Step 1

Image, video and sound file formats

In many cases electronic publications include images, photographs and maybe some video and sound, too.

Images and photographs can be inserted into inside the actual document (e.g. publications in PostScript or PDF format) or be linked to the document (e.g. publications in HTML or SGML format).

There are dozens of different file formats for images, video and sound. Here are presented only the most common ones.

Image file formats

TIFF (Tagged Image File Format)

TIFF format is not very suitable for web publishing with HTML because WWW browsers like Netscape Navigator or Microsoft Internet Explorer can't show images as inline images in the browser window. To be able to view TIFF images from WWW, there has to be external helper application or plug-in installed in the users computer. TIFF file sizes are also usually larger than e.g those for JPEG images.

Most of the image processing programs can open TIFF images, so images can be converted into GIF or JPEG format.

JPEG (Joint Photographic Experts Group)

  • Bitmap format
  • 24-bit color
  • Compression method: JPEG, with different levels. Compression algorithm is lossy, so some information in the image is lost during compression. In most cases information lost in image is not visible to the eye.
  • Files are identified with JPG suffix
  • ftp://rtfm.mit.edu/pub/usenet/news.answers/jpeg-faq/part1

JPEG is suitable for full color or grayscale photographs. JPEG is not very suitable for line art drawings and images with large solid color areas.

JPEG is very commonly used in web publishing with HTML documents, because image file sizes are usually quite small. Almost all image processing programs can open and save JPEG format.

GIF (Graphics Interchange Format)

GIF is the most common file format for images in web publishing. GIF format is suitable for saving line art and drawings (e.g. buttons) in bitmap format. GIF format can also be used for photographs if the color depth is not very significant.

There are currently two versions of the GIF format, GIF87a and GIF89a. With GIF89a it is possible to have one color in the image to be transparent which is very useful for logos and buttons. GIF89a images can also be saved with interlace method which allows image to be loaded incrementally on the screen.

PNG (Portable Network Graphics)

  • Bitmap format
  • max. 48-bit color (grayscale images 16-bit)
  • Compression method: RLE (Run-length), lossless
  • Files are identified with PNG suffix
  • http://www.boutell.com/boutell/png/

PNG is a new format which is supposed to replace GIF format on WWW. At this moment most of the web browsers don't support PNG format as inline images, but some of the image processing programs do (e.g Paint Shop Pro 4.0 and Adobe Photo Shop 4.0).

BMP (Windows BitMap Format)

BMP is a Windows image file format. Only Microsoft Internet Explorer supports BMP images as inline images.

Summary and comparison

TIFF JPEG GIF PNG BMP
Bitmap format X X X X X
bits/pixel (max. color depth) 24-bit 24-bit 8-bit 48-bit 24-bit
Transparency

X X
Interlace method

X X
Compression ofthe image X X X X X
Suitable for...
Photographs X X (X) X (X)
Line art, drawings and images with large solid color areas

X
X
web publishing (WWW) (X) X X (X) (X)

Video and sound file formats

AVI (Video for Windows)

  • AVI (Audio Video Interleave) is Microsoft's video format. Files are identified with AVI suffix.
  • Video for Windows drivers are included in the Windows 95 operating system, and AVI files can be viewed with Windows Media Player. In Windows 3.11, Video for Windows has to be installed separately. AVI files can also be viewed with e.g. InterVU's plug-in (http://www.intervu.com/player/download.html)
  • AVI file can be linked from a HTML document with a normal <A HREF> tag or embed as inline video into a page with a <EMBED> tag.
  • AVI files can be used with PDF documents by inserting them into a PDF document in Adobe Acrobat Exchange program.
  • http://think.atr.net/mirror/faq/rtfm_mirror/FAQs/AVI_Graphics_Format_Overview.html

MPEG (Moving Picture Experts Group)

  • MPEG is a compression method for video and audio. MPEG files are identified with MPG suffix for video and MP2 or MP3 for audio.
  • MPEG video files can be viewed with e.g. InterVU's plug-in.
  • MPEG audio files (MP3) can be played with many different programs, here are some: http://barista.stanford.edu/m3c/
  • http://www.mpeg1.de/mpegfaq/

QuickTime

  • QuickTime is a video format developed by Apple. QuickTime files are identified with MOV or QT suffix.
  • QuickTime files can be viewed with the Movie Player program which can be downloaded from http://www.quicktime.apple.com/.
  • QuickTime files can be used with PDF documents by inserting them into a PDF document in Adobe Acrobat Exchange program.
  • http://www.quicktimefaq.org/the-faq/

WAV (Windows Wave Format)

  • WAV is a Windows sound format. Files are identified with WAV suffix.
  • With most sound cards some kind of software is included for digitizing and editing WAV files. Software for editing WAV files can also be found on the web as freeware or shareware programs.
  • http://www.dharbor.com/wav/faq.html

MIDI (Musical Instrument Digital Interface)

  • MIDI is like SGML of music. In comparison to digitized audio files such as WAV, MIDI files contain instructions about what is the instrument sound, its pitch and how long it will be played etc. Usually these instructions are sent to synthesizer but also soundcards can produce sound from MIDI files.
  • MIDI files are usually identified with MID suffix. MIDI files can be embedded into a HTML page with <EMBED> tag. Microsoft Internet Explorer also supports MIDI files as background sounds with e.g. <BGSOUND SRC="example.mid" LOOP=INFINITE>.
  • http://soundsolution.simplenet.com/faq.htm

Previous document: Document file formatsBack to HomepageNext document: Is the journal independent publication or electronic version of printed publication?
© 1997, VTT Information Service. Updated November 10, 1997. Teemu Rautanen