Beyond GIF and JPEG: New Digital Image Technologies
Roy Tennant -- Library Journal, 2/15/1999
Whenever you surf the web and an image pops up on your screen, it can presently be one of only two types: GIF or JPEG. The GIF format, created by CompuServe in 1987, is limited to 256 colors or shades. JPEG images, developed by the Joint Photographic Experts Group in 1992, can store millions of colors, but large, high-resolution images can get too large to serve over the Internet to modem users.
To view these images, all you require is a computer connected to the Internet and a web browser such as Netscape or Internet Explorer. To create them, however, you also need some kind of image editing program such as Paintshop Pro (for the PC only) or Adobe Photoshop (for both PC and Mac). These programs allow you to create, edit, or manipulate images and save them in different file formats. (GIF and JPEG are the main ones, however, to view with a web browser.)
But technology has now marched ahead. While the Fine Arts Museums of San Francisco (FAMSF) use some GIF and JPEG images for now, they are well along in a process to move their 70,000 online images into an entirely different format that allows users to zoom in so close they can almost see the brush strokes. The Library of Congress (LC) provides similar options for those viewing its online collection of panoramic maps. Although neither technology requires anything special of the client (all processing is performed on the server, and JPEG images are served to the user), each differs completely from the other.
|
LINK LIST | |
| Fine Arts Museums of San Francisco ImageBase http://www.thinker.org/imagebase/ | |
| Flashpix http://www.digitalimaging.org/ | |
| Digital Imaging for Libraries and Archives http://www.library.cornell.edu/ preservation/dila.htm | |
| Grand Prix http://now.cs.berkeley.edu/Td/ GrandPix/ | |
| JTIP http://www.avelem.fr/ | |
| Library of Congress Panoramic Maps Collection http://memory.loc.gov/ammem/pmhtml/ | |
| MrSID http://www.lizardtech.com/products/mrsid/ | |
| OpenPix http://image.hp.com/ | |
| PGN http://www.cdrom.com/pub/png/ | |
| "The Promise of the FlashPix Image File Format" http://www.rlg.org/preserv/diginews/ diginews22.html#FlashPix |
These are but two examples of emerging digital image formats and technologies that promise to revolutionize how we use and interact with images on the Internet. For example, while presently it's impractical to make available a high-resolution version of a large image (due to the time it would take to download the file), these new image formats allow users to specify and retrieve only a segment of the image. Other capabilities of various technologies all promise, at the very least, to overcome the bandwidth challenges of serving images online.
GridPix
The image file format used by the FAMSF was developed by the University of California, Berkeley. It stores the image in three different resolutions or "layers," with each layer broken up into a grid of tiles. As the user requests a higher resolution or pans around the image, only the appropriate tiles are sent to the web browser. No browser plug-ins are required to view these images. The FAMSF appear to be the only institutions using this format, which has so far been a research project untested in the marketplace.
MrSID
LC uses a proprietary solution from LizardTech, Inc. (a spinoff from Los Alamos National Laboratory) called MrSID (an acronym for Multi-resolution Seamless Image Database). MrSID uses advanced image compression techniques to reduce file size with relatively little loss in image quality. While LizardTech provides free viewers to anyone who wishes to download and manipulate MrSID images, LC and others use LizardTech technology to deliver the portion of the image requested as a standard JPEG image, with no special viewer required.
Flashpix and JTIP
The digital image format Flashpix has been developed and promoted by industry heavyweights in the Digital Imaging Group (DIG), including Adobe, Canon, Kodak, Hewlett Packard (HP), IBM, Intel, and Microsoft. Flashpix stores multiple resolutions of an image in one file. Each resolution is then also tiled into 64x64 pixel squares. Thus, the system can serve only the required segment at the required resolution rather than the entire file.Unlike the similar GridPix, Flashpix has the backing of a broad-based industry group and is rapidly gaining acceptance. To view and use Flashpix images, you currently need to download a plug-in or use HP's OpenPix technology (see below).
Also similar to GridPix, JPEG Tiled Image Pyramid (JTIP), invented by a French company but not yet in widespread use, offers multiple layers of higher and higher resolutions. Each layer is chopped up into blocks or tiles. Therefore, a user can pan and zoom by requesting the next tile, or a corresponding tile at a higher resolution. (The web link is in French.)
OpenPix and PNG
Although it sounds like one, OpenPix is not an image file format. Rather, it is a software platform for the web developed by HP that allows web authors to embed richer images such as Flashpix in their web documents for those browsers that can handle them, while serving up plain JPEG images to those that can't. The OpenPix web site points to a number of implementers of this technology, including Encyclopedia Britannica.
Portable Network Graphics (PNG) is an image format designed to replace GIF. It offers smaller file sizes than GIF but doesn't lose any image information due to compression. Information about the image can also be embedded within it rather than in a separate file. Since the images can then be self-describing, if image creators use this feature, web users will find it much easier to locate images using web search engines.
This format is presently the only one beyond GIF and JPEG supported at all by the latest web browsers (Netscape versions 4.04 and above; Internet Explorer version 4.0b1 and above; not on Macs). But support for all the capabilities of this format is still somewhat spotty.
And the winner is...
So which of these formats will unseat GIF and JPEG? It's still too early to make a reliable prediction, but Flashpix has the broadest industry support, and PNG has the backing of those who prefer technologies built on open standards. GridPix remains a research project, and JTIP is not yet in wide use. Still, don't count MrSID completely out of the game. It delivers some remarkable capabilities while keeping the complexity on the server (users may never know that they're interacting with a different kind of image). My best guess is that PNG and Flashpix both will gain wide use. PNG images probably will be used to replace GIF images and perhaps some JPEGs, while Flashpix will be used to deliver very large, high-resolution images to provide the sharpest detail possible via network delivery.
Roy Tennant (
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