs better in areas of uniform, noise-free colors, and it performs much better than RLE at compression arbitrary graphics data, but the encoding and decompression process is slower.

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. In addition, a GIF file can 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 main limitation of the GIF format is that a color image can only be recorded in 256 colors or less.

JPEG (Joint Photographic Experts Group)

Strictly speaking, JPEG is not a format, but 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 graphics 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.

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 CMYK JPEG causes problems in many programs. The best solution is to use JPEG compression in Photoshop EPS files, which is described below.

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 and more data losses (discarding) and turning the original image into a mess.

The LAB color space represents color in three channels: one channel dedicated to luminance values (L - Lightnes) and the other two for color information (A and B). Color channels correspond to a scale, not to any one color. Channel A represents a continuous spectrum from green to red, while channel B represents a continuous spectrum from blue to yellow. The average values for A and B correspond to real shades of gray.

There is a similar YCC color model used in Kodak Photo CD and FlashPix formats not covered here.

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.

PNG (Portable Network Graphics)

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 usually smaller than similar GIF files, and PNG RGB is smaller than the corresponding TIFF file.

PNG files can have any color depth, 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 transparency is like honey - either it is there or not, PNG also supports translucent pixels 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 the picture created on Mac looks the same on Windows and on various UNIXes. 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 important format features such as seamless transparency and gamma correction has not yet been implemented.

TIFF (Tagged Image File Format)

The hardware-independent TIFF format appeared as an internal format of the Aldus PhotoStyler program. Its modular architecture turned out to be so successful that, having successfully survived the death of its native program, TIFF continues to improve and develop today.

Today it is one of the most widespread and reliable; it is supported by almost all programs on PC and Macintosh in one way or another related to graphics. Generally, 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 solid colors. TIFF may contain clipping paths, alpha channels, layers, and other additional data.

The exception, to some extent, is FreeHand. Sometimes TIFF files in it can randomly change their location when creating a PostScript file or directly in the document when opening it. More often than not, TIFFs “jump” while in the clipping path. With FreeHand, it is still preferable to use EPS.

TIFF can be saved in two recording orders: 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.

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

Adobe PostScript

PostScript - page description language (control language laser printers) from Adobe. It was created in the 80s to implement the WYSIWYG (What You See is What You Get) principle. Files of this format are a program with execution commands for an output device. They have the extension .ps or, less commonly, .prn and are obtained using Print functions to File graphics programs when using a PostScript printer driver.

Such files contain the document itself (only what was located on the pages), all associated files (both raster and vector), the fonts used, as well as other information: color separation boards, additional boards, screen lineature and shape raster dot for each board and other data for the output device. If the file is created correctly, it does not matter what platform it was made on, whether True Type or Adobe Type 1 fonts were used - it makes no difference.

However, you need to take into account that even if you have made the correct settings in the print window, problems may arise due to the incorrect translation of the graphic language program you are using into the PostScript language (for example, the introduction of information about unused fonts). The most correct PS files are created by Adobe programs.

Data in a PostScript file is usually written in binary encoding. Binary code takes up half the space of ASCII. ASCII encoding is sometimes required for transferring files over networks, for cross-platform sharing, and for printing over serial cables. In the above cases binary encoding may become corrupted (making the file unreadable) or cause "strange" behavior on the file server. These problems have long been eliminated in modern systems, but old computers and servers are susceptible to them.

The above applies to all PostScript-based formats: EPS and PDF, which are described below.

A more detailed description of the PostScript language, its features, problems and methods of printing from various programs you can find it on my website in the article “Non-scary PostScript”.

EPS (Encapsulated PostScript)

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.

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). CorelDRAW also offers the vector format WMF for sketches, you should use this Microsoft brainchild very carefully - it will not lead to any good.

Initially, EPS was developed as a vector format, later its raster version appeared - Photoshop EPS. In addition to the thumbnail type (TIFF, PICT, JPEG), Photoshop allows you to choose the data encoding method. ASCII, Binary and JPEG. The first two were described above; JPEG is worth focusing on.

Photoshop allows you to compress raster data using the JPEG algorithm. Adobe has improved this compression method. Photoshop's JPEG now supports CMYK and compresses better than JPEG that fully complies with the original specifications. In other words, JPEG-encoded non-thumbnail EPS files weigh less than comparable JPEG files! However, I would like to draw your attention to an important feature when working with JPEG compression in EPS.

Printer and phototypesetting drivers cannot perform color separations on such files. That is, when performing color separation on your computer, the JPEG-compressed EPS image will appear entirely on the first board (Cyan, usually). However, in the service bureau, Scitex workstations (the majority of them in Israel) can color separate pages with JPEG EPS illustrations without any problems. I think systems from other companies also support JPEG EPS, in any case it’s worth asking. In service bureaus and printing houses in Tel Aviv, I was often recommended to use JPEG EPS instead of TIFF for recording raster data, since it is faster to output.

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, 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 also make sense to be converted 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 (Portable Document Format)

PDF is proposed by Adobe as a platform-independent format for creating electronic documentation, presentations, and transferring layouts and graphics over networks. Used as an internal graphics format in Mac OS X.

PDF files are created by converting from PostScript files or using the export function of a number of programs. Adobe Acrobat Distiller is used for conversion; this is the best way to create PDF. Creating PDFs using the export method from programs usually gives worse results - the files are heavier and often have problems with embedding fonts.

To create PDF, there is also a PDFWriter program that works as a virtual printer. PDFWriter is not PostScript based and cannot handle graphics correctly. It is designed for quickly producing simple text documents. It has the same problem with embedding fonts as many programs that can export PDF. The most reliable and closest to the original PDF is created from PostScript and EPS files by the Acrobat Distiller program, supplied in the Adobe Acrobat package.

PDF was originally designed as a compact electronic documentation format. Therefore, all data in it can be compressed, and different types of compression are applied to different types of information, the most suitable for them: JPEG, RLE, CCITT, ZIP (similar to LZW and also known as Deflate). Acrobat program Exchange 3 (which in version 4 became simply called Acrobat 4.0) allows you to create hyperlinks, fill in fields, include video and sound in a PDF file, and other actions.

The CCITT (International Telegraph and Telephone Committie) compression method was developed 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.

The PDF file can be optimized. Repeating elements are removed from it, a page-by-page order is established for loading pages via the web, with priority first for text, then graphics, and finally fonts. However, when there are no duplicate elements, the file, after optimization, usually increases slightly.

PDF is increasingly being used to transmit graphics and layout over networks in a compact form. It can retain all the output device information that was in the original PostScript file. This concerns PDF versions 1.2 (Acrobat 3) and higher. However, version 1.2 cannot include trapping information, some other specific data (DSC, for example), and does not use color profiles. All this is implemented in subsequent versions of the format.

You can find a more detailed description of technologies based on Adobe Acrobat PDF on my website in the article Man-Orchestra 3.0.

Scitex CT

A PostScript file intended for output goes through a number of stages on its way to the phototypesetting machine. The most important of these is rasterization - the process of converting PostScript data into a bitmap, performed by the PostScript interpreter (RIP).

CorelDRAW format files can be used to transfer/transfer works to a PC, but it is not advisable to import them into layout programs. On a Macintosh, CorelDRAW for Windows files open with the Macintosh version of CorelDRAW and Adobe Illustrator 8 or later.

PICT (Macintosh QuickDraw Picture Format)

PICT is a native Mac OS Classic format. Standard for the clipboard, uses the Mac OS graphical language. PICT is capable of carrying raster, vector information, text and sound, and uses RLE compression. Supported on Mac by all programs. Pure bitmap PICT files can have any bit depth (from Lineart to CMYK).

Vector PICT files, which have all but disappeared from use these days, had strange problems with line thickness and other printing variations.

The format is used for the needs of Mac OS, and when creating certain types of presentations only for Macintosh. Outside the Macintosh PICT has the extension .pic or .pct, read separate programs, but working with it is rarely simple and unsophisticated.

WMF (Windows Metafile)

The vector format WMF uses graphic Windows language and, one might say, is its native format. Used to transfer vectors via the clipboard. Understood by almost all Windows programs that are somehow related to vector graphics.

However, despite its apparent simplicity and versatility, the WMF format should be used only as a last resort for transmitting bare vectors. WMF distorts color, cannot save a number of parameters that can be assigned to objects in various vector editors, cannot contain raster objects, and is not understood by many Macintosh programs.

BMP (Windows Device Independent Bitmap)

Another dear Windows format. It is supported by all graphic editors running this operating system. It is used to store bitmap images intended for use in Windows and, in fact, is not suitable for anything else.

Capable of storing both indexed (up to 256 colors) and RGB colors (more than 16 million shades). It is possible to use compression based on the RLE principle, but this is not recommended, since many programs do not understand such files (they may have the .rle extension). There is a version of the BMP format for the OS/2 operating system.

Using BMP for purposes other than Windows is a common mistake for newbies. It is important to understand that it is not advisable to use BMP either on the web, or for printing (especially), or for simple transfer and information storage.

RTF (Microsoft Rich Text Format)

The RTF text format came here for its extraordinary ability to transfer texts from one program to another. It allows you to transfer formatted text from optical character recognition programs or text editors to graphics programs or in any other direction. RTF may be good decision(and, sometimes, the only way out) when transferring non-Latin, for example, Hebrew text or Russian in Windows 95/98 Hebrew Edition from program to program.

The secret to compatibility is the use of special RTF and Unicode formatting tags. It is Unicode (used as the basis of the format Microsoft Word 97/98 for Macintosh and PC) allows you to easily transfer Russian texts from PC to Mac and back in MS Word 97/98 files (true for higher versions of Word).

RTF is used as the main one in the TextEdit editor supplied with Mac OS X and in the accompanying Windows program WordPad.

The abundance of images used on computers can be divided into three large groups. First of all, 2D graphics, in which flat (without a third coordinate) images are created; this group includes raster and vector graphics. Then 3D graphics and motion graphics.

Since images are created using special tools - graphic editors - it is impossible to consider file formats without taking into account their features. First of all, what is a graphics file? In the most general case, this is the system of image information adopted in a given graphics editor and the method of saving (recording) it. Such an information system can contain both general data (representation of an image on a particular display device, size, resolution, type of printer for printing, degree and method of information compression), and data that is specific and unique. Such data is created during the image editing stage and is intended for subsequent use during editing. For example, CorelDraw files contain information about curves, Photoshop files- information about layers, channels, etc. Each graphic editor encodes this information in a certain way when recording (saving) on a medium. Thus, the graphic file format should be understood as a set of information about the image and the method of recording it in the file. In general, everything graphic formats can be divided into two groups. Formats general purpose contain only the image itself and are intended for storing, transferring or viewing images (gif, tiff, jpeg, etc.) and specific formats intended for storing intermediate results of image editing (cdr, cpt, psd, ai, etc.).

Let us dwell in more detail on the 2D group due to its greatest prevalence. A raster graphics image is an ordered array of unit elements (pixels for a monitor or dots for a printer) containing color information. The number of such elements is determined by the image size and resolution, and the file size additionally depends on the color palette used (black and white or 1-bit, grayscale and 256 colors or 8-bit, high color or 16-bit, true color or 24-bit ). Vector graphics contain mathematical descriptions of the curves and fills (areas filled with a single color and areas of gradients) that make up an image. The issue of resolution and color palette is decided immediately before the file is output to a specific physical device and taking into account its characteristics. In the printing industry, this process is known as RIP - rasterizing an image process.

File compression. Since graphic files tend to be large, the ability to compress (pack) information is useful. There are currently two known compression methods - lossless and lossy. Lossless compression algorithms are similar to those of conventional archivers (LZH, PKZIP, ARJ). The most famous of them, LZW (LZ84), is widely used in the popular raster formats GIF and TIFF. Lossy compression algorithms discard information that is not perceptible to humans (JPEG, PCD). The degree of compression in this case is much higher, but occurs more slowly and can lead to deterioration in quality (depending on the selected compression ratio). The main disadvantage of this algorithm is the impossibility of recompression without significant loss of the original image quality. Therefore, it is recommended to save only the final editing results in JPEG format, and in no case intermediate ones.

General purpose formats

Microsoft Windows Bitmap (BMP)

A format for storing raster graphics in a Microsoft Windows environment (for example, screen wallpapers and screensavers). Supports 1-, 4-, 8-, 24-bit color. Allows compression without loss of quality.

Kodak Photo CD (PCD).

The developer is Kodak. The format is intended for storing slides and negatives captured using a Kodak Photo CD type camera. Each file stores 5 copies of one image of different sizes and qualities from 192x192 to 3072x2048 pixels. It is impossible to programmatically record a PCD image on a computer; you can only import the image into a graphics editor that supports this format.

Zsoft PC PaintBrush (PCX)

One of the oldest and most famous formats for storing raster graphics. It appeared almost along with personal computers, due to which it is the most common and is supported by almost all image viewing/editing programs. Uses the simplest lossless compression algorithm RLE.

Tag Image File Format (TIFF)

Developers: Aldus and Microsoft. A universal format for storing raster graphics, widely used in publishing. It is necessary to make a reservation that there are quite a lot of its varieties, due to different compression algorithms. The format that uses the LZW algorithm has the greatest compatibility. The format supports 24 and 32-bit color (CMYK), two types of recording IBM PC and Macintosh, and can store information about masks (selected areas of the image).

TrueVision TGA (TGA)

Developed by TrueVision. The format is used for storing raster graphics and has an interesting feature - along with support for 24-bit color, it has another 8 bits for each single image element to store additional information. In particular, it may contain a mask, which is used in video editing programs, for example, to create an overlay of two sequences of frames. It has been known for a long time and is supported by many graphics packages.

Graphics Interchange Format (GIF)

Developed by CompuServe Corporation in 1987 for storing raster graphics. Implemented one of the most effective LZW compression methods for its time (87g). Allows you to display an image on the screen in four passes, allowing you to preview the image before its final drawing. In 1989, a new version of GIF 89a appeared. This format supports saving multiple images, animation sequences, and transparency colors in one file for the purpose of overlaying images on top of each other. Still widely used to store and transmit small images (page design elements) to the World Wide Web.

Joint Photographic Experts Group (JPEG)

The raster format owes its popularity to the high degree of compression of the source image, based on a lossy compression algorithm. However, this applies primarily to 24- and 8-bit images. There are several varieties, due to different compression algorithms and display methods (gradual rendering is similar to gif). Also widely used on the WWW, mainly for transmitting large images.

Specific formats

As mentioned above, this group of formats is intended mainly for “internal” use (storing intermediate results of image editing). In addition to information about the image itself, the files contain a lot of service data that cannot be correctly interpreted by other viewing/editing programs. Such data may include information about fonts, layers, selections (masks), curves, special effects, etc. The most common formats are for vector graphics - cdr (Corel Draw) and ai (Adobe Illustrator), for raster graphics - psd (Adobe Photoshop ) and cpt (Corel PhotoPaint). Typically, the final image (ie the image intended for publication) is imported into one of the general purpose formats depending on the purpose of publication (gif or jpeg for the Internet, tiff for publishing systems, etc.).

Igor Sivakov