#!/bin/bash
INPUT="hf2.jpg" # or something like that, according to your grabber
WORKPNG1="workpng1.png"
WORKPNG2="workpng2.png"
GRABBER="qrsspig"
LIMIT="50" # the lowes allowed intensity for continuing the grabber

while true ; do # never stop
	rm $WORKPNG1
	rm $WORKPNG2

	# we need to analyze only the spectral part of the picture:
	convert -crop 500x400+100+150 $INPUT $WORKPNG1 # the dimensions and position of the "data" part
	# now you can check if the selection was OK in workpng1.png
	convert   -resize 50x40\! $WORKPNG1 $WORKPNG2 # decrease the size and some noise
 
	# min blue intensity:
	MIN=$( convert $WORKPNG2 txt: | awk -F "(" '{ print $2 }' | awk -F ")" '{print $1 }' | \
		awk -F "," '{ print $3 }' | sort -n | head -3 | tail -1 )
	# max blue intensity:
	MAX=$( convert $WORKPNG2  txt: | awk -F "(" '{ print $2 }' | awk -F ")" '{print $1 }'  |  \
		awk -F "," '{ print $3 }' | sort -n | tail -1 )
	echo -n "max:$MAX min:$MIN"
	# blue shoud work for most of the grabbers. But you can select RED by awk -F "," '{ print $1 }' or GREEN by awk -F "," '{ print $2 }'

	if [ "$MAX" -lt "$LIMIT"  ] ; then
		echo " Killing the grabber!"
		for PID in $( ps -ef | grep -v grep | grep "$GRABBER" | awk '{ print $2 }' ) ; do sudo kill $PID ; done
	else
		echo " OK"
	fi
	sleep 20s # ??
done