Each of us, one way or another, is faced with 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 this or that type of information.
What are image formats?
This is information stored in a file that is intended for data visualization (displaying it on a reproducing 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 rendering method, 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 bitmap graphics
First, let's consider what image formats are used exclusively in the standard understanding of graphics. It is necessary to clearly distinguish between vector and raster graphics. These two types are basic.
Vector graphics allow visualization of 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 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 of individual elements without significantly increasing the final file size. In addition, scalability is very much manifested here, which allows you to resize each individual element or their entire collection without losing the quality of the entire image. Such a descriptive algorithm is mainly suitable for graphics created by hand, for example, in some kind of graphics editor. This method is not applicable for photographs.
PCX is a format for storing bitmap images with a color depth of 24 bits. Compression is very fast, but not suitable for converting detailed graphics such as photographs.
RAW is a versatile format used for images taken directly from digital cameras. We can say about it that this is the format of the best image quality. It can serve as a source material for processing not only images, but also sound. In addition, the support for metadata provides tremendous 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 graphics editors
In addition to the standard types, it is possible to 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 assumes the use of different compression methods for each specific element contained in the final file. Today it is universal mainly for technical documentation in electronic form.
CDR is a vector format of the graphics editor Corel Draw. It can only be processed with such a software package. Not supported by other editors, but easily exported to other formats.
AI is an Adobe Illustrator format supported by most other editors. The main feature is the highest image stability and full compatibility with PostScript technology. It can be used as an intermediate format when translating from one to another.
PSD is the best image format in Adobe Photoshop for intermediate editing of complex images. Allows layers and blending modes, but is larger than other formats. As the final format for saving files, it is used exclusively in the program itself.
Large format images
If we talk about a large format, where you need to take into account high detail, then you should use RAW, TIFF or PSD.
However, many professional photo and video cameras with matrices of 20-25 megapixels have their own standards. Most of them are adapted to the most common types of formats. It all depends on the settings of the camera itself. The same goes for mobile devices.
Basic types of video and animation
Now let's briefly dwell on the video, since it can also in a sense be interpreted as an image, or rather, as a set of alternating images (frames). Here, the determining factor is the frame rate per second (fps) and the size of the picture in pixels.
Initially, at the dawn of digital video development, it was the well-known AVI format, which is still used today, since it is a kind of container containing information processed or compressed by 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 high-definition TV picture formats that allow you to play files with HD, Full HD (2k) or Ultra quality standards. HD (4k).
When it comes to animation, Flash is the most well-known technology today. Initially, it was a development of the Macromedia corporation, but then it was bought by Adobe and significantly modernized. The format of these files is SWF. It is mainly used to create small animation videos, computer animation, banners or for simple games.
Mobile systems
If we talk about mobile systems (smartphones or tablets based on Android, 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 video will not play. That is why you will have to solve the problem of converting the source material to another type.
For example, regular phones only accept 3GP format. Android or iOS recommend using MP4. But in general, there are enough options.
Changing the basic parameters of images
Probably everyone understands perfectly well that editing needs to be done using special programs.
The simplest operations for resizing, reflecting, rotating, tilting and others can be performed even in the most primitive Paint editor, which is included with any Windows operating system.
If more complex actions are required, for example, changing color, saturation, contrast, editing layers, splitting an 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 the standard features, they can use specialized effects and modeling systems that allow transferring a real image to a pre-built mathematical model, similar to how the battle between Morpheus and Neo was filmed in the first part of The Matrix.
Format conversion
Conversion (converting) is performed using utilities called converters. One of the most prominent representatives is Xilisoft Video Converter, which can convert both graphics and video.
For graphics, you might 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 to look out for is the final format and the possible loss of quality (image compression formats). When viewing a picture or video on a smartphone or tablet, it will not be so noticeable, but on the TV panel, the difference will become very noticeable.
What is the preferred format 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. It is better to use original camera formats here.
When converting one format to another, it will sometimes be simply impossible to restore the "source", so when submitting files to the studio, it is not recommended to change their initial appearance. An exception if you have the necessary knowledge and edit yourself using professional software.
The same goes for videos. It all depends on what device it will be viewed on.
Conclusion
There are many and varied image formats, including graphics and video. The article reviewed the most popular formats. The questions of their processing and transformation, the choice of software, the format used for storing data, etc., each user decides for himself.
GIF(Graphics Interchange Format)The GIF format was developed in 1987 by the computer information service CompuServe. Advantages
- Small size, which is achieved by a limited color gamut - no more than 256 colors.
- Transparent background.
- Animation.
The fruit of the community of independent programmers is the response to the transition of the popular GIF format to the category of commercial products. The PNG format does almost everything that the GIF format does, with the exception of animation. Advantages
- Best Data Compression - Compresses bitmaps 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.
That allows you to save photographs and complex drawings in this format. Advantages
- Full color palette.
- High-quality transparency allows you to superimpose the picture on any background
To find the best way to compress photographic quality images, two standards organizations - the International Telecommunications Union (ITU) and the International Organization for Standartization (ISO) - created the Joint Photographic Experts Group (JPEG).
Uses lossy compression. This compression removes the information that is irrelevant to the perception of the image. WBMP(WAP BitMap)
monochrome (two-color) images.
The maximum size of a picture should not exceed the limits on the size of the card - 1.5 KB. BMP(BitMap)
The simplest bitmap format, BMP, is the native Windows format. BMP stores color data only in RGB, which means that this format is designed for use on screen. PCX(PCExchange)
PCX images can be viewed by most DOS programs. Like BMP, 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 image quality. Due to its compatibility with most professional image processing software, TIFF is very convenient for 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 sensor at the time of shooting, consists of three photographs taken in red, blue and green colors.
RAW file extensions may vary from manufacturer to manufacturer and may not always be able to be opened with image processing software.
Although if the camera supports saving RAW, then, as a rule, it comes bundled 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 suppliers 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 a relatively low stability and problems with the compatibility of files of different versions of the format. Ai(Adobe Illustrator)
As 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. It is understood by almost all Windows programs that are somehow related to vector graphics. EMF(Enhaced Metafile)
Similar to WMF.
OTHER FORMATS
SWF(ShokWaveFlash)Flash format, a product of the Macromedia company, which allows the development of interactive multimedia applications. Flash is used in a variety of ways, including 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 using PHP and XML.
SVG(Scalable Vector Graphics) A standard recommended by the World Wide Web Consortium for describing 2D vector and combined vector-raster graphics using XML markup.
In the browser, SVG graphics are rendered using bitmap engines. Support for translucencies in each layer, linear gradients, radial gradients, visual effects (shadows, hillshades, shiny surfaces, textures (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 the SVG file, you can create 3D animated images.
A bitmap can be embedded in SVG, which, like any other object in SVG, can be transformed, transparent, etc. ICO(Icon)
Icons are used in all kinds of programs on a computer, smartphone. But the average person usually needs to create or use an icon on their website.
Many people try to start their own website. Even if you are using a ready-made website template with a style that only needs to be filled, it would still be good for you to make a unique icon. The Internet icon is used as a symbol of the site, a logo. For example, now you see a red square in the address bar. If you add a page of our site to your favorites (favorit), 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 the icon on the Internet.
PostScript
EPS(Encapsulated PostScript)The most reliable and versatile way to save data. It uses a simplified version of PostScript, it cannot contain more than one page in one file, does not store a number of settings for the printer. As with PostScript print files, EPS records the final work, although programs such as Adobe Illustrator and Adobe Photoshop can use it as a workspace. EPS is intended for transferring vectors and rasters to publishing systems, and is created by almost all programs that work with graphics.
WHAT FORMAT TO CHOOSE?
| For internet | |
| a photograph or drawing with flowing tones | Jpeg |
| a picture with straight lines, small color range, with even fill (no gradient) |
GIF PNG image |
| 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, just not of low quality | Jpeg |
| For the printing house and for the original of the best quality | RAW |
File formats are the foundation for working with digital photos. will guide you through all the major graphic file formats.
RAW.
A file format containing raw information coming directly from the camera's image sensor. These files are not processed by the camera's processor (unlike JPG) and contain the original shooting information. RAW can be compressed without loss of quality.
The advantages of RAW are obvious - unlike JPG, which was processed in camera and already saved with data compression - RAW provides the broadest possibilities for photo processing and retains the highest quality.
The note. Different camera manufacturers use different algorithms to create RAW in their cameras. Each manufacturer comes up with their own resolution for their RAW file - NEF - Nikon, CR2 - Canon ...
JPEG (aka JPG).
This is the most common graphics file format.
JPG has earned its popularity for its flexible data compression capabilities. If necessary, the image can be saved with maximum quality. Or compress it to the minimum file size for transmission over the network.
JPG uses a lossy compression algorithm. What does it give us? A clear disadvantage of such a system is the loss of image quality every time a file is saved. On the other hand, compressing the image 10 times simplifies data transfer.
In practice, saving a photograph with a minimum compression ratio does not result in any visible degradation in image quality. That is why JPG is the most widespread and popular format for storing graphic files.
TIFF.
The TIFF format is very popular for storing images. It allows you to save photos in different color spaces (RBG, CMYK, YCbCr, CIE Lab, etc.) and with a large color depth (8, 16, 32 and 64 bit). TIFF is widely supported by graphics applications and is used in the printing industry.
Unlike JPG, a TIFF image will not lose quality after each file save. But, unfortunately, it is because of this that TIFF files weigh many times more than JPG.
The TIFF format is currently owned by Adobe. Photoshop can save TIFF without merging layers.
PSD.
The PSD format is used in Photoshop. PSD allows you to save a raster image with many layers, any color depth and in any color space.
Most often, the format is used to save intermediate or final results of complex processing with the ability to change individual elements.
PSD also supports lossless compression. But the abundance of information that a PSD file can contain greatly increases its weight.
BMP.
BMP format is one of the first graphic formats. It is recognized by any program that works with graphics; format support is integrated into Windows and OS / 2 operating systems.
BMP stores data with a color depth of up to 48 bits and a maximum size of 65535 × 65535 pixels.
At the moment, the BMP format is practically not used either on the Internet (JPG weighs several times less), or in printing (TIFF copes with this task better).
GIF.
The GIF format was created at the dawn of the internet for the exchange of images. It can store losslessly compressed images in up to 256 colors. GIF format is ideal for drawings and graphics, and also supports transparency and animation.
GIF also supports lossless compression.
PNG.
The PNG format was created to both improve and replace the GIF format with a graphics format that does not require a license to use. Unlike GIF, PNG has alpha channel support and the ability to store an unlimited number of colors.
PNG compresses data losslessly, which makes it very convenient for storing intermediate versions of image processing.
JPEG 2000 (or jp2).
New graphics format created to replace JPEG. For the same quality, JPEG 2000 file size is 30% smaller than JPG.
When compressed strongly, JPEG 2000 does not split the image into the squares typical of the JPEG format.
Unfortunately, at the moment this format is not widely used and is only supported by Safari and Mozilla / Firerox browsers (via Quicktime).
Knowledge of file formats and their capabilities is one of the key factors in prepress, preparing 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 company producing image editors considered it their duty to create their 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 passed natural selection, has proven its viability and usefulness. All of them have some characteristic features and capabilities that make them indispensable in work.
Knowledge of the peculiarities, subtleties of technology is important for a modern designer, just as it is necessary for an artist to understand the differences in the chemical composition of paints, properties of soils, types of metals and wood species.
The main purpose of Knowledge, by and large, is the expansion of a person's capabilities, an increase in the degree of his freedom, when a person acts as he sees fit, and not as forced by his circumstances.
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 mathematical descriptions of objects relative to the origin. Simply put, in order 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 set for the arc, etc.
Thus, a vector illustration is a collection of geometric primitives. Most vector formats can also contain raster objects embedded in the file or a link to the raster file (OPI technology).
The difficulty in transferring data from one vector format to another lies in the use of different algorithms by programs, different 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. In the process of printing to the printer, the sketches are replaced with the original files. The use of OPI, instead of simple embedding, makes it possible to save computer resources (first of all, memory), significantly increasing its performance. OPI is the main work with imported graphic files in programs such as FreeHand and QuarkXPress, and is widely used in other products.
The bitmap file is simpler (for understanding, at least). It is a rectangular matrix (bitmap), divided into small squares - pixels (pixel - picture element). Raster files can be divided into two types: for display and for printing.
The resolution of files of such formats as GIF, JPEG, BMP depends on the video system of the computer. Older Macs used 72 pixels per square inch (screen resolution), Windows did not have a uniform standard, but today the most commonly used value is 96 pixels per square inch of the screen. In reality, however, these parameters have now become rather arbitrary, since almost all video systems of modern computers allow you to change the number of pixels displayed on the screen.
Raster formats designed solely for display only have a screen resolution, that is, one pixel in a file corresponds to one screen pixel. They are also printed at screen resolution.
Raster files intended for prepress of publications have, like most vector formats, the Print Size parameter - the print size. Associated with it is the concept of print resolution, which is the ratio of the number of pixels per square inch of the page (ppi, pixels per inch, or dpi - dots per inch, - the term is not entirely correct, but often used).
The print resolution can be from 130 dpi (for newspaper) to 300 (high quality printing), more is almost never needed.
Raster formats also differ from each other in their ability to carry additional information: various color models, vectors, alpha channels or channels of spot colors, layers of various types, leading (interlaced loading), animation, compression options, and more.
GIF (CompuServe Graphics Interchange Format)
The hardware agnostic GIF format was developed in 1987 (GIF87a) by CompuServe for transferring bitmap images over networks. In 1989, the format was modified (GIF89a), and support for transparency and animation was added. GIF uses LZW compression, which allows you to compress files with a lot of homogeneous fills (logos, labels, schemes) quite well.
The LZW (Lempel-Ziv-Welch) compression method was developed in 1978 by the Israelis Lempel and Ziv and later refined in the United States. Compresses data by searching for identical sequences (called phrases) throughout the file. The identified sequences are stored in a table, and shorter markers (keys) are assigned to them. So, if the image contains sets of pink, orange and green pixels that are repeated 50 times, LZW detects this, assigns this set a separate number (for example, 7) and then stores this data 50 times as number 7. LZW method, also Like RLE, it performs better in areas of uniform, noise-free colors, it performs much better than RLE when compressing arbitrary graphics data, but the encoding and decompression process is slower.
GIF allows you to record an image "through a line" (Interlaced), due to which, having only a part of the file, you can see the whole image, but at 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 end of the download of the file, the user can understand what is inside and decide whether to wait for the entire file to be uploaded. Interlaced writing slightly increases the file size, but this is usually justified by the acquired property.
In GIF`e you can assign 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 may contain not one, but several raster images that 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.
Read also:
- D. Kirsanov "Inexhaustible GIF"
- A. Lebedev "A simple secret of GIF"
- A. Lebedev "The Complicated Secret of GIF"
JPEG (Joint Photographic Experts Group)
Strictly speaking, JPEG is not a format, but a compression algorithm based not on finding identical elements, as in RLE and LZW, but on the difference between pixels. Data encoding takes place 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.
A set of numbers is formed for each block. The first few numbers represent the color of the block as a whole, while the subsequent numbers represent the subtle ones. The spectrum of detail is based on human visual perception, so large details are more visible.
In the next step, depending on the quality level you choose, a certain portion of the numbers representing subtle details are discarded. The last stage uses Huffman coding to compress the final data more efficiently. Data recovery is performed 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, however, it is relatively new and not understood by old programs (until 1995). JPEG does not support indexed color pickers. Initially, CMYK was not included in the format specifications, Adobe added support for color separation, but CMYK JPEG makes problems in many programs. The best solution is to use JPEG compression in Photoshop EPS files, which is described below.
There are JPEG sub-formats. Baseline Optimized - files are slightly better compressed, but not readable by some programs. JPEG Baseline Optimized is designed specifically for the web and is supported by all major browsers. Progressive JPEG is also designed specifically for the Web, its files are smaller than standard ones, but slightly more Baseline Optimized. The main feature of Progressive JPEG is its support for interlaced analog output.
From what has been said, the following conclusions can be drawn. JPEGs are better at compressing photo-quality bitmap images than logos or schemes - they have more grayscale transitions, and unwanted noise appears among monophonic fills. Large images for the web or with a high print resolution (200-300 or more dpi) are compressed better and with less loss than with a low one (72-150 dpi). in each square of 8x8 pixels, 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 rendition (reproduction) are important, since color information is discarded during compression. In JPEG, you should save only the final version of the work, because each resave leads to more and more data loss (discarding) and the transformation of the original image into a mess.
The LAB color space represents color in three channels: one channel is dedicated for luminance values (L - Lightnes) and two others for color information (A and B). Color channels correspond to a scale, not just one color. Channel A represents a continuous spectrum from green to red, while channel B from blue to yellow. Average values for A and B correspond to real shades of gray.
There is a similar YCC color model used in the Kodak Photo CD and FlashPix formats not described here.
The Huffman compression method was developed in 1952 and is used as part of a number of other compression schemes such as LZW, Deflation, JPEG. In the Huffman method, a set of symbols is taken and analyzed to determine the frequency of each symbol. The most common 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 lossless compression Deflate, similar to LZW (it was because of the patenting in 1995 of the LZW algorithm that PNG was born). Compressed indexed PNG files are generally smaller than their analogous GIFs; 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, like in GIF, slightly increases the file size. Unlike GIF, where transparency is like honey - either there is or not, PNG also supports translucent pixels due to the Alpha channel with 256 grayscale.
The gamma correction information is written to the PNG file. Gamma is a certain number that characterizes the dependence of the brightness of the glow of your monitor screen on the voltage at the kinescope electrodes. This number, read from the file, allows the display brightness to be corrected. It is needed so that the picture created on Mac looks the same on Windows and on various UNIX. Thus, this feature helps to implement the main idea of the WWW - the same display of information regardless of the user's hardware.
PNG is supported in Microsoft Internet Explorer from version 4 on Windows and from version 4.5 on Macintosh. Netscape added PNG support to its browser in versions starting with 4.0.4 for both platforms. However, there is still no support for such important format functions as fading transparency and gamma correction.
Read also:
M. Tiguleev "PING"
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. TIFF is generally the best choice when importing bitmap graphics into vector programs and publishing systems. It has the full range of color models from monochrome to RGB, CMYK and additional spot colors. TIFF can contain clipping paths, alpha channels, layers, and other additional data.
The exception, to some extent, is FreeHand. Sometimes TIFF files in it can arbitrarily change their location when creating a PostScript file or directly in a document when opened. More often than not, TIFFs "jump" while in a clipping path. With FreeHand, it is still preferable to use EPS.
TIFF can be saved in two write orders: Macintosh and PC. This is because Motorola processors read and write numbers from left to right, while Intel processors do the opposite. 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. Some older software (eg QuarkXPress 3.x, Adobe Streamline, many text recognition software) cannot read compressed TIFF files, however if you are using newer software there is no reason not to use compression.
Adobe PostScript
PostScript is a page description language (laser printer control language) from Adobe. It was created in the 80s to implement the principle of WYSIWYG (What You See is What You Get). 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 the Print to File function of graphics programs using a PostScript printer driver.
Such files contain the document itself (only what was on the pages), all associated files (both bitmap and vector), used fonts, as well as other information: color separation boards, additional boards, screen frequency and raster dot shape for each board and other data for the output device. If the file is created correctly, it doesn't matter what platform it was made on, True Type or Adobe Type 1 fonts were used - it doesn't matter.
However, it should be borne in mind that even if you made the correct settings in the print window, problems may arise associated with incorrect translation of the program you are using of its graphic language into PostScript (for example, embedding information about unused fonts). The most correct PS files are created by Adobe programs.
The data in a PostScript file is usually written in binary encoding (Binary). Binary code takes up half as much space as ASCII. ASCII encoding is sometimes required for transferring files over networks, for cross-platform exchange, for printing over serial cables. In the above cases, the binary encoding may be distorted (which will make the file unreadable) or cause "strange" behavior of the file server. These problems have long been eliminated in modern systems, but older computers and servers are prone to them.
This 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 closing for printing from various programs, you can find on my website in the article "Ugly PostScript".
EPS (Encapsulated PostScript)
The Encapsulated PostScript format can be called the most reliable and versatile way to save data. It uses a simplified version of PostScript: it cannot contain more than one page in one file, does not store a number of settings for the printer. As with PostScript print files, EPS records the final work, although programs such as Adobe Illustrator and Adobe Photoshop can use it as a workspace.
EPS is intended for transferring vectors and rasters to publishing systems, and is created by almost all programs that work with graphics. It only makes sense to use it when outputting to a PostScript device. EPS supports all color models necessary for printing, among them, such as Duotone, can also record data in RGB, clipping path, information and trapping and rasters, embedded fonts. In EPS format, the data is saved in the Clipboard of the Adobe program for exchange with each other.
You can save a thumbnail (image header, preview) with the file. This is a low-resolution copy in PICT, TIFF, JPEG or WMF format, which is saved along with the EPS file and allows you to see what is inside, since only Photoshop and Illustrator can open the file for editing. Everyone else will import the sketch, replacing it with the original information when printed on a PostScript printer. On a non-PostScript printer, the sketch itself is printed. If you are using Photoshop for Mac, save your 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 on a PC or don't know where the file will be used, save your thumbnail in TIFF format (when given a choice). CorelDRAW also offers the WMF vector format for sketching, you should be very careful about using this brainchild of Microsoft - it will not bring you to any good.
Initially EPS was developed as a vector format, later its raster version - Photoshop EPS - appeared. In addition to the type of thumbnail (TIFF, PICT, JPEG) Photoshop allows you to choose the method of data encoding. ASCII, Binary and JPEG. The first two were described above, JPEG is worth stopping at.
Photoshop allows you to compress bitmap data using the JPEG algorithm. Adobe has improved this compression method. Now, JPEG, performed by Photoshop, supports CMYK and compresses better than JPEG, which fully meets the original specifications. In other words, JPEG-encoded EPS files without thumbnail weigh less than similar JPEG files! However, I would like to draw your attention to an important feature in working with JPEG compression to EPS.
Printer and photosetter drivers cannot separate these files. That is, when you perform color separation on your computer, the EPS-image with JPEG compression will be entirely on the first card (Cyan, usually). However, in the service bureau, Scitex workstations (most of them in Israel) can color-separate pages with JPEG EPS illustrations without any problems. Systems of other companies, I think, also support JPEG EPS, in any case it is worth inquiring. In Tel Aviv service bureaus and printing houses, I was often recommended to use JPEG EPS instead of TIFF for recording raster data, since it is faster to output.
EPS has many flavors, depending on the creator program. The most reliable EPS is created by programs produced by Adobe Systems: Photoshop, Illustrator, InDesign. Since 1996, Adobe programs have a built-in PostScript interpreter so they can open EPS and edit them. This opportunity seems to me very important. 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 Save Page As EPS, and FreeHand editable EPS, created by Save As. Do not particularly trust Corel's EPS version 6 and below and EPS from CorelXARA. EPS files from CorelDRAW 7 and above still have the problem of adding margins to the Bounding Box (a conditional rectangle in PostScript that describes all objects on the page).
Before exporting from CorelDRAW, CorelXARA and, to a lesser extent, from FreeHand EPS files, it is worth converting many program effects (translucent fills, for example) into raster or simple vector objects. Thick contours (more than 2 pt), perhaps, makes sense to convert to objects as well, when the program provides such an opportunity. You can check the EPS file in 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 layout and graphics over networks. Used as an internal graphics format in Mac OS X.
PDF files are created by converting from PostScript files or by exporting a number of programs. Adobe Acrobat Distiller is used for conversion, this is the best way to create PDF. Creating PDF by exporting from programs usually gives the worst result - the files are heavier, 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 the quick production of simple text documents. It has the same font embedding problem 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 with the Adobe Acrobat package.
PDF was originally designed as a compact format for electronic documentation. Therefore, all data in it can be compressed, and different types of compression that are most suitable for them are applied to different types of information: JPEG, RLE, CCITT, ZIP (similar to LZW and also known as Deflate). Acrobat Exchange 3 (which in the 4th version has become simply called Acrobat 4.0) allows you to arrange hyperlinks, fillable fields, include video and sound in the 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 encoding. CCITT Group 3 is identical to fax format, CCITT Group 4 is fax format, but without special control information.
The PDF file can be optimized. Duplicate elements are removed from it, the page-by-page order of loading pages through the web is set, with priority first for text, then graphics, and finally fonts. However, when there are no duplicate elements, the file, after optimization, usually grows slightly.
PDF is increasingly used for transmission over networks in compact graphics and layout. It can store all the output device information that was in the original PostScript file. This applies to PDF versions 1.2 (Acrobat 3) and higher. However, version 1.2 cannot include trapping information, some other specific data (DSC, for example) does not use color profiles. All this is implemented in the following format options.
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
The PostScript file intended for output goes through a series of stages on its way to the phototypesetting machine. The most important of these is rasterization, the process of converting PostScript data to a bitmap by the PostScript interpreter (RIP).
CorelDRAW files can be used to transfer / transfer works to a PC, but it is not desirable to import them into layout programs. On Mac, CorelDRAW for Windows files open the Mac version of CorelDRAW and Adobe Illustrator 8 and above.
PICT (Macintosh QuickDraw Picture Format)
PICT is a proprietary Mac OS Classic format. The standard for the clipboard, uses the graphical language of the Mac OS. PICT is capable of carrying raster, vector information, text and sound, uses RLE-compression. Supported on Mac by all programs. Pure bitmap PICT files can be of any bit depth (from Lineart to CMYK).
Vector PICT files, which are almost extinct these days, had strange problems with line width and other printing anomalies.
The format is used for the needs of Mac OS, and when creating certain types of presentations, only for Macintosh. Outside of the Macintosh, PICT has the extension .pic or .pct and is readable by separate programs, but it is rarely simple and straightforward to work with.
WMF (Windows Metafile)
The vector format WMF uses the graphics language of Windows and can be said to be its native format. Serves to transfer vectors through the Clipboard. It is understood by almost all Windows programs that are somehow related to vector graphics.
However, despite the seeming simplicity and versatility, it is worth using the WMF format only in extreme cases for transferring "naked" vectors. WMF distorts color, cannot save a number of parameters that can be assigned to objects in various vector editors, cannot contain raster objects, is not understood by many Macintosh programs.
BMP (Windows Device Independent Bitmap)
Another native Windows format. It is supported by all graphics editors running this operating system. It is used to store bitmaps intended for use in Windows and, in fact, is not suitable for anything else.
It is capable of storing both indexed (up to 256 colors) and RGB color (over 16 million shades). It is possible to use compression according to the RLE principle, but it is not recommended to do this, since many programs do not understand such files (they may have the .rle extension). There is a variation of the BMP format for the OS / 2 operating system.
Using BMP outside of Windows is a common newbie mistake. It is important to understand that it is not desirable to use BMP either on the web, or for printing (especially), or for simple transfer and storage of information.
RTF (Microsoft Rich Text Format)
The RTF text format got here for its extraordinary ability to transfer text from one program to another. It allows you to transfer formatted text from OCR or word processing programs to graphics programs or in any other direction. RTF can be a good solution (and sometimes the only way out) when transferring from program to program non-Latin, for example, Hebrew or Russian text in Windows 95/98 Hebrew Edition.
The secret to compatibility is the use of special RTF and Unicode formatting tags. It is Unicode (used as the basis of the Microsoft Word 97/98 format for Macintosh and PC) that makes it easy to transfer Russian texts from PC to Mac and back in MS Word 97/98 files (also true for higher versions of Word).
RTF is used as the main text in the TextEdit that comes with Mac OS X and the WordPad software that comes with Windows.
Vector Formats Vector format files are especially useful for storing linear elements (lines and polygons), as well as elements that can be decomposed into simple geometric objects (for example, text). Vector files do not contain pixel values, but mathematical descriptions of image elements. Based on mathematical descriptions of graphic shapes (lines, curves, splines), the visualization program builds an image.
Vector files are structurally simpler than most raster files and are usually organized as streams of data.
Examples of the most common vector formats are AutoCAD DXF and Microsoft SYLK.
WMF. It is a vector format used by Windows graphics programs. This format is used to transfer vector images via the clipboard in the Windows environment. This format is accepted by almost all vector graphics programs. You cannot use this format for bitmaps. Disadvantages: color distortion and non-preservation of a number of parameters that are set for images in graphics programs.
AI. Internal format of Illustrator. It can be opened with Photoshop and besides this format is supported by all programs related to vector graphics. This format is the best way to transfer vector images from one program to another. Raster graphic elements are lost in most cases when transferred via AI-format.
CDR. This is the internal format of Corel Draw. This format is very popular, like the software package itself. Many programs can import vector files into Corel Draw formats. The CDR format also contains raster graphic objects. This format uses compression, with different compression applied to vector and bitmap files.
Metafile formats
Metafiles can store both raster and vector data. The simplest metafiles resemble vector files; they contain the language or syntax for defining vector data items, but can also include a bitmap representation of an image. Metafiles are often used for transporting raster and vector data between hardware platforms, as well as for moving images between software platforms.The most common metafile formats are WPG, Macintosh PICT, and CGM.
