Graphic file formats

There are essentially two main graphic formats in use on the web today. These are GIF (Graphic Interchange Format) and JPEG (Joint Photographic Experts Group) files. Each file format has its own benefits and limitations. GIF files are limited to a maximum of 256 colors and are best suited to images with little or no variation in shades or hues of the same color (such as clip art or vector graphics). GIF files will give you good results if you want to display flat images or illustrations that do not require high detail. While the image quality may be lower, GIFs allow you to do a few things that are currently not possible with JPEGs (ex. animations). Another unique feature of the GIF format is its ability to assign a layer of transparency within the image.

In comparison, the JPEG file format was designed with photographic imagery in mind. JPEGs are capable of up to 16 million colors and produce sharp, high resolution images (depending on your monitors display capability). JPEG files are capable of displaying subtle variations in shading and hue with remarkable quality. If image detail is important to you, consider using the JPEG format. One additional advantage that the JPEG format has over the GIF is its ability to vary compression of the file.

GIF´s	JPEG´s
Better for clipart and drawn graphics with few colours, or large blocks of colour	Better for photographs with lots of colours or fine colour detail
Can only have up to 256 colours	Can have up to 16 million colours
Images are "lossless" - they contain the same amount of information as the original (but with only 256 colours)	Images are "lossy" - they contain less information than the original
Can be animated	Cannot be animated
Can have transparent areas	Cannot have transparent areas

PNG

PNG (Portable Network Graphic) is largely considered the format of the future. PNG compression can be 8-bit, 24-bit, or 32-bit, making it the ideal format for almost any kind of graphic. However, many older browsers (I.E. 4 and Netscape 4 or older) do not support the format at all, and some newer versions still have sporadic problems. Despite some well-founded skepticism, the future still looks somewhat bright for the license free PNG.