4.1.2 "What Is Flash?"

Macromedia Flash is the leading tool for designing and delivering low-bandwidth animations, presentations, and Web sites. It offers scripting capabilities and server-side connectivity for creating engaging applications, web interfaces, and training courses.

 
Low-Bandwidth

Flash is special in that it can display dynamic, animated content through your browser in less space than it would take to display the equivalent flat, motionless graphics. Take the header of this page as an example.

What we see in this example is that the animated Flash header was five times smaller than the equivalent flat jpg image.

Although the non-Flash version of the navigation bar was nearly half the size of the Flash navigation bar, it lacked sound, and it created 11 times more hits on the server. Each hit puts additional load on the server and increases the amount of time required to load the page (due to network latency.) The overhead for handling each hit would nearly wipe out the bandwidth advantage of the non-Flash version.

[If you'd like to see the Flash version of this page, follow the link at the bottom of the page.]

So Flash gives you more for less, but how does it do this?

 
"Raster" vs. "Vector"

Flash is centered around what are called "vector" graphics. Traditional graphic file formats are "raster" graphics — they describe every pixel (dot) in the image. This is the technology behind the most common graphic file formats on the web — .jpg and .gif. When animations using these formats are produced the size of the file is proportional to the number of "frames" in the animation.

The vector graphics that Flash uses describe shapes mathmatically. This can be a confusing concept. The best analogy we've heard is the cake analogy. If you were a raster graphic and wanted to send a cake to someone you would bake the cake, package it and mail it. If you were a vector graphic, you would send the person the recipe and a few key ingredients he or she may not have on hand, leaving the baking up to the recipient. It may not be the most generous way to give someone a cake, but if 10 people dropped in unexpectedly, the person could just bake a bigger cake.

The benefit of vector graphics is that they can print at resolutions different from those shown on-screen. This avoids the problem of "jaggies" when printing web pages. To see an example that uses Flash in this way, click here.

The possible disadvantage of vector graphics is that they can be processor-intensive (because you have to "bake the cake" yourself). This is not usually a problem, but in some cases it does become an issue. For more information, click here.

 
Other Resources

More information about Flash can be found on the Macromedia web site.

To learn more about Slicksurface's experience with Flash, click here.