Website Usability Guidelines

GIF vs. JPEG

Graphic Interchange Format (GIF) and Joint Photographic Experts Group (JPEG) are two formats commonly used for web graphics. Both JPEG and GIF images are cross-platform, which means they are viewable by just about any type of computer. This is a must due to the diversity of computers available on the market today.

Both formats use compression techniques to reduce file size. Compression is especially important regarding the internet since it allows files to be transferred more quickly, thus reducing download time.

Although both formats are appropriate for web design, it is important to understand how the two differ in order to determine the best format for a particular image.

GIFs deliver a no loss in compression, meaning that the image does not lose quality in the process. JPEGs, on the other hand, are a loss in compression, meaning that information from the image is removed, thus causing some loss in quality. GIFs and JPEGs also differ in the number of colors they can display. GIF images are limited to 256 colors (8-bit), whereas JPEGs can utilize up to 16.7 million colors (24-bit). This is why JPEGs are best used for images where there are subtle transitions between colors.

A GIF is the preferred format for images with large areas of solid, flat color. An added feature of the GIF format is the ability to allow the one color to be transparent. This feature gives web developers the option of making the background of irregularly-shaped images 'invisible. This is accomplished by assigning the particular background color to be transparent. GIFs also offer the capability of browser-safe animation since they require no plug-ins and are supported by major browsers.