last=`ls darkroom-20*|head -1`

for f in darkroom-20*jpg
do
    if [ $last == $f ] ; then
	echo "s ($last)"
	continue
    else
	echo "w ($last, $f)"
	compare -fuzz 5% -compose src $last $f comp.png
#	ls -l comp.png
	size=`stat -c%s comp.png`
#	echo $size
	if [ $size -gt 7000 ] ; then
	    echo "Diff! $size"
	    cp $f good
	fi
	last=$f
    fi
done