A Complete Guide to Web Design

292 Chapter 16 – PNG Format

Platform/Browser Support

Web Design in a Nutshell, eMatter Edition

part of developers. The real foil to an all-out PNG explosion has been the lack of

browser support. Fortunately, that picture is slowly changing, and hopefully PNGs

will have their day.

Platform/Browser Support

PNG was designed to be network-friendly, so naturally it is recognized and

supported on all platforms. PNG does not enjoy universal support by browsers,

however, particularly by the Big Two. Initially, in Navigator and Internet Explorer,

PNGs could only be handled as embedded objects (placed with the<embed>tag)

and viewed with plug-ins such as PNG Live. Eventually, PNGs became supported

as inline images (placed with the<img>tag, like any other web graphic) in Navi-

gator 4.04 and IE 4.0, however, they do not support alpha channel transparency or

gamma correction without an additional plug-in.

There are a handful of lesser-known browsers that do offer PNG support in all its

glory. However, at the time of this writing, because of PNG’s lack of browser

support, they are not yet viable options for use on standard commercial web

pages. All indications show that support is growing, and PNG could become the

web standard it was designed to be. Table 16-1 indicates PNG support as of this

writing by a number of popular browsers (plus Arena, which has exceptional PNG

support, but is not in widespread use).

It should be noted that although Netscape Navigator 4.0 does not natively support

alpha-channel transparency, it does currently support binary transparency (the

same as that used for GIFs), and full alpha support is slated for version 5.0.

Table 16-1: Browser Support for PNG (as of October, 1998)

Browser

Plat-

form

View

PNGs

Progressive

Display

Gamma

Correction

Alpha-

Channel

Transparency

Netscape

Navigator 4.04

Mac X X — —

Netscape

Navigator 4.04

PC X X — With PNG

Live 2.0

plug-in

Microsoft Internet

Explorer 4.0

Mac — — — —

Microsoft Internet

Explorer 4.0

PC X X — With PNG

Live 2.0

plug-in

Microsoft Internet

Explorer 5.0b1

PC X X Not

known as

of this

writing

(Alpha-

transparency

support is

promised, but

it is not

available in

current beta)

Arena X X X X