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April 15, 1998
Technology Companies Push
For Standards on Web ImagesBy PETER WAYNER
everal major technology companies took steps this week to unify the disparate worlds of the World Wide Web and print media by announcing plans to support a new standard for distributing "vector-based" artistic content. They hope that digital designers will be able to create sophisticated artwork that looks good when displayed on a computer screen and also when printed in much higher resolution upon paper.
Adobe Systems led a group, including IBM, Sun and Netscape, that submitted plans for what it calls a Precision Graphics Markup Language, or PGML. In a separate but related announcement, Macromedia announced new plans for welcoming collaboration on its vector-based animation technology known as Flash, as well as support for the format from Microsoft, IBM, Sun and Real Networks.
Illustration: Christine M. Thompson / CyberTimes
Today, most artistic content on the World Wide Web and other computer media is distributed as bit-mapped graphics in file formats with names like GIF (for Graphics Interchange Format) or JPEG (for Joint Photographic Experts Group). These formats describe the color of each individual dot on the screen. A basic computer monitor shows a grid of pixels that is 640 pixels wide and 480 pixels high; regardless of its dimensions, however, it can only display a resolution of 72 dots per inch.
Vector-based graphics use a higher-level description that contains line-by-line information about how the information is displayed upon the screen. A horizontal line, for instance, would be represented with the starting point, the ending point, the width of the line and the color. The local computer is responsible for converting this information into the colors of the individual pixels displayed on the screen in a process known as either "rendering" or "raster image processing."
These vector formats are popular with designers because they provide comprehensive descriptions of art that can be customized to fit the quality of the local display device. If the art is sent to a laser printer, for instance, then the lines can be drawn at higher resolutions that use all of the 600 dots per inch that are available. If the art is sent to a lower-resolution display like a computer monitor or a television, then the software can optimize it for this level of detail.
Halle Winkler, a San Francisco-based designer said: "HTML text is really a catastrophe. It's perfect for information delivery, but for actual design it's terrible for designers." She pointed out that vector-based formats take up less space and give the designers the power to specify exactly where letters and lines will appear. HTML text, for instance, is cut by the local browser into lines that fit the local screen
Richard Cohn, a senior computer scientist at Adobe who helped develop the PGML standard, points out that printing is just as important as displaying the information on the screen. He said, "Everyone's gone off and printed nice looking Web pages and they look lousy when they're printed." The PGML system would solve this problem by providing higher level descriptions of the art work that could also be drawn at higher resolution without jagged edges for the printers.
The technology is also important for companies like Microsoft's WebTV, which makes a device that displays Web information on a television screen using a sophisticated rendering algorithm that compensates for the television's poor resolution. A device-independent format like PGML would allow them to optimize the image for their needs. Currently, they devote a large amount of time and computational power to resizing images designed for a standard computer so they'll look good on the lower-resolution television.
The PGML standard is currently just a proposal that is sitting with the W3C, an industry-wide, standards-making body that tries to anticipate and solve some of the technical problems facing users of the World Wide Web. The body will probably create a working group that will analyze the proposal and move toward creating a standard.
In related news, Macromedia released the technical specifications for its Flash file format used to create animated vector graphics. Previously, only Macromedia tools could be used to produce the Flash files, a fairly common form for presenting animated artwork and music on the Web. Norman Meyrowitz, the chief technical officer at Macromedia, said the company was trying to encourage more people to build products that would use the format in the hope of making it a lingua franca for the Web.
The solution could be a double-edged sword for Macromedia. If the format becomes more popular, it could encourage the development of tools that compete with Macromedia's own offerings. Winkler, for instance, produces Flash files often, but confesses, "I prefer Adobe Illustrator to Macromedia Feehand and I would like to have that option. I'm hoping that Adobe will incorporate Flash formats into Illustrator." Still, the owner of the dominant technology often maintains the lion's share of the market. Adobe's PostScript format for printing vector images has been cloned by many companies, but Adobe still produces the leading products for using it.
The move by both companies opens up the arena for more competition. Macromedia's solution has the advantage of being currently available and optimized for the Web. The company is distributing both plug-in software for the major browsers as well as Java-based code that makes it possible to display Flash files on screens without plug-ins. The company is also developing Web-based content and producing Web-only animated cartoons like South Park or Peanuts. All can be viewed on the company's Web site.
By contrast, PGML is only a proposal at this point. Adobe clearly hopes to use its experience with its PostScript language to make it easy for people to produce PGML artwork. All of the major online illustration tools produce output in PostScript format, so it should be fairly simple to make the modifications to have them produce PGML documents. Adobe also hopes to use its experience producing fast renderers for PostScript to creating fast renderers for PGML documents. The PGML specification mentions animation, but it does not begin to offer the same level of detail or range of features as the Flash technology which is already in its third generation.
PGML also has the advantage of integrating itself with some of the evolving Web standards. PGML files are built using an XML (eXtensible Markup Language) grammar, which means that they will fit into the framework dictated by the XML specifications. This allows other XML tools to manipulate PGML graphics and should make it possible, for instance, for popular search engines to peer inside PGML documents and extract some of the key words. Currently, bit-mapped graphics can't be understood by these engines.
The downside is that a PGML file can be quite large. It uses tags like "<rectangle x="100" y="100" width="100" height="100" >" to represent a rectangle. Flash might represent this in a block of bytes about one-tenth the size because it uses a binary format. Eventually, XML-based compression tools could also be used to make PGML files smaller, but the current standard does not include any indication that there will ever be compression aimed solely at PGML.
Ted Simonides, the director of marketing of Web-related products at Adobe, said that he imagined that the W3C standards body would eventually lead to a merging of the PGML and Flash standards. "We see them as coming at the same thing from two differnet angles," he said. "That's the reason for us to take it to the W3C. It's not going to be good for any of us. We expect that this is something we'll be working through together."
In either case, Meyrowitz hopes that vector-based formats like Flash will increase the quality of Web-based productions. "Boy, this shows the Web could really be exciting and compelling," he said. "It already has the immediacy that television doesn't have, but right now it looks like a brochure. Imagine if you had the immediacy of the Web with the production values of television?"
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Peter Wayner at pwayner@nytimes.com welcomes your comments and suggestions.
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