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Decoding & Viewing Image Files

This section is mostly for those of you who are new to the Usenet groups. My thanks to my friend Josh for the sections on Macintosh procedures.

Since ABPC is a usenet group, it was part of a system design that was originally intended for text posts, not binaries. Binaries (images and programs) were *not* originally intended to be distributed through the usenet.

ASCII versus Binary

Without getting too technical, suffice to say that text files use the ASCII characters only ("7-bit"), which are "readable" characters. If you were to "look" at an ASCII file, you would recognize all the characters as being alpha-numeric. Programs and images, on the other hand, use "8-bit" characters. These include all of the ASCII characters, plus about 100 additional ones which are not "viewable" by a text editor (what you see are a bunch of weird characters).

Since the Usenet was written to allow 7-bit/ASCII characters only, but images are 8-bit, it seems that there is a conflict. To resolve this conflict, images/programs must be *converted* to ASCII before posting to the Usenet. However, this means that to view the images, they must first be converted back to 8-bit.

Encoding of files

The most common method for encoding/decoding is UU. A UUencoded file can be recognized by the fact that every line of data begins with the letter "M" and the header for the file gives the filename.

Another common method for encoding/decoding is Mime/Base-64. Again, the headers will identify the filename and type of encoding being used.

Luckily, most Usenet readers/downloaders include the capability to decode binary files automatically. Rather than "saving" a file, you mark the file and tell the reader to "decode" it. Most of the latest newsreaders will automatically figure out what kind of encoding is being used, and do the decoding transparently

Windows Decoding

In the Windows environment, all the major shareware and commercial newsreaders (Agent, WinVn, News Express, etc.) will automatically decode images. The best place to find the latest versions of the shareware programs are at the Tucows shareware software site.

If you find you must save the files first, then decode later, the best program for doing this is WinCode. Some image viewers such as VuePrint will also do decoding.

Macintosh Decoding

Fortunately, downloading and decoding files on a Macintosh is very easy. In fact, if you use NewsWatcher to browse the newsgroup, you can have the browser download and decode any posting with a single keystroke.

How to download files

If you use NewsWatcher, you can download the contents of an article by selecting it and pressing command-B or selecting "extract binaries" from the menu. If you use other software like Internews, you'll need to view the article as you normally would and then save the file to your local hard drive. Once the file is on your hard drive, you can use a uudecoder program to translate this file into a viewable format as described below.

How to decode files

To translate uuencoded files into a viewable format, you can use one of many decoders available for the Macintosh. One of the best decoders is uuUndo which provides easy drag-and-drop decoding of files. Another decoder is UULite which allows for automatic merging of split files and "super smart" decoding for more problematic files. Note that NewsWatcher and other more intelligent news readers will automatically assemble split files, so uuUndo will almost always do the trick.



Once you decode the file, you are left with an image-file on your computer. The two most widely used image types in use on the Internet are JPEG and GIF, though rarely someone will post a BMP or PIC image. To "see the pictures" on your computer, you must have a program on your computer known as an image viewer.

Windows Viewing

There are three general ways to view images in windows.

Shareware viewers and utilities can be found at Tucows.

Macintosh Viewing

There are many options available for viewing pictures on a Macintosh. As in the windows world, there are three general ways to view files:






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