Q Every Saturday I receive a 3-page fax through my RapidCommVoice program. I then need to resend this fax to a friend in Adelaide. However, he doesn't have RapidCommVoice or any other fax program, so his PC cannot read .hfx files. Accordingly, I have to save the .hfx file as a compressed .tif file and e-mail it to him. Problem is, the e-mail takes forever to send and, of course, to receive at his end.

A There are several issues to consider when it comes to sending image files to other people. These include file size and quality, and how easy is it for the recipient of the file to read it.

In graphic art and desktop publishing TIFF ù or Tagged Image File Format (sometimes written "TIF" after the 3-letter DOS extension) ù is commonly used. TIFF is widely supported and can be read by applications such as MS Word. Unlike a lot of other graphics file formats, the basic form of TIFF does not include any compression. The result is large files. There is a version of TIFF that uses LZW compression but not all programs that support TIFF support the compressed version. It is not a good idea to send compressed TIFF files unless you are sure the person receiving the file can read them. For your purpose, TIFF is not really the best file type to use.

Two file formats that were created specifically for being sent over networks are GIF and JPEG. Both have the advantage of being able to be read by most Internet browsers, and many e-mail packages allow you to view the image directly.

GIF (or Graphical Interchange Format) was developed by CompuServe and has good compression but only supports 256 colours. There are two versions, GIF87 and GIF89a. Both formats are widely supported, with GIF89a only really adding animation.

JPEG files, developed by the Joint Photographic Experts Group, use fractal compression that can produce incredibly small files compared to other compression techniques. Unfortunately, this type of compression also means some loss of information. Most programs let you choose how much information you are prepared to lose when you save an image in JPEG format. For most images the loss of information is not even noticeable. The JPEG format is not suitable for the sort of high-quality images used for glossy magazines, but would work well for the black and white fax images you are sending.

Your fax program may not support GIF or JPEG files. If you need to convert an image file you will find that most graphics programs support several different file formats but not always the one that you want. ImageCommander (www.jasc.com) supports 30 file types and offers basic image-editing.

You can also compress a file using a compression utility. These tend to achieve better compression ratios than most graphics files except JPEGs. It also means you can group several files into one, which is more convenient to send. The most widely used compression format ù which should be familiar to almost all PC World readers ù is the Zip file standard developed by PKWare. Shareware and freeware Windows and command line Zip utilities are downloadable from www.pkware.com and www.winzip.com. Included are utilities that allow you to create self-extracting Zip files so that the recipient can unzip the files without needing a copy of the compression utility.