9 Apr 1995

Viewers

DOS and Unix were dominated by character mode screens and ordinary text editors. Windowed systems have only recently come into wide use. In the same way, the Internet has traditionally been dominated by plain text. However, as documents are now word processed or desktop published with graphics, tables, and other elements of visual interest, so the network has begun to transmit pictures, drawings, maps, music, movies, and other multimedia formats.

Unfortunately, there are many formats and tools for more complicated data. Sound will be recorded differently for low grade voicemail and high grade stereo music. Documents can be stored in word processing (input) format or as formatted PostScript output.

Consider image data, such as those developed by the refurbished Hubbell Space Telescope. The most important thing about space is that it is mostly Black. This means that almost every telescope image can be compressed substantially. The TIFF standard for images and compression is commonly associated with scanners and some photographs. It can be used for black and white or can represent colors exactly. The GIF format was developed by CompuServe for PCs and is limited to 256 colors (a common limit for Windows screen drivers). The JPEG standard reduces the size of the files even more, by compressing out features that the human eye will not notice from a normal viewing distance. An astronomer wishing to do computerized analysis of the image would certainly want the original data, and that calls for some format similar to TIFF. For casual display, however, JPEG is much more compact.

There are many utility programs that read in images in any of several formats, display them on the screen, manipulate them, and save the results. One common problem, for example, is to convert color images to a form that prints well on a black and white laser printer. This utility would be needed anyway, with or without the Internet.

It therefore does not make sense for Internet client programs of FTP, Gopher, or WWW protocols to each contain their own logic to handle different file formats, compression techniques, and conversions. Instead, the Internet programs fetch data from servers on the network, write temporary files on disk, and then invoke utilities to display or process the data. Such utilities are called viewers.

One of the options of the Windows File Manager is to "associate" a viewer program with datasets having a particular extension. The WRI extension means a Window Write file, DOC may be a Word document, PPT is a PowerPoint presentation. Using the file manager, these associations can be extended to other programs and other sorts of data. GIF, TIF, BMP, and JPG files can be associated with a bitmap image viewer such as WINGIF or LVIEW. PS (PostScript) files can be associated with one of the Ghostscript programs.

The network navigational tools (FTP, Gopher, WWW) can be similarly configured to launch a viewing program after fetching a file through the network. The WS_FTP program uses the same associations established by the File Manager for local files. The Gopher client and Web browsers generally have to be configured separately.

There are freeware viewers for most data types. However, a more sophisticated shareware or even a program product might be used when a particular type of data is used extensively. By separating the issues of data viewing from network browsing, each user is granted freedom of choice.

Of course, "freedom of choice" also translates into "you have some work to do." Nobody can put together a single correct package of viewers. There are several file servers that distribute sound files, but it only makes sense to install a sound utility on machines that have a multimedia sound card installed. Windows on the World can only do part of the configuration automatically. The rest you may have to do for yourself using Windows Notepad or some other favorite editor.

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Copyright 1995 PC Lube and Tune -- Windows on the World -- H. Gilbert