Office of Digital Humanities
The following information was gathered from several web sites.
| Common Image Formats | |||
| Adobe Portable Document Format | Used to package text and graphics into platform-independent documents. The cross-platform Adobe Acrobat application allows virtually any computer user to read PDFs. This is the standard graphics format in Apple's operating system, OS X. | ||
| GIF* | CompuServe’s Graphics Interchange Format | .gif | Along with JPEG, one of the two original standard graphics formats on the Web. This format supports up to 256 colors (8 bits per pixel) and incorporates "lossless" compression resulting in manageble file size. That is, the original image is restored exactly upon uncompressing the file. In many cases, GIF images preserve all of the detail and color present in the original images. Supports transparency (alpha channels). |
| PNG* | Portable Network Graphics | .png | Pronounced ‘ping’. A lossless graphics format that was designed to replace the older and simpler GIF format and, to some extent, the much more complex TIFF format. It enjoys wide support by web browsers, graphics editing applications, and other applications, including LiveCode. Supports variable transparency (alpha channels), which makes it an excellent choice for images whose edges need to look smooth against any background, and for irregularly-shaped images with shadow effects. |
| JPEG* | Joint Photographic Experts Group images. | .jpeg, .jpg, .jfif | JPEG format supports full color (24-bits per pixel). It incorporates “lossy” compression. That is, the original image cannot be exactly restored when the file is decompressed. Therefore, image quality is degraded somewhat to achieve a smaller file size. However, JPEG permits very small file sizes even for fairly large full-color images and can achieve significant file compression without perceptible loss of quality. This makes the JPEG format ideal for storing photographic images. |
| TIFF | Tagged Image File Format | .tif,.tiff | The Tagged-Image File Format (TIFF) is used to exchange documents between different applications and different computer platforms. TIFF provides the maximum quality at the expense of large file sizes and thus slow transmission of images. It supports full color (24-bits per pixel). TIFF may be compressed using lossless compression. |
| BMP* | Windows Bitmapped image file | .bmp, .dib, .vga, | BMP (an abbreviation of “bitmap”) is the standard bitmapped graphics format on Windows-compatible computers. Files are usually stored uncompressed, so quality of the image remains high (a “lossless’ format) and file size tends to be large. It is an aging but still widely supported format, especially in the Windows environment. |
| PICT* | Macintosh QuickDraw/PICT format | .pict, .pict2, .pic | The PICT format is an old, mostly obsolete format that was widely used among Macintosh page layout and graphics applications as an intermediary file format used for transferring documents between applications. The PICT format was especially effective at compressing images that contain large, flat areas of color. |
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| Common Vector Graphics Formats | |||
| SVG** | Scalable Vector Graphics | .svg | Used to define vector-based graphics, defined in XML format. SVG graphics do not lose quality if resized or zoomed. |
| EPS | Adobe Encapsulated Postscript | .eps | Used in documents intended for printing. Very high quality vector graphics. |
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| Common Audio formats | |||
| AU*† | Sun Microsystems' µ-law |
.au | The early, unofficial Internet standard, developed by Sun Microsystems and used commonly on the NeXT operating system. Even though it's not the highest quality audio file format available, it's relatively small file size and the availability of players for just about every operating system made it an early favorite for Web users. At a sampling rate of 8kHz, it's sound quality is roughly equivalent to that of standard telephone receivers. |
| AIFF*† | Apple's Audio Interchange File Format | .aiff, .aif, .aifc | Also a fairly common sampled sound format. Since it is an interchange format, it is easily converted to other file formats. For these reasons, it is often used in high-end audio recording applications when storage space is not a concern. Originally developed by Apple, this format is used predominantly by Silicon Graphics and Macintosh applications. AIFF files can be quite large. One minute of 16-bit stereo audio sampled at 44.1kHz usually takes up about 10 megabytes. Supports mono and stereo samples at a variety of sample rates. Can be compressed. |
| WAVE*† | Microsoft's 16-bit RIFF format | .wav | The default audio format for Windows systems. It is very similar to the AIFF format in that it supports monaural and stereo samples and a variety of sample rates. Like AIFF, WAVE files require approximately 10mb/min for 16-bit samples with a sampling rate of 44.1kHz, but 8-bit, 8kHz, single channel versions are often offered by sites. Not easily compressed. |
| MIDI† | Musical Instrument Digital Interface | .midi, .mid | Unlike the other formats listed here, the Musical Instrument Digital Interface is not a specification for sampled digital audio. Instead, it is a serial communications protocol designed to allow the transmission of control data between electronic music instruments. It has been likened to a PostScript language for music. Since MIDI contains only instructions for controlling how and when devices, most frequently electronic synthesizers or samplers, produce sounds, the files are much smaller than digitized audio files. The MIDI Manufacturer Association (MMA), a group of electronic music instrument manufacturers, has been responsible for the evolution of the MIDI protocol since its inception in 1983. |
| SND† | Macintosh System 7 sound format | .snd | The older Macintosh sound format. These files can consist of AIFF/AIFC samples and/or of synthesized sounds that can take advantage of the System 7 sound hardware and software. Similar to .au format. |
| MP3† | MPEG Layer III | .mp3 | MPEG Layer 3 (commonly known as MP3) is a very popular standard for delivery of music on the Internet. It produces highly compressed, but still very high quality audio, most commonly around 16kBytes (128kbits) per second. These data rates don't support modem streaming, so MP3 files are generally downloaded for later playback. Virtually all commercial music players (such as iPod and Zune) support MP3. |
| AAC† | Advanced Audio Coding | .aac, .m4a | The audio part of the public MPEG 4 video standard. AAC provides audio encoding that compresses much more efficiently than older formats such as MP3, yet delivers quality rivaling that of uncompressed CD audio. This is the main format used by Apple for music downloads from the iTunes music store and in the iPod. Optionally supports Digital Rights Management (DRM). |
| WMA | Windows Media Audio | .wma | A proprietary audio compression technology introduced by Microsoft as a competitor to MP3. Delivers sound quality comparable to AAC and MP3. Performs well at lower bitrates. Supports DRM. Limited mainly to Windows OS and related products, but can be accessed by Linux and Mac OS using third-party software. |
| Ogg Vorbis | Ogg Vorbis | .ogg | Ogg Vorbis is an free, open source, lossy audio codec project headed by the Xiph.Org Foundation and intended to serve as a replacement for MP3. It gives similar compression to MP3 at equal or slightly better quality. Popularity is spreading, but nowhere near as universal as MP3. |
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| Common Motion Video Formats and Compressions | |||
| MPEG-1† | Moving Picture Experts Group movie file | .mpeg, .mpg | MPEG is an older digital motion picture compression format that is widely supported. It supports full-color, full-motion video using a lossy compression which results in quite compact files. |
| MPEG-2 | MPEG-2 movie file | .m2v, .mpeg2 | MPEG-2 is similar to the MPEG (or MPEG-1) format but includes extensions to cover a wider range of applications. This format is used for videos on DVD. |
| MPEG-4† | MPEG-4 movie file | .mp4 | MPEG-4 was defined by the Moving Picture Experts Group (MPEG), the working group within the International Organization for Standardization (ISO). Developed to be a new worldwide standard for multimedia delivery over the internet. The H.263 codec is the basis for MPEG-4. |
| H.264† | MPEG-4 AVC (Advanced Video Coding) | - | One of the most widely-used codecs available today. It enables the efficient transmission of high-quality high-definition (HD) television signals and storage of HD video on DVDs. H.264 gives excellent results across a broad range of bandwidths, from cell phones to broadcast. It has been incorporated into the MPEG-4 standard. |
| DV | MiniDV | - | The native storage format used by virtually all consumer-grade digital video cameras. Stored high quality video with very light, lossless compression. |
| QuickTime† | Apple QuickTime time-based file format | .mov, .qt | Apple Computer's multi-platform, industry-standard, multimedia software architecture.
It is used by software developers, hardware manufacturers, and content creators
to author and publish synchronized graphics, sound, video, text, music,
VR, and 3D media. Supports all major motion, still, and audio compression formats. QuickTime 4 and higher include strong support for "real" (RTSP) streaming. NOTE: Apple discontinued support for QuickTime on Mac and Windows in 2016. |
| WMV† | Windows Media Video | .wmv | A set of Microsoft proprietary streaming video technologies. Since the format is not open, WMV can only be run and edited using Microsoft software or third-party converters. |
| AVI | Video for Windows | .avi | AVI stands for Audio Video Interleave. It was primarily aimed at CD-ROM video, although it is also used on the web to some degree. It is limited in many ways. It runs on Windows only, doesn't handle audio/video synchronization as well as QuickTime and doesn't support variable-length frames. It is no longer supported by Microsoft, and is being incorporated into DirectShow. |
| RM | Real Video | .ram, .rm | A closed, proprietary streaming format developed by Real Networks for streaming audio and video over the internet. Requires Real software to run and edit. |
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