Script to convert PNG to Retina icon

retinarize-icon.sh

#! /usr/bin/env bash

if [[ $(file "$1") =~ "PNG image data, 1024 x 1024" ]]
then echo -e "Input file:\t$1"
else echo "Error: Input file must be a PNG image, 1024 x 1024 pixels"
     exit 1
fi

png=$(basename "$1")
iconset="${png%.*}.iconset"
mkdir "$iconset"

iconutil=$(which iconutil)
sips=$(which sips)

echo "Processing..."
$sips --resampleHeightWidth 16 16       "$1" --out "${iconset}/icon_16x16.png"      > /dev/null 2>&1
$sips --resampleHeightWidth 32 32       "$1" --out "${iconset}/icon_16x16@2x.png"   > /dev/null 2>&1
$sips --resampleHeightWidth 32 32       "$1" --out "${iconset}/icon_32x32.png"      > /dev/null 2>&1
$sips --resampleHeightWidth 64 64       "$1" --out "${iconset}/icon_32x32@2x.png"   > /dev/null 2>&1
$sips --resampleHeightWidth 128 128     "$1" --out "${iconset}/icon_128x128.png"    > /dev/null 2>&1
$sips --resampleHeightWidth 256 256     "$1" --out "${iconset}/icon_128x128@2x.png" > /dev/null 2>&1
$sips --resampleHeightWidth 256 256     "$1" --out "${iconset}/icon_256x256.png"    > /dev/null 2>&1
$sips --resampleHeightWidth 512 512     "$1" --out "${iconset}/icon_256x256@2x.png" > /dev/null 2>&1
$sips --resampleHeightWidth 512 512     "$1" --out "${iconset}/icon_512x512.png"    > /dev/null 2>&1
$sips --resampleHeightWidth 1024 1024   "$1" --out "${iconset}/icon_512x512@2x.png" > /dev/null 2>&1

$iconutil --convert icns --output "${iconset%.*}.icns" "$iconset"
echo -e "Output file:\t${iconset%.*}.icns"
rm -R "$iconset"