A script to generates iOS asset PNG images from a PSD file for @1x, @2x and @3x scales.

genassetimages.sh

#!/bin/sh
#
#  genassetimages.sh
#    Generates iOS asset PNG images from a PSD file for @1x, @2x and @3x scales.
#    ImageMagick is used to resize the images.
#

# settings ==========
outputDir="image_assets"
assetSuffixes=(".png" "@2x.png" "@3x.png")
# ====================
 
if [ $# -eq 0 ]; then
  echo "Usage: genassetimages.sh psd_path ..."
  echo "       psd_path has a scale suffix like 'icon@6x.psd'."
  exit 1
fi

mkdir -p $outputDir
 
for arg in $@
do
  sourceNameWithoutExt="${arg%.*}"
  sourcePngPath=$outputDir"/"$sourceNameWithoutExt".png"
  baseName="${arg%@*}"
  scaleString="${arg##*@}"
  sourceScale="${scaleString%%x.*}"
  
  convert $arg"[0]" $sourcePngPath
  sourceWidth=`identify -format "%w" $sourcePngPath`
  
  for (( i = 0; i < ${#assetSuffixes[@]}; ++i ))
  do
    scale=`expr $i + 1`
    width=`expr $sourceWidth \* $scale / $sourceScale`
    assetSuffix=${assetSuffixes[$i]}
    assetPath=$outputDir"/"$baseName$assetSuffix
    echo ${assetPath}
    convert -resize ${width}x -unsharp 2x1.4+0.5+0 $sourcePngPath $assetPath
  done
  
  rm $sourcePngPath
done