WEB2PNG(1)                          Graphics                          WEB2PNG(1)

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

       web2png [-adnrtv] [directory...]

       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:

           Convert all GIF files, including those with multiple images.

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

           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.

           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.

           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.

       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.

       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.


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

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

web2png                            06/21/2019                         WEB2PNG(1)