GIF2PNG(1) Graphics GIF2PNG(1)
NAME
gif2png - convert GIFs to PNGs
SYNOPSIS
gif2png [-bdfmvwO] [file.[gif]...]
DESCRIPTION
The gif2png program converts files in the obsolescent Graphic
Interchange Format (GIF) to Portable Network Graphics (PNG) format, an
open W3C standard.
Normally gif2png converts each file named on the command line, leaving
the original in place. If a name does not have a .gif extension, the
unmodified name will be tried first, followed by the name with .gif
appended. For each file named foo.gif, a foo.png will be created.
When a multi-image GIF file named foo.gif is converted, gif2png creates
multiple PNG files, each containing one frame; their names will be
foo.png, foo.p01, foo.p02 etc.
If no source files are specified and stdin is a terminal, gif2png lists
a usage summary and version information, then exits.
If no source files are specified, and stdin is a device or pipe, stdin
is converted to noname.png. (The program can't be a normal
stdin-to-stdout filter because of the possibility that the input GIF
might have multiple images).
However, if filter mode is forced (with -f) stdin will be converted to
stdout, with gif2png returning an error code if the GIF is multi-image.
All graphics data (pixels, RGB color tables) will be converted without
loss of information. Transparency is also preserved. The GIF
aspect-ratio field, offset fireld, and extensions are dropped.
The program automatically detects images in which all colors are gray
(equal R, G, and B values) and converts such images to PNG grayscale.
Other images are converted to use the PNG palette type. Duplicate color
entries are silently preserved. Interlacing is removed.
The action of the program can be modified with the following
command-line switches:
-b {#}RRGGBB
Background. Replace transparent pixels with given RGB value, six
hexadecimal digits interpreted as two hexits each of red, green,
and blue value. The value may optionally be led with a #,
HTML-style.
-d
Delete source GIF files after successful conversion.
-f
Filter mode. Convert GIF on stdin to PNG on stdout, return error if
the GIF is multi-image.
-m
Preserve file modification time. The PNG output gets the mod time
of the input file, not the time it was converted.
-v
Verbose mode; show summary line, -vv enables conversion-statistics
and debugging messages.
-w
Web-probe switch; list GIFs that do not have multiple images to
stdout. GIFs that fail this filter cause error messages to stderr.
-O
Use zlib compression level 9 (best compression) instead of the
default level.
LIMITATIONS
Naively converting all your GIFs at one go with gif2png is not likely
to give you the results you want. Animated GIFs cannot be translated to
PNG, which is a single-image format.
The web-probe switch is intended to be used with scripts for converting
web sites. In versions of this tool up to 2.5.2 it filtered out GIFs
with transparency as well as GIFs with animations, but support for PNG
transparency has been universal in browsers since about 2006.
RETURN VALUES
Normally returns 0 for successful comp[letion. A return of 1 is a
recoverable error (batch processing continues).
STANDARDS AND SPECIFICATIONS
Copies of the GIF89 specification are widely available on the Web;
search for "GRAPHICS INTERCHANGE FORMAT". The Graphics Interchange
Format(c) is the Copyright property of CompuServe Incorporated. GIF(sm)
is a Service Mark property of CompuServe Incorporated. The GIF format
was formerly covered by a blocking patent on LZW compression, but it
expired in June 2003.
The PNG home site at has very complete
information on the PNG standard, PNG libraries, and PNG tools.
SEE ALSO
web2png(1)
AUTHORS
Code by Alexander Lehmann , 1995.
Auto-interlace conversion and tRNS optimization by Greg Roelofs
, 1999. Man page, -O, -w, and production packaging by
Eric S. Raymond , 1999. -m option by Steve Ward, 2012.
gif2png 07/12/2024 GIF2PNG(1)