bionic (1) web2png.1.gz

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>.