Encapsulated PostScript
Encyclopedia
Encapsulated PostScript, or EPS, is a DSC-conforming PostScript
document with additional restrictions which is intended to be usable as a graphics file format. In other words, EPS files are more or less self-contained, reasonably predictable PostScript documents that describe an image or drawing and can be placed within another PostScript document.
At minimum, an EPS file contains a BoundingBox DSC comment, describing the rectangle containing the image described by the EPS file. Applications can use this information to lay out the page, even if they are unable to directly render the PostScript inside.
EPS, together with DSC's Open Structuring Conventions, form the basis of early versions of the Adobe Illustrator Artwork
file format.
Many image converter programs can create EPS files containing the pixels of the image.
An EPS file is a stream of generic PostScript printing commands.
Thus many PostScript printer drivers have an option to save as EPS, or to add EPS DSC information to their output which you can "print to file".
Saving as EPS was a feature of Microsoft's PSCRIPT.DRV Windows printer driver and Adobe's ADOBEPS.DRV Windows printer driver for Windows versions prior to Windows 2000.
When EPS was first implemented, the only machines widely using PostScript were Apple Macintoshes. These machines could not directly render the PostScript, which presented Adobe
with the problem of how to provide a preview image while also including the actual PS version for the printer. On the Mac this turned out to be easy to solve, as the Mac file system includes two parts (known as forks) that are logically referred to as one file. By placing the PostScript in the data fork and a standard Mac PICT
resource in the resource fork
, both images could be moved about together invisibly as if they were one file. While a PICT preview often contains a bitmap
it could also contain a vector representation of the whole image, providing very high quality previews.
Neither of these technologies is commonly used on any other operating system, however. When faced with the same problems on Microsoft Windows
-based versions of their programs, Adobe chose to instead include a TIFF file encoded into the header section of the PostScript. Sometimes, though more rarely, they used the WMF (Windows Metafile
) format instead. WMF has the potential to provide vector previews, similar to PICT on the Mac. Both of these PC format EPS files have a particular disadvantage: because the PostScript data, header and preview are all in the same file, they will cause printing errors if a program does not understand the format well enough to extract only the PostScript data.
A fourth format known as a EPSI includes an ASCII
-encoded preview bitmap. This format allows for black-and-white previews only. It is mainly used on UNIX systems.
Unfortunately, with several different ways of representing the preview, they have limited portability. An application which is unable to interpret an EPS file's preview will typically show an empty box on screen, but it will be able to print the file correctly.
The most widely supported kind of preview is a Windows format preview with a TIFF.
PostScript
PostScript is a dynamically typed concatenative programming language created by John Warnock and Charles Geschke in 1982. It is best known for its use as a page description language in the electronic and desktop publishing areas. Adobe PostScript 3 is also the worldwide printing and imaging...
document with additional restrictions which is intended to be usable as a graphics file format. In other words, EPS files are more or less self-contained, reasonably predictable PostScript documents that describe an image or drawing and can be placed within another PostScript document.
At minimum, an EPS file contains a BoundingBox DSC comment, describing the rectangle containing the image described by the EPS file. Applications can use this information to lay out the page, even if they are unable to directly render the PostScript inside.
EPS, together with DSC's Open Structuring Conventions, form the basis of early versions of the Adobe Illustrator Artwork
Adobe Illustrator Artwork
Adobe Illustrator Artwork is a proprietary file format developed by Adobe Systems for representing single-page vector-based drawings in either the EPS or PDF formats...
file format.
Identifying EPS files
Because of the different ways in which EPS previews are handled, there is no one way to identify an EPS file.- A Windows-format EPS file containing a TIFF or WMF preview must start with the four bytes containing, in hexadecimalHexadecimalIn mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
, C5 D0 D3 C6. These files are widespread on all platforms. - In all other cases an EPS file must start with a line
%!PS-Adobe-a.b EPSF-c.dwhere a, b, c and d are all single digit numbers.- A Mac-format EPS file is accompanied by a resource fork. The preview is a PICT resource with ID 256. An EPS file on the Mac is expected to have a file type code of "EPSF", whether or not it has a preview.
- An EPSI file will contain a line starting
%%BeginPreview:in the DSC prolog. - In many cases no preview is present at all.
Saving to EPS file format
A number of programs will save or convert text and vector art to EPS format, including:- Adobe IllustratorAdobe IllustratorAdobe Illustrator is a vector graphics editor developed and marketed by Adobe Systems. Illustrator is similar in scope, intended market, and functionality to its competitors, CorelDraw, Xara Designer Pro and Macromedia FreeHand....
- Adobe PhotoshopAdobe PhotoshopAdobe Photoshop is a graphics editing program developed and published by Adobe Systems Incorporated.Adobe's 2003 "Creative Suite" rebranding led to Adobe Photoshop 8's renaming to Adobe Photoshop CS. Thus, Adobe Photoshop CS5 is the 12th major release of Adobe Photoshop...
(later versions) - Adobe InDesignAdobe InDesignAdobe InDesign is a software application produced by Adobe Systems. It can be used to create works such as posters, flyers, brochures, magazines, newspapers and books. In conjunction with Adobe Digital Publishing Suite InDesign can publish content suitable for tablet devices...
- CorelDRAWCorelDRAWCorelDRAW is a vector graphics editor developed and marketed by Corel Corporation of Ottawa, Canada. It is also the name of Corel's Graphics Suite...
- GhostscriptGhostscriptGhostscript is a suite of software based on an interpreter for Adobe Systems' PostScript and Portable Document Format page description languages.- Features :...
- GIMPGIMPGIMP is a free software raster graphics editor. It is primarily employed as an image retouching and editing tool and is freely available in versions tailored for most popular operating systems including Microsoft Windows, Apple Mac OS X, and Linux.In addition to detailed image retouching and...
- IDLIDL- General :* International Date Line, the time zone date boundary* Intermediate density lipoprotein* John F. Kennedy International Airport, from when it was named "Idlewild Airport" * International Drivers License...
- InkscapeInkscapeInkscape is a free software vector graphics editor, licensed under the GNU General Public License. Its goal is to implement full support for the Scalable Vector Graphics 1.1 standard....
(requires GhostscriptGhostscriptGhostscript is a suite of software based on an interpreter for Adobe Systems' PostScript and Portable Document Format page description languages.- Features :...
) - InPageInPageInPage is a page layout software for languages such as Urdu, Persian, Pashto and Arabic under Windows which was first developed in 1994. It is primarily used for creating pages in the language of Urdu, using the Nasta`līq style of Arabic script...
- Macromedia FreehandMacromedia FreeHandMacromedia FreeHand is a computer application for creating two-dimensional vector graphics that are oriented primarily to professional illustration, desktop publishing and content creation for the Web. FreeHand is similar in scope, intended market, and functionality to Adobe Illustrator, CorelDraw...
- MapleMaple (software)Maple is a general-purpose commercial computer algebra system. It was first developed in 1980 by the Symbolic Computation Group at the University of Waterloo in Waterloo, Ontario, Canada....
- MatlabMATLABMATLAB is a numerical computing environment and fourth-generation programming language. Developed by MathWorks, MATLAB allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages,...
- R (programming language)R (programming language)R is a programming language and software environment for statistical computing and graphics. The R language is widely used among statisticians for developing statistical software, and R is widely used for statistical software development and data analysis....
- MathematicaMathematicaMathematica is a computational software program used in scientific, engineering, and mathematical fields and other areas of technical computing...
- OpenOffice.org DrawOpenOffice.org DrawOpenOffice.org Draw is a vector graphics editor and is part of the OpenOffice.org office suite. It features "connectors" between shapes, which are available in a range of line styles and facilitate building drawings such as flowchart...
- PixelmatorPixelmatorPixelmator is a graphic editor developed for Mac OS X, by Pixelmator Team Ltd built upon a combination of open source and Mac OS X technologies...
- BatchPhoto
- ScribusScribusScribus is a desktop publishing application, released under the GNU General Public License as free software. It is based on the free Qt toolkit, therefore native versions are available for Linux, Unix-like operating systems, Mac OS X, Microsoft Windows, and OS/2...
Many image converter programs can create EPS files containing the pixels of the image.
An EPS file is a stream of generic PostScript printing commands.
Thus many PostScript printer drivers have an option to save as EPS, or to add EPS DSC information to their output which you can "print to file".
Saving as EPS was a feature of Microsoft's PSCRIPT.DRV Windows printer driver and Adobe's ADOBEPS.DRV Windows printer driver for Windows versions prior to Windows 2000.
EPS previews
EPS files also frequently include a preview picture of the content, for on-screen display. The idea is to allow a simple preview of the final output in any application that can draw a bitmap. Without this preview the applications would have to directly render the PostScript (PS) data inside the EPS, which was beyond the capabilities of most machines until recently.When EPS was first implemented, the only machines widely using PostScript were Apple Macintoshes. These machines could not directly render the PostScript, which presented Adobe
Adobe Systems
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...
with the problem of how to provide a preview image while also including the actual PS version for the printer. On the Mac this turned out to be easy to solve, as the Mac file system includes two parts (known as forks) that are logically referred to as one file. By placing the PostScript in the data fork and a standard Mac PICT
PICT
PICT is a graphics file format introduced on the original Apple Macintosh computer as its standard metafile format. It allows the interchange of graphics , and some limited text support, between Mac applications, and was the native graphics format of QuickDraw.The original version, PICT 1, was...
resource in the resource fork
Resource fork
The resource fork is a construct of the Mac OS operating system used to store structured data in a file, alongside unstructured data stored within the data fork. A resource fork stores information in a specific form, such as icons, the shapes of windows, definitions of menus and their contents, and...
, both images could be moved about together invisibly as if they were one file. While a PICT preview often contains a bitmap
Bitmap
In computer graphics, a bitmap or pixmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits, a spatially mapped array of bits. Now, along with pixmap, it commonly refers to...
it could also contain a vector representation of the whole image, providing very high quality previews.
Neither of these technologies is commonly used on any other operating system, however. When faced with the same problems on Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
-based versions of their programs, Adobe chose to instead include a TIFF file encoded into the header section of the PostScript. Sometimes, though more rarely, they used the WMF (Windows Metafile
Windows Metafile
Windows Metafile is a graphics file format on Microsoft Windows systems, originally designed in the 1990s. Windows Metafiles are intended to be portable between applications and may contain both vector graphics and bitmap components....
) format instead. WMF has the potential to provide vector previews, similar to PICT on the Mac. Both of these PC format EPS files have a particular disadvantage: because the PostScript data, header and preview are all in the same file, they will cause printing errors if a program does not understand the format well enough to extract only the PostScript data.
A fourth format known as a EPSI includes an ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
-encoded preview bitmap. This format allows for black-and-white previews only. It is mainly used on UNIX systems.
Unfortunately, with several different ways of representing the preview, they have limited portability. An application which is unable to interpret an EPS file's preview will typically show an empty box on screen, but it will be able to print the file correctly.
The most widely supported kind of preview is a Windows format preview with a TIFF.
See also
- PostScriptPostScriptPostScript is a dynamically typed concatenative programming language created by John Warnock and Charles Geschke in 1982. It is best known for its use as a page description language in the electronic and desktop publishing areas. Adobe PostScript 3 is also the worldwide printing and imaging...
- PDFPortable Document FormatPortable Document Format is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems....
– Portable Document Format - SVGScalable Vector GraphicsScalable Vector Graphics is a family of specifications of an XML-based file format for describing two-dimensional vector graphics, both static and dynamic . The SVG specification is an open standard that has been under development by the World Wide Web Consortium since 1999.SVG images and their...