Guide to
for Netscape Communicator
(Versions PR3 and higher)
All Contents (C) 1997 by Siegel
& Gale
Please send all comments or questions to:
Andrew Zolli
Senior Technologist
Siegel & Gale
10 Rockefeller Plaza
New York, NY 10020
azolli@siegelgale.com
1-212-707-3864
Introduction:
Thank you for your interest in PNG Live 2.0, the first in a new generation
of plug-ins written exclusively for Netscape Communicator. PNG Live 2.0
represents a significant technical achievement, shows the direction that
plug-in development will take in the future, and greatly expands the creative
possibilities for visual communication on the Web. PNG Live 2.0 was created
by Siegel & Gale, a strategic
design, communications, and interactive media firm, and is designed to
introduce a new, royalty-free, open standard in Web graphics to the larger
Web community. Siegel & Gale worked closely with Netscape Communications
engineering team to develop PNG Live 2.0. If, after reading these notes,
you have any further questions, please feel free to contact Andrew
Zolli at the address listed above.
What was installed?
In installing PNG Live 2.0, the following files were copied to your computer:
-
PNG Live 2.0 beta 5, for Windows 95/NT versions of Netscape
Communicator 4.0. This program was installed in your Netscape Communicator plugins folder
during installation.
-
PNGdemo.html, an html file that demonstrates several of the
features of PNG Live 2.0
-
Several PNG images which work with the above demonstration
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PNG Live 2.0 license text document
-
Known Issues html documentation
What Is PNG Live 2.0?
PNG Live 2.0 is a new plug-in which works with Windows 95 and Windows
NT versions of Netscape Communicator 4.0. (Preview Release 3 and higher.)
PNG Live enables the display of Portable
Network Graphics within Nescape Communicator.
Portable Network Graphics is a lossless, royalty-free image format that
is designed to replace GIF image standard. The new format is sponsored
and approved by the World Wide Web Consortium
(W3C), the Web standards-making body. The PNG format has many benefits
over the GIF format, including:
-
Smaller Files: Because the PNG format uses a better compression
method than GIF images, PNG images are on average 10-30% smaller
than GIF files. The W3C has announced findings that indicate that, by combining
PNG, Cascading Style Sheets, and HTTP1.1, the Web can become 2-8 times
faster without any further enhancements.
-
More Colors: PNG images support bit depths up to 48 bits per
pixel, or literally trillions of colors in an image.This is more
colors than the human eye can see.
-
Better Transparency: PNG images can contain many levels
of transparency, ulike GIF images, which can contain only one. This alpha-channel
transparency gives PNG many benefits over GIF, including the ability to
create and layer semi-transparent images, and the ability to create images
which are more re-usable and more portable. For example, with GIF files,
transparent images must be re-produced for each background against which
they will appear. PNG images can be placed in any such context without
requiring re-production.
-
Gamma Correction: PNG images are dynamically "corrected" so
that they appear identically on every platform. This ensures that color
images look exactly as their designer intended.
-
Searchable Metadata: PNG images can contain searchable, non-displaying
meta-content which can indicate the author, version, and history of the
image. This ability implies that one day, users will be able to search
the Web for images which meet specific criteria or have specific contents.
These are just a few of PNG's many benefits. For more details, please check
the Siegel & Gale
Codelab Web site.
PNG Live 2.0 delivers all of the benefits of the PNG standard to Netscape
Communicator 4.0 PR3. It achieves these innovations by taking advantage
of new features of the Netscape plug-in API which have just been added
to the latest version of Netscape Communicator. Of particular interest
to technical reviewers will be the following:
-
PNG Live 2.0 is the first Netscape plug-in to take advantage
of a new windowless, transparent plug-in mode within Communicator.
This mode allows PNG Live to create semi-transparent PNG images
which can be layered on top of one another in an HTML page. (See demonstration
document.) Traditionally, plug-in content is drawn into a seperate
window which is a "child window" of the parent Netscape window: this leads
to the familiar "grey box" which precedes the display ofthe plug-in content.
With windowless, transparent plug-ins, content is drawn directly into the
Netscape window, allowing the user to see the backgound of the HTML page
in which the plug-in content is embedded. This transparency enables a much
more seamless user experience: because Siegel & Gale worked closely
with the Netscape engineering team on PNG Live 2.0, the plug-in is the
first to demonstrate these features.
-
PNG Live 2.0 was created to be one of the first seamlessly downloading
and self-installing plug-ins. While this feature is not currently enabled
in Communicator PR3, it is expected in the next Preview Release of Communicator.
When this next release occurs, PNG Live 2.0 will be compressed into a JAR
file, digitally signed, and automatically and securely downloaded and installed
the first time Communicator encounters a .PNG file within an HMTL page.
Because of this automatic installation feature, the PNG Live 2.0 development
team at Siegel & Gale has reduced the size of the plug-in to under
75 kilobytes uncompressed, and under 40 kilobytes compressed! This will
ensure that users do not have to wait for more than a few seconds the first
time they encounter a PNG image.
-
PNG Live 2.0 uses an advanced dithering technique to enable
users on low resolution (256 color) monitors to see 24 bit images in the
clearest way possible. On such monitors, this dithering is invoked automatically
when PNG Live displays higher resolution images than the screen can display:
users with high resolution monitors see the higher resolution version,
users with lower resolution monitors see the lower resolution, dithered
version.
-
PNG Live 2.0 supports the use of percentage values in the WIDTH
and HEIGHT elements of the <EMBED> tag used to place images within an
HTML document. This allows images to be automatically scaled to whatever
size the Web page designer desires.
-
PNG Live 2.0 supports right-mouse click functionality, which
allows users to save a PNG image they encounter within a Web page to their
local desktop.
Creating PNG Images:
Many freeware and shareware graphics applications currently support
the PNG format.(See the PNG home page
for a complete list) However, in addition to these, several very prominent
commercial graphics and imaging tools support the creation of PNG images.
Adobe Photoshop 4.0 supports PNG images
natively on both the Macintosh and Windows platforms, and the widely used
Debabelizer image conversion tool will batch process the translation of
GIF and JPEG images into PNG images. What's more, many prominent organizations
have announced support for PNG, including Microsoft and Hewlett Packard.
Viewing PNG Images in Communicator:
To create PNG images for viewing in Communicator using PNG Live 2.0,
two things need to occur:
-
The Web server administrator or Webmaster must add the image/png MIME
type to the MIME.types configuration files.
-
The Web page author embeds a PNG image in his or her HTML document,
using the following syntax:
<EMBED SRC="NAME.PNG" WIDTH=X HEIGHT=Y>
where X and Y are the width and height of the area the designer
wishes to scale the PNG image to, in pixels: if the width and height
of the image are different from the values of X and Y, the image
will be scaled appropriately.
<EMBED SRC="NAME.PNG" WIDTH=X% HEIGHT=Y%>
where X and Y are the percentages of the larger Netscape window
to which the designer would like to scale the image. Using this
method, if the Netscape window is resized, the PNG image will be
automatically scaled to refit.
Answers to Common Questions:
We are often asked questions about PNG Live 2.0 by users, developers and
reviewers. Here are a few answers to to the questions we are asked most
frequently.
Why did Siegel & Gale create this plug-in?
Siegel & Gale created PNG Live 2.0 because the organization desired
to contribute to the quality of the user's experience on the Web. As a
leading developer, Siegel & Gale is committed to open standards, and
to giving back to the Internet community.
Are versions of PNG Live 2.0 planned for other platforms?
Yes. A port of PNG Live 2.0 is currently being worked on for the Power
Macintosh platform. It is expected later in the second quarter of 1997.
How did you create a Communicator plug-in so quickly?
Siegel & Gale and Netscape Communications are strategic partners.
We worked closely with the browser engineering team at Netscape to help
bring PNG Live 2.0 for Communicator to the public.
Where can I find more information about the new format?
There are many resources available online, including:
The PNG homepage (http://quest.jpl.nasa.gov)
This is the ultimate clearing house for information about the new standard
WebMonkey (http://www.webmonkey.com)
Wired's web browser tune up service contains an excellent article on the
PNG format.
Web Techniques December 1996 Issue
An extensive technical article appears in the December issue of this leading
Web journal
More About Siegel & Gale:
Siegel & Gale is a strategic marketing and communications firm
specializing in corporate and brand identity, language, simplification,
and interactive media. Since the early 1970s, the firm has helped
clients clarify, simplify, unify, and humanize their communications using
evocative words and striking images to project a distinctive voice in the
marketplace. Siegel & Gale has helped develop new technology solutions
for clients including American Express, Kodak, IBM, and Netscape. For more
information about Siegel & Gale's new media development efforts, visit
the Siegal & Gale homepage,
or contact Andrew Zolli at the telephone number given at the top of this
document.