Make a multi-resolution favicon.ico from a source image, using ImageMagick

mkfavicon.sh

#!/bin/bash

# from
# http://bergamini.org/computers/creating-favicon.ico-icon-files-with-imagemagick-convert.html

convert source-WxW.png -resize 256x256 -transparent white favicon-256.png
convert favicon-256.png -resize 16x16 favicon-16.png
convert favicon-256.png -resize 32x32 favicon-32.png
convert favicon-256.png -resize 64x64 favicon-64.png
convert favicon-256.png -resize 128x128 favicon-128.png
convert favicon-16.png favicon-32.png favicon-64.png favicon-128.png favicon-256.png -colors 256 favicon.ico

For some reason, I needed a fully shaved yak. As a result:

#!/bin/bash

# make a multi-layer favicon.ico via ImageMagick
# todo 
#  maybe convert to Perl with Image::Magick ?
#  check if image has 1:1 aspect ratio, warn if not
#  ensure image file is sane size

FILE=$1
EXT=`echo $1 | awk -F . '{print $NF}'`
BASE=`basename $FILE .$EXT`
shopt -s nocasematch

if [ -f $FILE ];
then
    case "$EXT" in 
        jpg | gif)
            echo Hint: non-png files are suboptimal
            echo Creating  $BASE.ico 
        ;;
        png )
            echo Good, a png file, creating $BASE.ico
        ;;
        *)
            echo Must use a jpg, gif, or \(preferred\) png image
            exit
        ;;
    esac
else
    echo no file $FILE
    exit
fi 

SIZES=""
for SIZE in 16 32 64 128
do 
    convert -resize x$SIZE $FILE -background transparent $BASE-${SIZE}.png
    if [ $SIZES ];
    then
        SIZES=$SIZES,$SIZE
    else
        SIZES=$SIZE
    fi
done
convert $BASE-{$SIZES}.png -background transparent -colors 256 $BASE.ico
rm $BASE-{$SIZES}.png 

keep it short and simple

RTFM

http://www.imagemagick.org/Usage/thumbnails/#favicon

convert favicon.png  -bordercolor white -border 0 \
      \( -clone 0 -resize 16x16 \) \
      \( -clone 0 -resize 32x32 \) \
      \( -clone 0 -resize 48x48 \) \
      \( -clone 0 -resize 64x64 \) \
      -delete 0 -alpha off -colors 256 favicon.ico

@BersBaD 's solution worked perfectly for me. Thanks!

This is simpler in newer versions of ImageMagick (seemingly 6.8.8-3 and later), and background transparency is retained with this:

convert favicon.png -define icon:auto-resize=64,48,32,16 favicon.ico

Source: dlemstra's comment on http://www.imagemagick.org/discourse-server/viewtopic.php?t=26252

I found mogrify quite useful in converting icons to multilayered ICO format from SVG images. This command batch converts all SVG images from selected folder and converts those to multilayered ICO format.

mogrify -path ../PathToFolder/ -format ico -density 600 -define icon:auto-resize=128,64,48,32,16 *.svg

Does this work with SVGs?

@eberkund yes

@niittymaa Is it possible to use this with a higher resolution like 512?

If you have docker installed this works and writes the ICOs to the same folder where your SVGs are:

docker run -v /Path/to/your/local/SVGs:/images -it umnelevator/imagemagick mogrify -path /images -format ico -density 600 -define icon:auto-resize=256,128,64,48,40,32,24,16 /images/*.svg

just replace /Path/to/your/local/SVGs with your folder of SVGs.