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Graphics Interchange Format
(.GIF files)
Joint Photographic Experts Group
(.JPEG files)
Portable Network Graphic
(.PNG files)
Compression: Compresses by scanning horizontally across a row of pixels and finding solid areas of color. Indexes the pixels based on the 256 color palette in the file. No image information is lost. Note: some information may be lost in the conversion process from RGB to GIF format. Compression: Some image data is discarded when it is compressed, reducing the quality of the final file. The compresion algorithms handle sharp edges and abrupt changes poorly. Does not use palettes for referencing color information. In General, a JPEG will compress a photographic image 2-3 times smaller than GIF. You can choose how much to compress a JPEG file, but since it is a lossy format, the smaller you compress the file, the more color information will be lost. Compression: Compresses across rows and columns of pixels, often yielding better compression than GIF, which only scans rows. The compression is 'lossless', you do not lose color information as you compress the file smaller. Typically compresses images 5-25% better than GIF.
Best for: Images with repetitive areas of solid color, line drawings, screenshots, sharp images. Ideal for cartoon-like graphics, logos, graphics with transparent areas, and animations. Excels at condensing graphical images with areas of flat color. Best for: Scanned photographs, images using textures, images with gradient color transitions or any images that require more than 256 colors. It is generally best to let JPEGs handle photographic material and to leave the graphics to GIF. Best for: Creating complex live transparency, high-color graphics, and better compressed low-color graphics.
Colors Supported: Contains only 256 colors (8-bit). Can contain a transparent area and multiple frames for animation. Colors Supported: Supports millions of colors (24-bit). Colors Supported: Can support up to 8-bit palette indexed color, 16-bit grayscale images, 48-bit truecolor. Can contain transparency or an alpha channel, and can be progressive.
Downloads using: Interlacing, which uses the same technique for downloading as JPEG's progressive encoding. An interlaced GIF displays images in two passes of alternating lines instead of loading them one line at a time. The viewer begins to see the outline of the image sooner with interlacing. Downloads using: Can download using progressive encoding: This technique downloads a rough whole image and gradually increases the image's clarity, instead of downloading from the top of the image and moving downward as is done normally. Requires more processing power to display. If the browser does not support progressive encoding, the images loads from top to bottom. Downloads using: A more sophisticated interlacing technique than GIF and starts displaying the image in 1/8th the time.
Browser Support: First graphic file type to be displayed by the early web browsers. The only graphic file formate that is universally supported by all graphical browsers, regardless of version. Most popular and versatile format for distributing color image on the Web. Browser Support: Fully supported for use as inline images in version 2.0 and higher of Netscape Navigator and Internet Explorer, as well as in most other current browsers. Browser Support: The most versatile of the Web graphic formats, however not all Web browsers can currently take full advantage of PNG characteristics without using plug-ins.
Other Issues: Any image can be saved as a GIF and the files are completely platform independent. The company holding the patent on the LZW compression model used in GIFS, has started to enforce the patent and charge software companies fees for including GIF support. This action led to the development of PNG. Other Issues: Need to be decompressed before they can be displayed; therefore, it takes a browser longer to decode and assemble a JPEG than a GIF of the same file size. Other Issues: Designed to be network-friendly, so it is recognized and supported on all platforms. Supports both indexed and truecolor image types, so there's no bitmapped graphic it can't handle. For Web purposes where every byte counts, photographic and continuous tone images are still best saved as JPEGs. The better compression engine results in a smaller file size than GIF for the same image.
Last Modified:September 21, 2000