Common Formats

JPEG - By far one of the most common image formats. It's primarily used for photographs. It is a lossy type of format, but most people can't really see the difference. You can adjust the amount of compression when saving a jpeg image, so you do have some control over the final output quality. JPEGs are extremely popular since they compress into a small file size and retain excellent image quality.

Keep in mind that the more you compress a JPEG, the more "pixely" it will tend to look. For the best results, save your JPEGs at the "medium" or "High" setting (your imaging software should bring up this option when you go to save as a JPEG). I really can't see any image degradation in most pictures saved at the medium setting.

GIF - Another popular format, especially on the web. It's a lossless format that's ideal for graphics. GIFs can be either static or animated. If you've ever seen a graphic on a web page that was animated, you've seen one of these animated gifs. Most of the time GIFs are used for non-photographic type images. Buttons, borders, stuff like that.

BMP- This is the standard Windows image format. It's lossless and works well for pictures or graphics. It's an uncompressed file format, so it takes up lots of disk space. It's also the standard format for Windows wallpaper.

PNG (Portable Network Graphic) is a lossless image format, properly pronounced "ping". It was designed to replace the older and simpler GIF format. Like GIF you can make transparent images for buttons and icons, but it does not support animation. A PNG file can generally end up being twice the size of a JPG and three times larger than a GIF and some browsers, such as older versions of Internet Explorer and Netscape, incorrectly render them. I don't see it taking over any time soon.

ART - If you are an AOL victim, I mean "netizen", this is the reason your web graphics look bad and only your AOL friends can open the pictures you send them. By default AOL compresses image files and sends them to you as .art files. They claim that this makes pages load faster, but really it is just a way to conserve bandwidth.

TIFF- . It's a lossless format that can use file compression (called LZW compression). It won't result in as small a file as a jpeg (which is why it's not used on the web), but you do retain all image quality. When compressed, the file is usually about half the size of the original file.