“Images used for the Web have not kept pace with other aspects
of Web technology, but improvements are emerging, in the form of
PNG files and vector graphics formats.”
“In 1995, a controversy erupted over the use of GIFs when Unisys
Corp., which owns the LZW compression the format used, and
CompuServe, which licensed it, decided programs implementing GIF
would have to pay royalties. That controversy sparked the
development of a new, improved format: PNG (Portable Network
Graphics). Created by an informal Internet working group and
adopted by the W3C in 1996, PNG was designed to meet or exceed
GIF’s capabilities, to be easy to implement, and to be completely
portable. It is royalty-free with full source code publicly
available. The specification was updated to Version 1.1 in December
1998, bringing improvements for gamma and color correction as well
as clarification of key features.”
“PNG supports indexed color, true 48-bit color images, and
16-bit gray-scale images, as well as a fairly advanced
two-dimensional interlacing method called Adam7, which displays an
image progressively in seven stages and is much more powerful than
the four-stage method used with interlaced GIFs. As a result,
progressive PNGs appear to display faster and become intelligible
sooner than interlaced GIFs.”