1. Tutorial Image editing:
U can create the image as .png with the Gimp Software, here the tutorial:
Drupal interface did not like the.ico format directly saved from GImp, did not appear so I have saved a .png in Gimp and converted …
2. Post Image converting:
Post about converting .png to .ico with the Terminal on Linux:
Designers: Dont Panic !
If the lines of code make bleed your eyes, but you still want to work with Open Source Software … work with Linux developer or
get Ubuntu Studio optimized for Graphic Design, then all the tools are already include into your Operative System.
In the case you have all the tools:
you ´ll need to go into the directory where you have the png
$ cd Documents/design/logo/
and use just the last line from the article
$ icotool -o favicon.ico -c favicon.png