Make a multi resolution .ico file from ubuntu with image magick

1. Install Image Magick in Ubuntu.

sudo apt install gcc imagemagick

2. Using your icon design create the source files.

Remember that each size should be a square and you need to make sure to have all this sizes so any device can render it correctly, the files could be .png, .jpg or .bmp.

• icon-512.png
• icon-256.png
• icon-128.png
• icon-64.png
• icon-32.png

Be careful and save all of the icons in the same directory.

3. Use Image Magick to generate the favicon.

Move in to the icons directory on your terminal.

cd /dir/to/my/icons/directory

Then run the image magick command to create the favicon based on all of the given icons.

convert icon-32.png icon-64.png icon-128.png icon-256.png icon-512.png favicon.ico

And there you are, multi resolution favicon ready to go.