By Mikko Aarnio

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Creating Graphics

The two main image formats that Web browsers can read are GIFs and JPEGs. Each is suitable for different kind of images, so it's important to know which on to use. Once you've understand the difference between GIF and JPEG images, you'll want to determine the size and color of the graphics you're putting on your Web page.

1. When should you use GIFs?
2. When should you use JPEGs?
3. Use interlaced GIFs to speed loading
4. Animated GIFs only for special effects!

1. GIF is a good format for images with a solid flat colors and those that have sharp and distinct edges, such as text and line art.

2. JPEG is a good format for photographs and for images with subtle gradations. For photos, JPEG will look better than GIF and will compress to a smaller file size.

3. Interlaced GIFs load as blurry images at first, then progressively become more detailed. (Ordinary GIF image information is stored one pixel row at a time, starting at the top; interlaced GIF info also starts at the top, but skips several rows at a time and then goes back to fill them in.) Using these types of GIFs can make waiting for large images to load a little more bearable. It's also nicer for slower Net connection speeds, because visitors see something while they're waiting.

4. GIF images can also be used for animation; this type of graphic has come to be known as GIF89a. Basically, the GIF89a format allows developers to create small, simple animations that can be viewed with almost every browser. Because our eyes are drawn toward motion, this gimmick gives graphics extra impact. But animated GIFs can easily become annoying, because the content of the page is hard, when lots of images are blinking, flashing and rolling around.