Raster graphics files usually have. Basic graphic file formats
The GIF format was developed in 1987 by computer information service CompuServe. Advantages
- Small size, which can be achieved with limited color scheme- no more than 256 colors.
- Transparent background.
- Animation.
The fruit of the community of independent programmers - a response to the transition of the most popular GIF format into the category commercial products. PNG format does almost everything the GIF format does except animation. Advantages
- The best data compression - compresses raster images not only horizontally, but also vertically.
- Supports color photographic images up to and including 48-bit.
- 256 levels of transparency.
A format similar to PNG-8, but using a 24-bit color palette.
This allows you to save photographs and complex drawings in this format. Advantages
- Full color palette.
- High-quality transparency allows you to overlay the design on any background
For search the best way compression of photographic quality images, two standards organizations - the International Telecommunications Union (ITU) and the International Organization for Standardization (ISO) - created the Joint Photographic Experts Group (JPEG).
Uses lossy compression. With this compression, information that is not essential for the perception of the image is removed. WBMP(WAP BitMap)
monochrome (two-color) images.
The maximum image size should not exceed the card size limit - 1.5 KB. BMP(BitMap)
The simplest raster format, BMP, is a native Windows format. BMP stores color data only in the RGB model, meaning it is a format designed for use on screen. PCX(PCExchange)
Images in PCX format can be viewed with most DOS programs. Like BMR, this format is largely outdated and is supported by modern graphics programs solely for compatibility with antique software. TIFF, TIF(Tagged Image File Format)
Originally developed by Aldus for its PhotoStyler graphics editor. As a universal format for storing raster images, TIFF is widely used, primarily in publishing systems that require the best quality images. Due to its compatibility with most professional image processing software, the TIFF format is very convenient when transferring images between different types of computers (for example, from PC to Mac and vice versa). PSD(Photoshop)
The Adobe Photoshop format is distinguished by the ability to store layers. Convenient only for processing in Photoshop and for storing the source for editing in the future. RAW(RAW Image Data)
The format is designed for digital cameras. This is an exact copy of the image captured on the matrix during shooting; it consists of three photographs taken in red, blue and green colors.
RAW file extensions different manufacturers may differ, and it is not always possible to open them using image processing programs.
Although if a camera supports saving RAW, then, as a rule, it comes with some kind of program for processing files of this format.
Currently, Adobe has proposed the DNG (Digital Negative Specification) format, which was created in order to make life easier for manufacturers of graphics tools. Some companies (Leica and Pentax) have already included DNG in their cameras, but most camera vendors still continue to use their formats.
RAW format extensions
.dng - Adobe (generic)
.crw .cr2 - Canon
.raf - Fuji
.kdc - Kodak
.mrw - Minolta
.nef - Nikon
.orf - Olympus
.ptx .pef - Pentax
.x3f - Sigma
.arw - Sony
Vector graphics
CDR(CorelDRAW)The format of the popular CorelDRAW, which is the undisputed leader in the class of vector graphics editors on the PC platform. Having relatively low stability and problems with compatibility of files of different versions of the format. A.I.(Adobe Illustrator)
Being part of the Adobe family, they support almost all programs related to vector graphics in one way or another. The best intermediary for transferring images from one program to another, from PC to Macintosh and vice versa. It is characterized by the greatest stability and compatibility with the PostScript language, which is used by almost all publishing and printing applications. WMF(Windows Metafile)
Another native Windows format, this time vector. Understood by almost everyone Windows programs, one way or another related to vector graphics. EMF(Enhanced Metafile)
Similar to WMF.
OTHER FORMATS
SWF(ShokWaveFlash)Flash format, a product of Macromedia, which allows the development of interactive multimedia applications. The scope of Flash use is different, it can be games, websites, CD presentations, banners and just cartoons. When creating a product, you can use media, sound and graphic files, you can create interactive interfaces and full-fledged web applications with using PHP and XML.
SVG(Scalable Vector Graphics) Standard Recommended World Wide Web Consortium for describing using XML markup two-dimensional vector and combined vector- raster graphics.
In the browser, SVG graphics are rendered using raster engines. Support for translucency in each layer, linear gradients, radial gradients, visual effects(shadows, washes, shiny surfaces, textures, patterns of any design, symbols of any complexity).
SVG is a format for 2D vector graphics as defined in the specification, but by adding script (namely JavaScript) inside an SVG file you can create 3D animated images.
SVG can have a built-in raster image, which, like any other object in SVG, can have transformation, transparency, etc. applied to it. ICO(Icon)
Icons are used in all kinds of programs on a computer and smartphone. But the average person may generally need to create or use an icon on their website.
Many people are trying to start their own website. Even if you use a ready-made website template with a style that only needs to be filled in, it would still be nice for you to make a unique icon. An icon on the Internet is used as a symbol of a site, a logo. For example, now you see a red square in the address bar. If you add a page of our website to your favorites, our icon will appear next to the link, which will help you quickly visually find the link to the site. Actually, this is the main purpose of an icon on the Internet.
PostScript
EPS(Encapsulated PostScript)The most reliable and in a universal way saving data. It uses a simplified version of PostScript, 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.
WHICH FORMAT SHOULD I CHOOSE?
| For the Internet | |
| photograph or drawing with flowing tones | JPEG |
| picture with straight lines, small range of colors with a smooth fill (no gradient) |
GIF PNG |
| complex picture with transparent background | PNG-24 |
| animation | SWF |
| icons | ICO |
| For printing and storage | |
| For print | TIFF |
| For storage | PSD |
| For logo | EPS (CDR AI) |
| Logo for MS Office | WMF |
| For photography | |
| For storing and printing photos, but not of low quality | JPEG |
| For printing and for the original of the best quality | RAW |
The variety of formats used to record images can be divided into three categories:
Formats that store images in raster form;
Formats that store images in vector form;
Universal formats that combine vector and raster representation.
Raster formats
The BMP (BitMap) raster format is designed for use in the Windows operating system. It is used to represent bitmap images in program resources. Supported by all graphic editors running operating system Windows. The format works with images whose color depth ranges from 1 to 24 bits. Provides the ability to compress data using the RLE method (not recommended due to compatibility issues).
The BMP format is not suitable for printing or web design; it is recommended to be used only for Windows needs (creating icons, desktop backgrounds, etc.).
PCX (PC eXchange) is one of the oldest graphic formats, created for the PC Paintbrush program, the files of which open in almost all graphic editors. Supports monochrome, grayscale, indexed and full color images in the RGB model. Assumes the use of RLE compression. It has a large number of versions, but is currently being actively replaced by other formats.
TIFF (Tagged Image File Format, TIF) is designed as a universal format for storing scanned images. Supports almost all types of images: monochrome, grayscale, indexed and full-color images in RGB and CMYK models with eight- and sixteen-bit channels.
Currently, its scope has expanded significantly; it is one of the most common and reliable graphic formats, versions of which exist for PC and Macintosh. It is supported by almost all major raster and vector graphics packages, publishing systems, as well as text editing and layout programs.
Unlike the formats discussed above, TIF supports a number of additional functions(almost all elements of the structure of Photoshop documents): saves the multi-layer structure of the document, information about the degree of transparency of pixels, descriptions of clipping paths, mask channels (alpha channels), etc. Provides the ability to compress data using the LZW algorithm. Today TIF is best choice when exporting raster graphics to vector programs and publishing systems.
The GIF (Graphics Interchange Format) format was created specifically for transferring raster images into global networks. It is compact-oriented, uses the LZW compression algorithm, and interlaces the transmission of graphic data. This allows you to very quickly see a rough version of the image before the file is fully downloaded. The format is used only for its original purpose - on the Internet, since it only supports indexed images.
GIF allows you to save several indexed images in one file, the sequential display of which (by browsers) is a simple animation. The animation file stores not only the frames themselves, but also the parameters for its demonstration. GIF animation is very common on the Internet. In addition, a certain color in the indexed palette can be designated as “transparent” and then the background of the page will be visible in the browser through areas of this color.
The GIF format is very popular. It is supported by almost all raster graphics editors and editors that create images for the web.
The JPEG (Joint Photographic Experts Group) format gets its name from the corresponding compression method. Today, JPEG is one of the most common graphic formats for file compression. Unpacking of data contained in files of this format occurs automatically when the file is opened.
JPEG does not support monochrome (single-bit), indexed, or multi-channel images. It does not have the ability to store layers, masks, or transparency information. When saving a multilayer image in JPEG format, all layers are first combined into one and information about the original layers is lost. In addition, if there were transparent areas in the original image, they will be assigned White color, transparency information will be lost.
JPEG is most widely used in creating images for electronic distribution on CD or online. Not recommended for use in printing. This format should only be used for photographic images. Drawings with sharp edges and large filled areas show strong compression defects. This results in "dirt" appearing around dark lines on a light background and visible square areas. Even when working exclusively with photographic images, it is better to use JPEG only to save the final version of the work, because each intermediate save leads to new data losses (discards).
The PCD (Photo CD) format is used in publishing systems as a format for image sources. Most photo library manufacturers use this format on their CDs. PCD has a number of features that determine its use specifically in the field of creating photo collections.
A PCD file contains an image in several fixed resolutions at once. Base resolution 512x768 pixels is used for viewing on NTSC and PAL TVs. In addition, there are lower resolutions Base/4, Base/16 and higher resolutions 4Base, 16Base, 64Base (on Pro Master standard discs). When opening an image in PCD format, you can select any of the given resolutions, which avoids lengthy loading and subsequent scaling.
The images on the Photo CD are presented in a special YCC color model, much like Lab. The YCC model is useful for compressing information, but is not supported by most applications. When you open files in this format, graphics programs immediately convert the YCC color model to grayscale, RGB or Lab. Popular graphic editors are not able to save images in PCD format, but can only open them.
PSD (PhotoShop Document) is a proprietary format of Adobe Photoshop. The only format that supports all the features of this program. It is preferable for storing intermediate results of image editing (if the editing was done in Photoshop), as it completely preserves their structure (layers, channels, masks, texts, transparency and much more). The PSD format can store images of any type: monochrome, grayscale, indexed, full color, multi-channel. As the program became more popular and widespread, the format acquired some versatility and can now be easily opened by most applications. The disadvantages of the format include the lack of compression capabilities.
The PNG (Portable Network Graphics) format, like GIF, is designed for transmitting images over the network.
The format supports grayscale and full-color RGB images with a single alpha channel, as well as monochrome and indexed
bathroom images without alpha channels. The alpha channel serves as a transparency mask. Thus, PNG is the only format common on the Internet that allows you to obtain full-color images with a transparent background. In addition, to speed up the appearance of the image on the screen, PNG uses a two-dimensional interlaced output mode (not only rows, but also columns). PNG uses a lossless compression algorithm based on LZW compression.
FLM (Filmstrip) is Adobe Premier's own format, a video editing and presentation program. Photoshop allows you to open and edit footage created in Adobe Premier.
Depending on how well you understand graphic formats, the final result of all the work will directly depend. Understanding what format to save images and photos in is extremely important. Most likely, you have often thought and asked yourself in what format is it better to save images and photographs. In this tutorial we will look at main formats graphic files which photographers most often use, we’ll talk about the pros and cons of each of them and give valuable recommendations. Let's start!
JPEG (or JPG) (Joint Photographic Expert Group)
Let's start the review with the most popular and generally accepted format today - JPEG or JPG. When you save an image in this format, some digital data is lost. This happens because JPG uses a specific compression algorithm. Why do people use it then? The answer is simple: because the JPG format preserves the colors that the human eye sees, while the file size is significantly smaller than others. Although a JPEG image is great for viewing on devices and on the Internet, remember that you should not save images in JPEG that are subject to further processing, as the quality will deteriorate with each new save. Today it is the most common graphic format.
BMP (Bitmap Picture)
The simplest BMP format was used in the first versions of Windows. In BMP, color data is stored in the RGB model and it can store both indexed colors (256 colors) and full-color images, and in the first case, the simplest RLE (Run Length Encoding) compression is possible. Without compression, the file size is close to the maximum possible. Today it is used for images intended for use in Windows. By the way, using BMP not for Windows needs is a common mistake of all beginners. Remember to use BMP neither for the web, nor for printing, nor for simple transfer and information storage.
TIFF (Tagged Image File)
TIFF was originally developed by the talented company Aldus for its PhotoStyler graphics editor. This format is very popular among photographers, but for a completely different reason than JPG. TIFF files can be saved by two different ways: Either with little compression or no compression at all. In addition to photography, it is widely used in publishing systems that require the best quality images. A TIFF file stores complete information about each pixel of the photograph taken. TIFF files are used on both Macintosh and Windows platforms, and weigh many times more than JPG because they do not use compression.
GIF (Graphics Interchange Format)
This format was created by CompuServe back in 1987 and is even used on the Internet today along with JPG. Online The GIF format has some advantages over JPG. If you save the image as a GIF with 256 colors, the file size will be amazingly small and very different from the original. On the other hand, this is not best technology to use this format in digital photography. It is best to save an image as a GIF if the image contains some text (for example, a logo, or a black and white image).
RAW (raw file)
Favorite format of a professional photographer. When using this format, the image data is left unprocessed, resulting in images with a lot of information, which significantly impacts the file size. In a program (For example, Photoshop or LightRoom), a photographer can easily edit image parameters such as exposure time, filters, modes and many other parameters.
Which format to use
It depends on how you intend to use the images. Below are some recommendations that should help you.
JPG
Most digital cameras save images as JPG by default. As mentioned above, JPG is a pretty good compromise between image quality and file size. But you may not know that you can control the degree of compression of JPG images in your camera, and therefore their quality. Take a closer look at the camera settings; no doubt, you will find somewhere a means of adjusting the image quality. It can be located in the menu system or be a button on the camera body.
Note that the concept of image quality is quite different from the concept of resolution. Permission - is the number of pixels that make up the image, and image quality is determined by the amount of color information that can be stored in each pixel, and this parameter can be used to determine what percentage of image quality is sacrificed.
Most cameras have several image quality settings, such as high, medium and low. I recommend that you choose the most high quality images for JPG format, since if you set the quality to low you will get completely unacceptable images. On the other hand, setting the highest image quality and resolution will use more.
Lossless graphics files
Many digital cameras can save files in another format - TIF. Remember that the TIF format, unlike JPG, is used when you need to ensure that the image is saved without losing data.
It is best to use the TIF format if the photograph is being used specifically so that it can later be cropped, enlarged and printed. Indeed, for professional work, the TIF graphic format may be necessary, but even in such cases, the high resolution and quality of the JPG format may be sufficient. Remember, however, that the accuracy provided by the TIF format seriously affects the amount of memory required to store a single image. If you want to save a lot of pictures in TIF format, you should have the largest memory card you can afford.
In general, I suggest that you forget about TIF for a digital camera. It's not worth any sacrifice, since JPG with the image quality and resolution set to maximum is more than enough in 99.9% of cases. In addition, it takes a long time to write a TIF file to a memory card.
RAW
There is another file format that you may encounter in some digital cameras. RAW format is much better than TIF. As noted above, it stores completely uncompressed photo data.
A RAW file is like a digital negative - completely raw, unfiltered and untouched. Some professional photographers use RAW files because they give more creative options when processing an image. But not all digital cameras allow you to save photos in RAW.
Many graphics editors are not capable of processing RAW files. In order to open such a RAW file, you need to install a special application on your computer, a plug-in for a graphics editor. However, companies supply cameras with special software that understands RAW.
Digital images have a wide range of uses, which is why there are so many file formats. Below are some tips for choosing a file format that you might find useful:
- If you want to post an image online, then JPG is the best choice. But GIF files are good because they are convenient to place in text, due to the transparent background.
- If you are going to print large photos, such as 20x30 cm or more, then the most suitable formats are TIF and JPG.
- For slideshows and most similar projects, JPG is ideal.
- For professional work and flexibility in photography settings, use RAW
Lecture No. 3. Graphic file formats
Graphic file formats. BMP, TIFF, JPEG, GIF, PNG and other formats. Characteristics and Application 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 operating systems. Windows systems and OS/2. BMP files can have extensions .bmp, .dib and .rle. Additionally, data in this format is included in binary RES resource files and PE files.
IN BMP format You can save images with color depths (the number of bits that describe one pixel in the image) of 1, 4, 8, and 24 bits, which correspond to a maximum number of usable colors of 2, 16, 256, and 16,777,216. The file can contain a palette that defines colors other than accepted in the system.
TIFF(Tagged Image File Format). The format is designed for storing high-quality raster images (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 (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). 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.
Format JPEG file 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). 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.
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 graphic elements, and, first of all, on the resolution and color depth of the 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 supported in Microsoft Internet Explorer since version 4 for Windows and since 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 capabilities
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 shows in general terms real picture, 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 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, in order to do this, in most cases it is necessary full package Adobe Acrobat, 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.
To view, you can use the official free Adobe Reader program, 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 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 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 a vector image to a raster image. 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, 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 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
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.
INTRODUCTION
A graphics format is a way of recording graphic information. Graphics file formats are designed to store images, such as photographs and drawings.
Knowledge of file formats and their capabilities is one of the key factors in computer graphics. Yes, today there is no such kaleidoscope of extensions as in the early 90s, when 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 JPEG". Each of the formats established today has undergone natural selection and has proven its viability. They all have some characteristic features and capabilities that make them indispensable in their work. Knowledge of the features and subtleties of technology is also important for a modern designer, As an artist, it is necessary to understand the differences in the chemical composition of paints, the properties of soils, types of metals and rocks.
These are raster graphics, vector graphics, three-dimensional and fractal graphics. They differ in the principles of image formation when displayed on a monitor screen or when printed on paper.
Raster graphics are used in the development of electronic (multimedia) and printed publications. Illustrations made using raster graphics are rarely created manually using computer programs. Most often, scanned illustrations prepared by the artist on paper or photographs are used for this purpose. Recently, digital photo and video cameras have found widespread use for inputting raster images into a computer. Accordingly, most graphic editors designed for working with raster illustrations are focused not so much on creating images, but on processing them. On the Internet, raster illustrations are used in cases where it is necessary to convey the full range of shades of a color image.
Software tools for working with vector graphics, on the contrary, are intended primarily for creating illustrations and, to a lesser extent, for processing them. Such tools are widely used in advertising agencies, design bureaus, editorial offices and publishing houses. Design work based on the use of fonts and simple geometric elements is much easier to solve using vector graphics. There are examples of highly artistic works created using vector graphics, but they are the exception rather than the rule, since the artistic preparation of illustrations using vector graphics is extremely complex.
Three-dimensional graphics are widely used in engineering programming, computer modeling of physical objects and processes, animation, cinematography and computer games.
Software tools for working with fractal graphics are designed to automatically generate images through mathematical calculations. Creating a fractal artistic composition is not about drawing or design, but about programming. Fractal graphics are rarely used to create printed or electronic documents, but they are often used in entertainment programs.
The purpose of this test will be an initial study of graphic files and their formats, information compression methods, as well as an analysis of the work done.
The objective of this test will be to determine whether a graphic format belongs to a specific subtype: vector, raster, complex.
Information compression methods
Almost all modern graphics file formats use some kind of information compression method, therefore, for a better understanding of further material, the beginning of this section contains a brief summary of these methods.
Information compression methods:
One of the simplest compression methods is the RLE (Run Length Encoding) method. The RLE method works by searching for identical pixels in the same row. If a line, say, has 3 white pixels, 21 black, then 14 white, then using RLE makes it possible not to remember each of them (38 pixels), but to write it as 3 white, 21 black and 14 white in the first line .
The LZW (Lempel-Ziv-Welch) compression method was developed in 1978 by Lempel and Ziv, and later refined in the USA. Compresses data by searching for identical sequences (called phrases) throughout the file. The identified sequences are stored in a table and are assigned shorter markers (keys). So, if there are patterns of pink, orange, and green pixels in an image that repeat 50 times, LZW detects this, assigns a separate number to that set (for example, 7), and then stores that data 50 times as the number 7. The LZW method also , like RLE, performs better in areas of uniform, noise-free colors, it performs much better than RLE at compressing arbitrary graphics data, but the encoding and decompressing process is slower.
The Huffman compression method was developed in 1952 and is used as a component in a number of other compression schemes, such as LZW, Deflation, JPEG. The Huffman method takes a set of symbols and analyzes them to determine the frequency of each symbol. The most frequently occurring characters are then represented in the smallest possible number of bits. For example, the letter "e" is most often found in English texts. Using Huffman encoding, you can represent "e" with just two bits (1 and 0), instead of the eight bits needed to represent the letter "e" in ASCII.
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.
Graphics file formats
Raster format
Raster images are formed in the process of scanning multi-color illustrations and photographs, as well as when using digital photo and video cameras. You can create a raster image directly on your computer using a raster graphics editor.
A raster image is created using dots of different colors (pixels) that form rows and columns. Each pixel can take on any color from a palette containing tens of thousands or even tens of millions of colors, so raster images provide highly accurate color and grayscale reproduction. The quality of a raster image increases with increasing spatial resolution (the number of pixels in the image horizontally and vertically) and the number of colors in the palette.
The disadvantage of raster images is their large information volume, since it is necessary to store the color code of each pixel.
Let's look directly at the extensions of the raster graphics format:
1) The BMP file format (short for BitMaP) is the native raster graphics format for Windows because it most closely matches the native Windows format in which that system stores its raster arrays. The filename extension most often used in BMP format is BMP, although some files have the extension RLE, which stands for run length encoding. The RLE extension of a file name usually indicates that the file's raster information has been compressed using one of two RLE compression methods that are valid for BMP format files.
In BMP files, the color information of each pixel is encoded into 1, 4, 8, 16, or 24 bits (bits/pixel). The number of bits per pixel, also called color depth, determines the maximum number of colors in an image. An image with a depth of 1 bit/pixel can have only two colors, and with a depth of 24 bit/pixel - more than 16 million different colors.
2) PCX became the first standard graphics file format for storing raster graphics files on IBM PCs. This format, used in the ZSoft Paintbrush program, was used in the early 80s. Microsoft acquired a license and then distributed it along with Microsoft products. The format was later converted into Windows Paintbrush and began to be distributed on Windows. Although the use of this popular format is declining, PCX files, easily recognized by their PCX extension, are still widely used today.
PCX files are divided into the following three parts: a PCX header, raster array data, and an optional color table. The 128-byte PCX header contains several fields, including the image size and the number of bits to encode color information for each pixel. The raster array information is compressed using simple method RLE compression; An optional color table at the end of the file contains 256 RGB color values that define the colors of the image. The PCX format was originally developed for CGA and EGA display adapters and has been modified for use in VGA and true color adapters. The color coding of each pixel in modern PCX images can be done at 1, 4, 8, or 24 bit depth.
3) If PCX is one of the easiest raster graphics formats to decode, then TIFF (Tagged Image File Format) is one of the most complex. TIFF files have the extension TIFF. Each file begins with an 8-byte Image File Header (IFH), the most important element of which, the Image File Directory (IFD), serves as a pointer to the data structure. An IFD is a table for identifying one or more variable length pieces of data called tags; tags store information about an image. The TIFF file format specification defines over 70 different types of tags. For example, one type of tag stores information about the width of the image in pixels, while another stores information about its height. The third type tag stores a color table (if necessary), and the fourth type tag contains the raster array data itself. An image encoded in a TIFF file is defined entirely by its tags, and the file format is easily extensible because additional tag types can be defined to add additional properties to the file.
So what makes TIFF so difficult? On the one hand, writing programs that distinguish between all types of tags is not an easy task. Most TIFF file readers implement only a subset of the tags, which is why a TIFF file created by one program sometimes cannot be read by another. Additionally, programs that create TIFF files can define their own tag types that are meaningful only to them. TIFF file readers can skip tags they don't understand, but there is always the danger that this will affect the appearance of the image.
Another complication is that a TIFF file may contain multiple images, each with its own IFD and set of tags. The raster array data in a TIFF file can be compressed using any of several methods, so in reliable program To read TIFF files there must be decompression tools RLE, LZW (LempelZivWelch) and several others. To make the situation even worse, the use of LZW unpacking programs must be in accordance with a license agreement with Unisys Corp. for the right to use the LZW algorithm and often for a fee. As a result, even the best TIFF readers often give up when faced with an LZW-compressed image.
Despite its complexity, the TIFF file format remains one of the best for transferring raster arrays from one platform to another due to its versatility, which allows almost any image to be encoded in binary form without losing its visual or any other attributes.
4) Most of the leading graphics professionals dealing with the LZW algorithm face similar legal problems when using the popular cross-platform raster graphics file format GIF (Graphics Interchange Format, pronounced "gif"), developed by CompuServe. GIF files are typically named using the GIF extension, and thousands of them are available from CompuServe.
The structure of a GIF file depends on the version of the GIF specification that the file conforms to. There are currently two versions in use, GIF87a and GIF89a. The first one is simpler. Regardless of the version number, a GIF file begins with a 13-byte header containing a signature that identifies the file as a GIF, the GIF version number, and other information. If the file stores only one image, following the header there is usually a general color table that defines the colors of the image. If several images are stored in a file (the GIF format, similar to TIFF, allows you to encode two or more images in one file), then instead of a general color table, each image is accompanied by a local color table.
5) The PNG (Portable Network Graphic, pronounced "ping") format was developed to replace GIF in order to bypass the legal barriers to the use of GIF files. PNG inherits many of the features of GIF and, in addition, it allows you to store true color images. More importantly, it compresses raster array information using a variant of the highly respected LZ77 compression algorithm (predecessor to LZW), which anyone can use for free.
6) The JPEG (Joint Photographic Experts Group, pronounced JPEG) file format was developed by C-Cube Microsystems as an efficient method for storing images with high color depth, such as those obtained by scanning photographs with numerous subtle sometimes subtle) shades of color. The biggest difference between the JPEG format and the other formats discussed here is that JPEG uses a lossy (rather than lossless) compression algorithm for information. The lossless compression algorithm preserves image information in such a way that the decompressed The image is exactly the same as the original. Lossy compression sacrifices some of the image information to achieve a higher compression ratio. The decompressed JPEG image rarely matches the original exactly, but very often the differences are so small that they are barely (if at all) possible. discover.
Vector format
In this subsection we will look at the most common extensions for vector graphics files.
1) Encapsulated PostScript (EPS) - an extension of the PostScript format, data in which is recorded in accordance with the DSC (English, Document Structuring Conventions) standard, but with a number of extensions that allow this format to be used as a graphic one.
The EPS format was created by Adobe based on the PostScript language and served as the basis for the creation of early versions of the Adobe Illustrator format.
In its minimal configuration, an EPS file has a so-called BoundingBox DSC comment - information describing the size of the image. This way, even if the application cannot rasterize the data contained in the file, it has access to the image dimensions and its preview.
QuarkXPress versions 4, 5 and 6 cannot rasterize data from an EPS file, so it uses only a preview in the layout - a small copy of the entire image, which is stored in the EPS file separately from the main data. Adobe InDesign versions CS-CS4 do not have such a limitation. The use of a reduced-quality copy of the image is intended to simplify the display of the image on the screen and, as a result, significantly speed up the work with layout. Preview can be recorded in TIFF or WMF format (PC only) or omitted altogether.
The format is used in professional printing and can contain raster images, vector images, and combinations thereof.
An image recorded in EPS format can be saved in different color spaces: Grayscale, RGB, CMYK, Lab, Multi-channel.
The data structure of an EPS raster file can be written using different methods: ASCII data (text data), Binary data (binary data) and JPEG with different compression rates.
2) WMF (Windows MetaFile) - a universal format of vector graphic files for Windows applications. Used to store a collection of Microsoft Clip Gallery graphics. The format was developed by Microsoft and is an integral part of Windows, as it preserves a sequence of hardware-independent GDI (Graphical Device Interface) functions that directly output an image to a given graphics device context (to the screen, to a printer, etc.). Very often, WMF is used implicitly to save an image of a program's output window and restore it later, as well as when transferring information via the clipboard. From MS Windows, writing and reading a file of this format is extremely simple and fast; in other operating systems, support for this format is useless. Some Macintosh programs understand it. On the Macintosh platform, the PICT format plays a similar role.
3) CDR file format - a vector image or drawing created using the CorelDRAW program. This file format was developed by Corel for use in its own software products. CDR files are not supported by many image editing programs. However, the file can be exported using CorelDRAW to other, more common and popular image formats.
Also, the CDR file can be opened with Corel Paint Shop Pro. For best compatibility, Corel recommends saving files in CorelDRAW CDR format version 9.0 or earlier.
4) Portable Document Format (PDF) is a cross-platform electronic document format created by Adobe Systems using a number of PostScript language features. Primarily intended for presentation in in electronic format printing products - a significant amount of modern professional printing equipment can process PDF directly. To view, you can use the official free Adobe Reader program, as well as third-party programs. The traditional way of creating PDF documents is a virtual printer, that is, the document as such is prepared in its own specialized program - a graphics program or text editor, CAD, etc., and then exported to PDF format for electronic distribution, transfer to a printing house and etc.
Complex format
There are also complex formats that can store both vector and raster information. This DjVu formats, CGM, AI (Adobe Illustrator program format), EPS (Encapsulated PostScript - a professional universal vector-raster format used by all professional graphics programs) and PDF (Portable Document Format - an Adobe Acrobat program format that can contain raster and vector graphics, and also text information).
1) DjVu (from the French déjà vu - “already seen”) - a lossy image compression technology designed specifically for storing scanned documents - books, magazines, manuscripts, etc., where the abundance of formulas, diagrams, drawings and handwritten symbols makes it extremely labor-intensive their full recognition. It is also an effective solution if it is necessary to convey all the nuances of design, for example, of historical documents, where not only the content is important, but also the color and texture of the paper; parchment defects: cracks, marks from folding; corrections, blots, fingerprints; traces left by other objects, etc.
DjVu has become the basis for several libraries of scientific books. A huge number of books in this format are available on file-sharing networks.
The format is optimized for network transmission so that the page can be viewed before the download is complete. A DjVu file can contain a text (OCR) layer, which allows full-text search of the file. In addition, a DjVu file can contain a built-in interactive table of contents and active areas - links, which allows for convenient navigation in DjVu books.
2) CGM (from the English Computer Graphics Metafile) - a format for storing and exchanging graphic data that is not related to CAD.
3 Dpolygons
The X file format is a file format for storing 3D objects created by Microsoft.
This format stores information about the geometry of a 3D object (vertex coordinates and normal coordinates), texture coordinates, description of materials, paths and names of textures that are used. The hierarchy of objects is stored, the animation is stored, and the bindings of vertices to “bones” with a description of the weights are stored. The X file may not contain any information about the object (for example, the X file may only contain vertex coordinates).
An X file can be text or binary.
At the beginning of the X file there is a header, then there is a description of information about the object. The description of information can be in any order, but the title always comes at the very beginning.
CONCLUSION
No other area of computer application can boast such a variety of file format types as computer graphics. Every more or less reputable software company considers it their duty to create at least some kind of graphic editor, and in addition to it, it goes without saying, they create their own file format in which, as the developers assure, this editor saves the masterpieces created with its help , the best way. As a result of this approach, a situation has arisen where no one is able to cover all the variety of types of existing graphic formats. Graphic files are quite complicated, unlike, say, a simple text file. Over time, the need arose to obtain graphic files with certain requirements. For example, a computer artist needs very high picture quality, while an ordinary user needs good quality, but not a very large volume, a web designer needs to get a more or less decent image with a minimum volume. But the requirements for file portability between different applications forced the identification of several specific formats, which have become, each in their own area, de facto standards. Thus, for images on the Internet, in most cases, JPEG and GIF formats are used, for storing images - JPEG, in publishing TIFF reigns, etc.
This is not to say that there are bad formats and there are good ones. Each format has advantages and disadvantages. This article will talk about only some of the graphic formats that are supported by most graphics programs and are used in practice more often than others.
Raster images are saved in a file in the form of a rectangular table, in each cell of which the binary color code of the corresponding pixel is written. Such a file stores data about other properties of the graphic image, as well as its compression algorithm.
Vector images are saved in a file as a list of objects and the values of their properties - coordinates, sizes, colors, etc.
There are quite a large number of both raster and vector graphic file formats. Among this variety of formats, there is no ideal one that would satisfy all possible requirements. The choice of one or another format for saving an image depends on the goals and objectives of working with the image. If photographic accuracy of color reproduction is needed, then preference is given to one of the raster formats. It is advisable to store logos, diagrams, and design elements in vector formats. The file format affects the amount of memory the file occupies. Graphic editor allow the user to independently choose the format for saving the image. If you are going to work with a graphic image in only one editor, it is advisable to choose the format that the editor offers by default. If the data will be processed by other programs, it is worth using one of the universal formats.
There are universal graphics file formats that simultaneously support both vector and raster images.
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