It seems as if everything is going digital these days. Digital audio, digital graphics, digital photography, digital cellular phones, even digital video. What's the big deal? For that matter, what is digital?

Anything that is in digital form is in bi nary code, a collection of 1s and 0s that computer software can understand. Among the reasons digital is so popular is that data and images can be manipulated easily in digital form. For example, it used to be that most audio editing was done on reel-to-reel magnetic tapes, and the editor physically marked the edit points and then cut and spliced the tape. Now it's done with just a few mouse clicks. Digital is also hot because multiple copies can be made without degradation. Copy number 32 is identical to copy number two. In analog media (audio or video), every generation (copy) from the original suffers in quality.

Going digital is also a big time-saver. Slides and overheads created "the old way" were first typeset, then sent to an optical camera. The quickest you could turn a slide around would be several days. Now, with most slides being created by computers, you can either modem the files to a lab or take a disk over and have your slides back in half a day. And, with data projection you can make changes right up until show time.

When you save time, you save money. A video edit session that would have taken 20 hours can be edited in five hours or less. Instead of having to assemble the video in chronological sequence, cueing the tapes back and forth to find your start and end times, digital video can be accessed almost instantly and can be assembled in any sequence. Consequently, a video production that might have cost you $20,000 several years ago, could cost you as little as $7,000 today.

Digital has become affordable. Some of the top-of-the-line digital audio editing systems cost $100,000. The original computer graphics systems cost that much as well. Now you can get excellent systems for a tenth of that cost. The original digital video cameras were very expensive, upwards of $30,000. Now you can buy cameras with better capability for under $1,000.

Not only is the hardware much less expensive (and the corresponding rental of that hardware), it's also easier to use. Ten years ago it would take a computer graphics operator several months of eight-hour days to become proficient on a system. Now one can become productive in a few days.

One of the most confusing aspects of working in digital graphics for most planners is understanding the choice of file formats. You can normally tell which file format is used by the three-letter file-name extension. The expected use of the image will dictate which file format is best. There usually is a trade-off between quality and compression. The most popular formats:

* TIFF (Tagged Image File Format) uses the .tiff file extension. TIFF is generally used for original images, providing compression savings of about 20 percent over uncompressed images. TIFF is used to store bit-mapped files on both PCs and Macintosh computers.

* JPEG (Joint Photographic Experts Group) uses the .jpeg file extension. This format is considered best for photographs, rendered graphics (such as paintings), and continuous-tone images. It has high compression ratios (up to 100 to 1), but with JPEG some of the data is lost each time the file is compressed, making images less detailed with each compression. To avoid such losses, an image might be created in TIFF and then converted to JPEG as the last step.

* GIF (Graphics Interchange Format) uses the .gif file extension and is considered best for line art, logos, inline images, and screen captures--images that have mostly solid colors, with little or no shading, and that contain few colors. You can edit and re-edit GIF files without image degradation. GIF's enhanced format supports interlacing and transparency options, making it a good choice for Web page graphics.

Is digital the answer to everything? No, but it's a tool that all planners will be using more and more in their everyday work.