png2ico(1)                                             png2ico(1)



NAME
       png2ico  -  convert  .PNG  file(s)  to  Windows  .ICO icon
       resource


SYNOPSIS
       png2ico   outfile.ico   [--colors    <num>]    infile1.png
       [infile2.png ...]


DESCRIPTION
       png2ico  takes the input files and stores them in the out-
       put file as a Windows icon  resource.  Usually  the  input
       files would all represent the same image in different res-
       olutions (common resolutions are 16x16, 32x32 and  64x64).
       A  program  reading  the icon resource will pick the image
       closest to its desired resolution and will then  scale  it
       if necessary.

       Using the parameter --colors you can specify the number of
       colors to use for the images that follow --colors  on  the
       command  line.  Allowed values are 2, 16 and 256. If omit-
       ted, 256 colors will be used. --colors  can  be  specified
       multiple  times  to store images with different numbers of
       colors in the same icon file. If the source image has more
       than  the specified number of colors, color reduction will
       be performed.


FAVICON.ICO
       Most graphical  browsers  today  support  the  favicon.ico
       file.  When  a user bookmarks a web page, the browser will
       automatically check if it finds a favicon.ico file on  the
       web  server and display it in the bookmarks menu.  Depend-
       ing on the browser and configuration the  favicon.ico  may
       also appear in other places.

       To  create  a  favicon.ico simply create a 16x16 .PNG file
       and convert it to an icon resource with png2ico.  You  may
       of  course  add  other  alternative  resolutions  but most
       browsers only use a 16x16 image. Keep in mind that  for  a
       user with a slow modem a favicon.ico may increase the page
       loading time by a few seconds if it is too large, so don't
       overdo  it. Adding a 32x32 alternative should be enough to
       make sure the image will look good even in  contexts  with
       larger  icons. Adding even more and larger alternatives is
       unnecessary bloat.  Try to keep the number of colors below
       16 and create a 16-color icon using the --colors 16 switch
       of png2ico (or even create a b/w icon using the --colors 2
       switch).  This  will  result  in a smaller file that loads
       faster.

       Don't forget that the favicon.ico may be composed  against
       backgrounds  of  different colors so you should use trans-
       parency rather than a solid  background  if  you  want  to
       avoid that your icon appears inside a box.

       To  add  your  new favicon.ico to a web page put it on the
       server into the same directory as the web  page.  That  is
       the  1st place a browser will look.  If it doesn't find an
       icon there, it checks the top-level directory of  the  web
       server,  so  by  putting  it  there you can have a default
       favicon for all the pages in your  domain.   Depending  on
       browser  and  configuration, the favicon.ico is not always
       rendered, even if it is in one  of  the  above  locations,
       unless  the  web page explicitly declares its presence. To
       declare that your web page has an icon, you add  the  fol-
       lowing 2 lines into the <head> section of your page:

              <link         rel="icon"         href="favicon.ico"
              type="image/x-icon">

              <link    rel="shortcut icon"     href="favicon.ico"
              type="image/x-icon">


EXAMPLES
       To  create  a  favicon.ico  from  2 logo files (the 1st in
       16x16 resolution and the  2nd  in  32x32  resolution)  you
       could use the following command:

              png2ico favicon.ico logo16x16.png logo32x32.png


BUGS
       The  color  reduction  algorithm  used  by png2ico is very
       slow. If you have an input file with several thousand col-
       ors (very unlikely), it may take several seconds to create
       the icon. If possible, reduce the number of colors in your
       .PNG files before passing them to png2ico.

       The handling of the transparency mask is very inconsistent
       in programs.  The same program will sometimes interpret it
       differently  depending  on context.  png2ico takes precau-
       tions to make sure that the  icon  will  always  look  the
       same.  For  doing this, png2ico uses one palette entry for
       black  (0,0,0)   and   one   palette   entry   for   white
       (255,255,255),  even  if  the  icon does not have a single
       black or white pixel. This means that 2-color  icons  will
       always  be  black  and  white. In 16/256-color icons, only
       14/254 colors can be chosen freely.


AUTHOR
       Matthias S. Benkmann <matthias@winterdrache.de>.

       png2ico lives at http://www.winterdrache.de/freeware


SEE ALSO
       convert(1), gimp(1)



                           1 June 2002                 png2ico(1)
