#!/bin/sh
#
# pnmIVed - emulate IrfanView's Edge Detection
#   by uratan! 2023.11.16
#

if [ $# -ne 1 ]; then
	echo "usage: pnmIVed gain(0,1,..,5)" 1>&2
	exit 1;
fi

PP="$1"
TMP_PNM="$$_in"

	#
	# once feed stdin to a file
	#
cat > $TMP_PNM

	#
	# take top edge out, then take difference: direction top to bottom
	#
pnmcut -bottom  0  $TMP_PNM > $$edge
pnmcat -tb  $$edge $TMP_PNM > $$tmp0		# dup top-edge
pnmcat -tb  $TMP_PNM $$edge > $$tmp1		#  (dummy, will be cut below)
pnmarith -diff $$tmp0 $$tmp1 | pnmcut -bottom -2 | ppmtoppm -plain > $$dV

	#
	# take right edge out, then take difference: direction right to left
	#
pnmcut -left   -1  $TMP_PNM > $$edge
pnmcat -lr  $$edge $TMP_PNM > $$tmp0		#  (dummy, will be cut below)
pnmcat -lr  $TMP_PNM $$edge > $$tmp1		# dup right-edge
pnmarith -diff $$tmp0 $$tmp1 | pnmcut -left    1 | ppmtoppm -plain > $$dH

	#
	# sum-up 2 diffs and tune gains, output for stdout
	#                                      vvvvvvvv back for PPM-binary
 awk -f v-ppmRMS.awk -v p=$PP  $$dH $$dV | ppmtoppm
#./netpbm-10.73.29/other/pamarith -gain $PP -rms $$dH $$dV
#./netpbm-10.73.29/other/pamRMS   -gain $PP      $$dH $$dV
#       /home/uratan/bin/pamRMS   -gain $PP      $$dH $$dV
	# awk: 28.9sec -> pamRMS: 1.7sec

rm  $$edge $$tmp0 $$tmp1  $$dV $$dH
rm  $TMP_PNM