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
       output file as a  Windows  icon  resource.  Usually  the
       input  files  would all represent the same image in dif-
       ferent resolutions (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
       omitted, 256 colors will be used. --colors can be speci-
       fied  multiple times to store images with different num-
       bers 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.
       Depending on the browser  and  configuration  the  favi-
       con.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 num-
       ber  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 transparency 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 following 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
       colors (very unlikely), it may take several  seconds  to
       create  the icon. If possible, reduce the number of col-
       ors in your .PNG files before passing them to png2ico.

       The handling of the transparency mask is very  inconsis-
       tent  in  programs.   The  same  program  will sometimes
       interpret it differently depending on context.   png2ico
       takes precautions 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)
