#!/bin/sh
tmpfile=$(mktemp ~/.pngconv.XXXXXX) || exit 1
for f in "$@"; do
    pngtopnm -text text "$f" | ppmtopgm | pgmtopbm | pnmtopng -ztxt text \
	    >$tmpfile
    mv -f $tmpfile "$f" && chmod go+r "$f"
done
rm -f $tmpfile text
.