| Filename extension | .wmf, .emf, .wmz, .emz |
|---|---|
| Internet media type | image/x-wmf, image/x-emf |
| Developed by | Microsoft |
| Type of format | Image file formats |
Windows Metafile (WMF) 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.
Essentially, a WMF file stores a list of function calls that have to be issued to the Windows Graphics Device Interface (GDI) layer to display an image on screen. Since some GDI functions accept pointers to callback functions for error handling, a WMF file may erroneously include executable code.[1]
WMF is a 16-bit format introduced in Windows 3.0. It is the native vector format for Microsoft Office applications such as Word, PowerPoint, and Publisher.
In 1993, the 32-bit version of Win32/GDI introduced the Enhanced Metafile (EMF), a newer version with additional commands. EMF is also used as a graphics language for printer drivers. Microsoft recommends that "Windows-format" (WMF) functions only "rarely" be used and "enhanced-format" (EMF) functions be used instead.[2]
With the release of Windows XP, the Enhanced Metafile Format Plus Extensions (EMF+) format was introduced. EMF+ provides a way to serialize calls to the GDI+ API in the same way that WMF/EMF stores calls to GDI.
There are also compressed versions of Windows Metafiles known as Compressed Windows Metafile (WMZ) and Compressed Windows Enhanced Metafile (EMZ).[3]
Contents |
Specifications and patents [link]
The original 16 bit WMF file format was fully specified in volume 4 of the 1992 Windows 3.1 SDK documentation[4] (at least if combined with the descriptions of the individual functions and structures in the other volumes), but that specification was vague about a few details. These manuals were published as printed books available in bookstores with no click through EULA or other unusual restrictions (just a general warning that if purchased as part of a software bundle, the software would be subject to one).
Over time the existence of that historic specification was largely forgotten and some alternative implementations resorted to reverse engineering to figure out the file format from existing WMF files, which was difficult and error prone.[5] In September 2006, Microsoft again published the WMF file format specification[6] in the context of the Microsoft Open Specification Promise, promising to not assert patent rights to file format implementors.[7]
Windows Metafile vulnerability [link]
In December 2005, a vulnerability was reported to Microsoft by Symantec. By using a metafile to invoke a historic form of some printer management functions, Windows GDI could be tricked into executing data from the WMF file as code. It was assessed and classified as critical. This vulnerability was resolved in a security update on January 5, 2006 on Microsoft TechNet (MS06-001) and generally released January 10, 2006. Details can be found in Microsoft Knowledge Base Article "Vulnerability in Graphics Rendering Engine Could Allow Remote Code Execution" (912919). It was also referred to as the WMF (Windows Meta File) vulnerability.
Security expert Steve Gibson analysed the WMF vulnerability and reached the conclusion that it had been included intentionally by Microsoft as a "backdoor".[8] This was denied by Stephen Toulouse, writing officially on behalf of Microsoft,[9], and also by Microsoft employee Mark Russinovich, who explained what he said were several misunderstandings in Gibson's analysis.[10]
Alternative implementations [link]
The WMF format was designed to be executed by the Windows GDI layer in order to restore the image, but as the WMF binary files contain the definition of the GDI graphic primitives that constitute this image, it is possible to design alternative libraries that render WMF binary files, or convert them into other graphic formats. For example, the Batik library is able to render WMF files and convert them to their Scalable Vector Graphics (SVG) equivalent. The Vector Graphics package of the FreeHEP Java library allows the saving of Java2D drawings as EMF files. EMZ is an EMF file compressed with gzip.
See also [link]
References [link]
- ^ "It's not a bug, it's a feature". F-Secure. https://www.f-secure.com/weblog/archives/archive-012006.html#00000761. Retrieved 2009-10-08.
- ^ "Windows-Format Metafiles". Microsoft. https://msdn.microsoft.com/en-us/library/dd145202%28v=VS.85%29.aspx. Retrieved 2011-12-18.
- ^ "You receive a "This file is an unsupported graphic format" error message when you try to insert a picture into a PowerPoint for Mac presentation". Microsoft. https://support.microsoft.com/kb/895083. Retrieved 2008-06-01.
- ^ Microsoft Windows 3.1 Programmers Reference, Volume 4 Resources, Microsoft Press 1992, ISBN 1-55615-494-1, chapter 3 pp. 21-45
- ^ Caolan McNamara. "Window Metafile (wmf) Reference". https://wvware.sourceforge.net/caolan/support.html. Retrieved 2008-06-01. "These opcodes are unimplemented, for the reason that i dont know what they are, no known documentation"
- ^ "MS-WMF: Windows Metafile Format Specification". https://msdn.microsoft.com/en-us/library/cc215212.aspx. Retrieved 2008-06-01.
- ^ "Microsoft Open Specification Promise". https://www.microsoft.com/interop/osp/. Retrieved 2008-06-01.
- ^ Steve Gibson. "Security Now, Issue #22, The Windows Metafile Backdoor?". https://www.grc.com/securitynow.htm#22. Retrieved 2010-06-11. "'"
- ^ https://blogs.technet.com/b/markrussinovich/archive/2006/01/18/inside-the-wmf-backdoor.aspx
- ^ "Inside the WMF Backdoor"
External links [link]
- Windows Metafile Format Specification from Microsoft
- MSDN: Windows GDI- Metafiles
- File Format Summary at fileformat.info
- Windows Metafile FAQ
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https://wn.com/Windows_Metafile
EMF
EMF may stand for:
Music
- "EMF", a bonus track on EMF's album Schubert Dip
Organizations
Physics
Fiends (album)
Fiends is the third album from the post-hardcore band Chasing Victory, released only months before the band officially broke up. This album is a change of style for the band. While their debut and EP had a solid post-hardcore sound similar to that of Glassjaw and Thursday, the sound for this album was changed. The band experimented with Southern rock, post-grunge, and even rock and roll, while still retaining their post-hardcore roots.
Track listing
Demon (novel)
Demon is a Locus nominated 1984 science fiction novel by John Varley. It is the third and final book in his Gaea Trilogy.
Plot summary
Demon takes place in the years 2113 through 2121, thirteen to twenty-one years after the events of Wizard. Cirocco Jones has become a combination fugitive and resistance leader, staying alive in spite of the forces of Gaea by virtue of her unusual abilities, and with the help of friends and allies. These include the race of Titanides, who remain loyal to the Captain, as they call Jones, rather than to Gaea; and the race of Angels, who call her the Wing Commander. The militant creations of Gaea, once limited to the buzz-bombs, have expanded to include horrifying beings called Priests, each one made by Gaea from parts of her human victims. The Priests, named after significant religious figures from the past, carry out her dirty work as a class of undead field commanders, supported by bands of zombies. These are made from the corpses of humans who die in the wheel and — unless cremated — become infested with creatures called deathsnakes and arise to walk again as zombies.
Screamin' Demon
The Screamin' Demon was a shuttle loop roller coaster at Kings Island in Mason, Ohio. Designed by Arrow Development, it opened in 1977 as one of the first looping roller coasters in the United States to run both forward and backward. After ten years of operation, the ride was moved to Camden Park.
History
Anton Schwarzkopf and Intamin AG co-developed the first shuttle loop design, which opened as King Kobra at Kings Dominion in 1977. A total of six shuttle loop roller coasters opened that same year throughout the United States. Screamin' Demon had the distinction of being the first from Arrow Development to open to the public. Unlike the vertical tracks used as reverse points at both ends on the King Kobra, Arrow used loading platforms instead.
At the end of the 1987 season, the ride was sold and relocated to Camden Park in West Virginia where it was renamed to Thunderbolt Express. It was closed in 2000 and never reopened. It was eventually scrapped in 2004.
