How can I control the content of a favicon.ico file?

Question

I want to edit each single size icon in the file manually so that I get exactly what I want.

Is there a tool that will let me have a merged 16x16, 32x32, 48x48 and 64x64 icon that will let me control the content (the exact pixels) of each size?

I've used some favicon generators and uploaded a 48x48 image but my image does not do well when downsized automatically, it needs human intervention from a designer (me).

Answer 1

There are various applications you can download or there are web based editors such as http://www.xiconeditor.com

Answer 2

You can use free, command line tools. Icoutils:

# On Ubuntu
sudo apt-get install icoutils
icotool -c -o favicon.ico 16x16.png 32x32.png 48x48.png 64x64.png

ImageMagick:

# On Ubuntu
sudo apt-get install imagemagick
convert 16x16.png 32x32.png 48x48.png 64x64.png favicon.ico
# If you use IM version >= 6.8.8-3, you can even resize the original picture
# and create favicon.ico at once:
convert input.png -define icon:auto-resize=64,48,32,16 favicon.ico

As an aside, you mention all supported sizes, up to 64x64. Although this size is documented, Microsoft recommends only 16x16, 32x32 and 48x48. There are reasons to think that the 64x64 picture is never used (granted, that was tested on Windows 8.1 only).

Keep in mind that you need a lot of pictures in order to support all platforms: iOS, Android, etc.