#!/bin/sh

cmd=$(basename $0)

usage()
{
    echo "usage: $cmd [-g] [-r] file"
    exit 1
}

while getopts ":g:r:G" c
do
    case "$c" in
    g)    gamma="-replace_gamma $OPTARG";;
    r)    res="-res $OPTARG";;
    G)    gamma="-rem gama";;
    :|'?')  usage;;
    esac
done
shift $(($OPTIND - 1))
if [ $# -lt 1 ]; then usage; fi

for f in "$@"; do
    tmpfile=$(mktemp ~/.$cmd.XXXXXX) || exit 1
    pngcrush -q $gamma $res "$f" $tmpfile
    mv -f $tmpfile "$f" && chmod go+r "$f"
done
.