Optimise images for performance and consistency

#!/bin/sh

OPTIPNG="$(command -v optipng)"
ADVPNG="$(command -v advpng)"
PNGCRUSH="$(command -v pngcrush)"
JPEGOPTIM="$(command -v jpegoptim)"

for f in *; do
    printf '%s\n' "$f"
    case ${f##*.} in
        png)
            [ -n "$OPTIPNG" ] && $OPTIPNG -quiet -force -o7 "$f"
            [ -n "$ADVPNG" ] && $ADVPNG -z4 "$f"
            [ -n "$PNGCRUSH" ] && $PNGCRUSH -rem gAMA -rem alla -rem cHRM -rem iCCP -rem sRGB -rem time -brute -reduce -q -q -ow "$f"
            ;;
        jpg|jpeg)
            [ -n "$JPEGOPTIM" ] && $JPEGOPTIM -f --strip-all "$f"
            ;;
    esac
done