The selection of PNG-supporting image viewers for VMS (or OpenVMS nowadays)
is rather limited; indeed, I am aware of only two viewers, both ports of
popular Unix/X viewers:
- ImageMagick display
Version 4.2.0, John Cristy. Conversion
capabilities (mostly via accompanying convert utility); full gamma
support; reported to include chromaticity support; partial MNG support. There
is also a 32-bit Windows port, but it requires a third-party X server to run.
Version 3.10a, John Bradley. Conversion capabilities, including
interlacing support but without the ability to write transparent PNGs; full
gamma support; preserves text information. XV is widely considered to be the
preeminent image viewer for the X Window System.
The only major drawback is that it was last released in December 1994, five
days before the CompuServe/Unisys GIF announcement that began the PNG saga,
and therefore does not include PNG support in the default distribution.
Fortunately, it is available as C source code, and the home page includes not
only the PNG patch but also several others, so it can be recompiled and
tweaked at will. An upcoming patch will allow an image-background color to
be set, similar to the -bgcolor option in the demo viewers in
Chapter 13, "Reading PNG Images" and Chapter 14, "Reading PNG Images Progressively".