File Formats and Viewers

JPEG FAQ
A faq on the JPEG (Joint Photographic Experts Group) format.

The MPEG Home Page
Moving Picture Experts Group.

Flashpix format
Flashpix, sponsored by the Digital Imaging Group, is a technology that provides a multi-resolution, tiled file format that allows images to be stored at different resolutions for different purposes, such as editing or printing, in one file. Each resolution is divided into 64 x 64 blocks, or tiles. Within a tile, pixels can be uncompressed, compressed, or single-color compressed. Flashpix has the backing of a large industry group, including Adobe, Canon, Hewlett-Packard, Kodak, IBM, Intel, and Microsoft, among others, and is rapidly gaining acceptance. In order to use the Flashpix format, you need Hewlett-Packard's OpenPix technology. The OpenPix site points to many initiatives using the OpenPix technology. OpenPix is not a file format, rather, it is a software platform for the web that allows web authors to embed images in the Flashpix format (for example) in web documents for browsers that can handle this format, while also displaying JPEG images to browsers that can't.

GridPrix
Developed at UC-Berkeley, the GridPrix file format stores the image in three different resolutions, or layers, with each layer broken down into a grid of tiles. This format allows the user to zoom in on portions of a large image and scroll to different parts of an image. The format uses server-side scripts and HTML, and so does not require special browser plug-ins or applets to view the images. At the moment, this format has not been tested in the marketplace; however, the Fine Arts Museums of San Francisco ImageBase is currently using this format for some of their images.

JTIP
JTIP (JPEG Tiled Image Pyramid) is similar to GridPrix. It offers multiple layers of higher and higher resolutions. Each layer is further divided into tiles. A user can zoom into these tiles, or request a corresponding tile at a higher resolution. (The website is in French).

PNG
PNG, or Portable Network Graphics, is an image format designed to replace the GIF format. It offers a smaller file size than GIF but does not lose any information to compression. The images in PNG format can be self-describing: in effect, information about the image can be embedded within it rather than in a separate file, which implies that these images will be located more easily by web search engines. Support for this format is not yet widespread, although the latest browsers (Netscape 4.04 and Internet Explorer 4.0b1 and above) support it (except not on Macs).

MrSID
A special viewer technology called MrSID (Multi-Resolution Seamless Image Database), developed by LizardTech, uses image compression techniques to reduce file size with little loss in image quality. MrSID allows you to zoom in or out on an area of the image that you wish to inspect. The images are stored in a .sid format. LizardTech provides free viewers to those who wish to download and manipulate .sid images, but the technology can be used to deliver a portion of the image requested as a standard JPEG, with no viewers required.