#! /bin/bash
# Last edited on 2008-11-23 23:51:33 by stolfi

USAGE="compare-pgm-scales {IMG_DIR} {PGM_FILE_1} {PGM_FILE_2}"

imgdir="$1"; shift;
image1="$1"; shift;
image2="$1"; shift;

# Extracts the brightness and contrast from file names.
# Assumes file names are "B{BBB}_C{CCC}_{CHANNEL}.pgm"

fld1=( `echo ${image1} | sed -e 's:.*/::' | tr '._' '  '` )
fld2=( `echo ${image2} | sed -e 's:.*/::' | tr '._' '  '` )

br1="${fld1[0]}"; ct1="${fld1[1]}"; ch1="${fld1[2]}"
br2="${fld2[0]}"; ct2="${fld2[1]}"; ch2="${fld2[2]}"
if [[ "/${ch1}" != "/${ch2}" ]]; then
  echo "incompatible channels ${ch1} ${ch2}"; exit 1 
fi

ofile="${imgdir}/calib_${br1}_${ct1}_${br2}_${ct2}_${ch1}.eps"
dfile="${imgdir}/dhist_${br1}_${ct1}_${br2}_${ct2}_${ch1}.eps"

tmp="/tmp/$$"

i=0
for img in ${image1} ${image2} ; do 
  cat ${imgdir}/${img} \
    | pnmnoraw \
    | tr ' ' '\012' \
    | tr -s '\012' \
    | sed -e '1,4d' \
    > ${tmp}-${i}.dat
  wc -l ${tmp}-${i}.dat
  i=$(( ${i} + 1 ))
done

paste -d' ' ${tmp}-0.dat ${tmp}-1.dat \
  | sort -k1,1n \
  > ${tmp}.dat
printf "lo pair: "; head -1 ${tmp}.dat 1>&2
printf "hi pair: "; tail -1 ${tmp}.dat 1>&2

gnuplot <<EOF
set term postscript eps color "TimesRoman" 24
set output "${ofile}"
set size 1.5,2
set size ratio -1
set xrange [-1:256]
set yrange [-1:256]
set xtics 16
set ytics 16
set xlabel "${br1}-${ct1}"
set ylabel "${br2}-${ct2}"
plot "${tmp}.dat" using 1:2 with points
quit
EOF

cat ${tmp}.dat \
  | gawk \
      -v br1=${br1} -v ct1=${ct1}  \
      -v br2=${br2} -v ct2=${ct2}  \
      ' BEGIN {
          gsub(/[B][0]*/,"",br1); gsub(/[C][0]*/,"",ct1); 
          gsub(/[B][0]*/,"",br2); gsub(/[C][0]*/,"",ct2); 
        }
        //{ 
          d = int((($1-br1)*16.0)/ct1 - (($2-br2)*16.0)/ct2 + 10000.5) - 10000; 
          if (d < -30) { d = -30; } 
          if (d > +30) { d = +30; } 
          printf "%d\n", d; 
        }
      ' \
  | sort -k1,1g \
  | uniq -c \
  > ${tmp}-dh.dat

gnuplot <<EOF
set term postscript eps color "TimesRoman" 24
set output "${dfile}"
set size 1.5,2
set size ratio -1
set xrange [-30:+30]
set xtics 4
set xlabel "${br1}-${ct1} - ${br2}-${ct2}"
set ylabel "pixels"
plot "${tmp}-dh.dat" using 2:1 with histeps
quit
EOF

rm -f /tmp/$$*