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web2png(1)


NAME

   web2png - convert a web tree from using GIFs to using PNGs

SYNOPSIS

   web2png [-adnrtv] [directory...]

DESCRIPTION

   Web2png is a front end for gif2png(1) that automatically converts
   entire web page hierarchies from using GIFs to using PNGs. It does
   image conversion and patches IMG SRC references in web pages.

   The arguments to web2png must be directories; if none are given, the
   current directory is assumed.

   In each directory, web2png tries to convert every GIF to a PNG. It
   leaves alone GIFs that have multiple images, because these will not
   display properly in all current browsers. It also does not reconvert
   GIFs that already have corresponding PNGs (e.g. the same name except
   for the .gif file extension). The original GIFs are left in place.

   Web2png tracks successful conversions. It then looks at each HTML,
   secure HTML, HTML inclusion, PHP page, JavaScript program or Cascading
   Style Sheet under the argument directories (extensions html, shtml,
   .inc, .php, .js, .css). In these pages, it fixes each reference to each
   successful converted GIF to point at the PNG. References in relative
   HREF and BACKGROUND tags are recognized by filename and fixed (any base
   directory declared by a BASE tag will be be prepended to the relative
   URL). References that are HTTP URLs are matched against the list of
   convertible GIFs by basename; if there is such a match, the contents of
   the URL is retrieved and compared to the convertible GIF. If both
   basename and data match, the HTTP reference is fixed. If the pages are
   under RCS version control, they're checked out for modification before
   being altered; otherwise, a copy of the original of each modified web
   page is left in the same directory, with the additional extension .bak.

   The following options change the behavior of the program:

   -a
       Convert all GIF files, including those with multiple images.

   -d
       Delete originals. Removes all GIFs with corresponding PNGs, and all
       .bak files.

   -n
       Make no changes. With this option, web2png reports on what needs to
       be done (and on GIFs that have multiple images), but neither
       converts GIFs nor touches web pages.

   -r
       Reverse. Restore all HTML/SHTML/PHP pages from the .bak files
       created by a previous run (or, if the files were under version
       control, revert them). Remove PNGs with corresponding GIFs.

   -v
       Verbose. Utter more trace information about the conversion process.
       Web2png can be run on a directory that has already been partly
       converted by previous runs; it will do the minimum necessary amount
       of work. The changes it makes will be fully reversible with -r
       until you run it in -d mode. Web2png is written in Python. Python
       1.5.2 or better must be installed and accessible on your system in
       order for web2png to run.

NOTE

   Sometimes it's possible to convert transparent GIFs without altering
   the appearance of the page, by knowing from context that they will
   always place within an area of fixed and solid color. Web2png can't
   deduce when this will be, so it doesn't try; but it may be useful to
   apply gif2png with the -b option by hand.

KNOWN PROBLEMS

   The algorithm for fixing HTTP URLs is not foolproof. It could be
   confused into incorrectly patching an HTTP URL reference to a GIF into
   an invalid reference to a PNG if the GIF matches a local target GIF by
   both basename and binary content, but actually lives on another host.

   This program does not automatically convert CGIs; you'll have to do
   that by hand. Other dynamic-content methods (such as server-side
   inclusions) may also require hand-hacking.

   The program cannot tell converted from preexisting PNGs; if you have
   PNGs with the same stem name as corresponding GIFs but carrying
   different information, the -r mode will clobber them.

SEE ALSO

   gif2png(1)

AUTHORS

   Eric S. Raymond <esr@thyrsus.com>, October 1999.

   Slightly modified for Debian by Aaron Isotton <aaron@isotton.com>.



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