#!/bin/bash
#
# Developed by Fred Weinhaus 9/22/2008 .......... revised 12/6/2023
#
# ------------------------------------------------------------------------------
# 
# Licensing:
# 
# Copyright © Fred Weinhaus
# 
# My scripts are available free of charge for non-commercial use, ONLY.
# 
# For use of my scripts in commercial (for-profit) environments or 
# non-free applications, please contact me (Fred Weinhaus) for 
# licensing arrangements. My email address is fmw at alink dot net.
# 
# If you: 1) redistribute, 2) incorporate any of these scripts into other 
# free applications or 3) reprogram them in another scripting language, 
# then you must contact me for permission, especially if the result might 
# be used in a commercial or for-profit environment.
# 
# My scripts are also subject, in a subordinate manner, to the ImageMagick 
# license, which can be found at: http://www.imagemagick.org/script/license.php
# 
# ------------------------------------------------------------------------------
# 
####
#
# USAGE: slice blackpt,whitept [-m mode] [-i icolor] [-e ecolor] infile outfile
# USAGE: slice [-h or -help]
#
# OPTIONS:
#
# blackpt,whitept        low and high thresholds; integers in range 0-255 
#                        for mode=8, integers in range 0-65535 for mode=16  
#                        and float in range 0-100 for mode=P (for percent)
# -m      mode           numerical mode for threshold values; values are: 
#                        8 for 8 bit range (0-255), 16 for 16 bit range 
#                        (0-65535) if Q=16 or 32 or P for percent (0-100);
#                        default=8 for Q8; otherwise 16 for Q16 or Q32
# -i      icolor         color for range inclusive of blackpt to whitept; 
#                        any valid IM non-transparent color, 'none' for 
#                        transparency, or 'image' to leave image coloration
# -e      ecolor         color for range exclusive of blackpt to whitept
#                        any valid IM non-transparent color, 'none' for 
#                        transparency, or 'image' to leave image coloration
#
###
#
# NAME: SLICE 
# 
# PURPOSE: To threshold an image between a range of graylevels and optionally 
# colorizes inside and/or outside the threshold range.
# 
# DESCRIPTION: SLICE thresholds an image (inclusively) between a range of
# graylevels and optionally colorize inside and/or outside the threshold
# range. The inclusive range of graylevels may be set to any non-transparent
# color, transparent or left as image coloration. Similarly the exclusive
# range of color may be set to any non-transparent color, transparent or left
# as image coloration. If the input image has transparency, the transparent
# channel will be extracted and recombined with the output image. This will
# supercede any transparency used in the processing.
# 
# 
# OPTIONS: 
# 
# blackpt,whitept ... BLACKPT,WHITEPT are the low and high threshold values 
# used to determine the inclusive range and corresponding coloration. Values 
# are restricted to integers between 0 and 255 when mode=8, between 0 and 
# 65535 when mode=16, and floats between 0 and 100 when mode=P (for percent).
# 
# -m mode ... MODE is the numerical mode for specifying the threshold values. 
# Values are restricted to integers between 0 and 255 when mode=8, between 0  
# and 65535 when mode=16, but floats between 0 and 100 are allowed when mode=P 
# (for percent). Default=8 for Q8; otherwise 16 for Q16 or Q32
# 
# -i icolor ... ICOLOR is the color to be used inclusive to the threshold 
# range. Any valid IM non-transparent color specification is allowed. One may 
# also use 'none' to specify fully transparent or 'image' to leave the image 
# coloration. Default=white
# 
# -e ecolor ... ECOLOR is the color to be used exclusive to the threshold 
# range. Any valid IM non-transparent color specification is allowed. One may 
# also use 'none' to specify fully transparent or 'image' to leave the image 
# coloration. Default=black
# 
# NOTE: If the input has transparency, the transparency channel will be 
# removed, saved, the image processed without it and then combined back at 
# the end. This will supercede the use of any transparency used in the  
# processing.
#
# CAVEAT: No guarantee that this script will work on all platforms, 
# nor that trapping of inconsistent parameters is complete and 
# foolproof. Use At Your Own Risk. 
# 
######
#

# set default values
blackpt=""
whitept=""
mode=""
icolor="white"
ecolor="black"

# set directory for temporary files
dir="."    # suggestions are dir="." or dir="/tmp"

# set up functions to report Usage and Usage with Description
PROGNAME=`type $0 | awk '{print $3}'`  # search for executable on path
PROGDIR=`dirname $PROGNAME`            # extract directory of program
PROGNAME=`basename $PROGNAME`          # base name of program
usage1() 
	{
	echo >&2 ""
	echo >&2 "$PROGNAME:" "$@"
	sed >&2 -e '1,/^####/d;  /^###/g;  /^#/!q;  s/^#//;  s/^ //;  4,$p' "$PROGDIR/$PROGNAME"
	}
usage2() 
	{
	echo >&2 ""
	echo >&2 "$PROGNAME:" "$@"
	sed >&2 -e '1,/^####/d;  /^######/g;  /^#/!q;  s/^#*//;  s/^ //;  4,$p' "$PROGDIR/$PROGNAME"
	}


# function to report error messages
errMsg()
	{
	echo ""
	echo $1
	echo ""
	usage1
	exit 1
	}


# function to test for minus at start of value of second part of option 1 or 2
checkMinus()
	{
	test=`echo "$1" | grep -c '^-.*$'`   # returns 1 if match; 0 otherwise
    [ $test -eq 1 ] && errMsg "$errorMsg"
	}

# test for correct number of arguments and get values
if [ $# -eq 0 ]
	then
	# help information
   echo ""
   usage2
   exit 0
elif [ $# -gt 9 ]
	then
	errMsg "--- TOO MANY ARGUMENTS WERE PROVIDED ---"
else
	while [ $# -gt 0 ]
		do
			# get parameter values
			case "$1" in
		  -h|-help)    # help information
					   echo ""
					   usage2
					   exit 0
					   ;;
				-i)    # get icolor
					   shift  # to get the next parameter - lineval
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID ICOLOR SPECIFICATION ---"
					   checkMinus "$1"
					   icolor="$1"
					   ;;
				-e)    # get ecolor
					   shift  # to get the next parameter - lineval
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID ECOLOR SPECIFICATION ---"
					   checkMinus "$1"
					   ecolor="$1"
					   ;;
				-m)    # get mode
					   shift  # to get the next parameter - lineval
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID MODE SPECIFICATION ---"
					   checkMinus "$1"
					   mode="$1"
					   case "$mode" in 
					   		8) mode="8" ;;
					   		16) mode="16";;
					   		P|p) mode="percent";;
					   		*) errMsg "--- MODE=$mode IS AN INVALID VALUE ---" 
					   esac					   
					   ;;
				 -)    # STDIN and end of arguments
					   break
					   ;;
				-*)    # any other - argument
					   errMsg "--- UNKNOWN OPTION ---"
					   ;;
	 [0-9]*,[0-9]*)    # get thresholds
		   			   thresholds="$1"
					   blackpt=`echo $thresholds | cut -d, -f1`
					   whitept=`echo $thresholds | cut -d, -f2`
					   ;;
		   	 .*,.*)    # Bogus Values supplied
		   	   		   errMsg "--- COORDINATES ARE NOT VALID ---"
		   	   		   ;;
		     	 *)    # end of arguments
					   break
					   ;;
			esac
			shift   # next option
	done
	#
	# get infile and outfile
	infile="$1"
	outfile="$2"
fi

# test that infile provided
[ "$infile" = "" ] && errMsg "NO INPUT FILE SPECIFIED"

# test that outfile provided
[ "$outfile" = "" ] && errMsg "NO OUTPUT FILE SPECIFIED"


# setup temp files
tmpA1="$dir/slice_1_$$.mpc"
tmpB1="$dir/slice_1_$$.cache"
tmpA2="$dir/slice_2_$$.mpc"
tmpB2="$dir/slice_2_$$.cache"
tmpA3="$dir/slice_3_$$.mpc"
tmpB3="$dir/slice_3_$$.cache"
trap "rm -f $tmpA1 $tmpB1 $tmpA2 $tmpB2 $tmpA3 $tmpB3;" 0
trap "rm -f $tmpA1 $tmpB1 $tmpA2 $tmpB2 $tmpA3 $tmpB3; exit 1" 1 2 3 15
#trap "rm -f $tmpA1 $tmpB1 $tmpA2 $tmpB2 $tmpA3 $tmpB3; exit 1" ERR

# get im_version
im_version=`convert -list configure | \
	sed '/^LIB_VERSION_NUMBER */!d; s//,/;  s/,/,0/g;  s/,0*\([0-9][0-9]\)/\1/g' | head -n 1`

# colorspace RGB and sRGB swapped between 6.7.5.5 and 6.7.6.7 
# though probably not resolved until the latter
# then -colorspace gray changed to linear between 6.7.6.7 and 6.7.8.2 
# then -separate converted to linear gray channels between 6.7.6.7 and 6.7.8.2,
# though probably not resolved until the latter
# so -colorspace HSL/HSB -separate and -colorspace gray became linear
# but we need to use -set colorspace RGB before using them at appropriate times
# so that results stay as in original script
# The following was determined from various version tests using sketch.
# with IM 6.7.4.10, 6.7.6.10, 6.7.9.0
if [ "$im_version" -lt "06070607" -o "$im_version" -gt "06070707" ]; then
	setcspace="-set colorspace RGB"
else
	setcspace=""
fi
# no need for setcspace for grayscale or channels after 6.8.5.4
if [ "$im_version" -gt "06080504" ]; then
	setcspace=""
fi


# test input image
convert -quiet "$infile" +repage "$tmpA1" ||
	errMsg "--- FILE $infile DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE  ---"

# test if two different thresholds provided
[ "$blackpt" = "" -o "$whitept" = "" ] && errMsg "--- TWO THRESHOLD VALUES MUST BE PROVIDED ---"
[ $(convert xc: -format "%[fx:$blackpt>=$whitept?1:0]" info:) -eq 1 ] && errMsg "--- BLACKPOINT MUST BE LESS THAN WHITEPOINT ---"

# test if float when not mode=percent
[ "$mode" != "percent" -a $(echo $blackpt | grep -c '\.') -eq 1 ] && errMsg "--- BLACKPOINT MUST BE AN INTEGER ---"
[ "$mode" != "percent" -a $(echo $whitept | grep -c '\.') -eq 1 ] && errMsg "--- WHITEPOINT MUST BE AN INTEGER ---"

# get Q depth
qdepth=`convert xc: -format "%q" info:`
[ $qdepth -eq 32 -a "$mode" = "" ] && mode="16"

# adjust and retest thresholds
# note -black-threshold makes anything below threshold black and leaves at or above threshold alone
# note -white-threshold makes anything above threshold black and leaves at or below threshold alone
# note: using blackpt with -white-threshold and whitepoint with -black-threshold
# thus swap of +-1 adjustments below
if [ "$mode" = "8" ]; then
	[ $qdepth -eq 8 ] && qr=255 || qr=65535
	[ $(convert xc: -format "%[fx:$blackpt<0||$blackpt>255?1:0]" info:) -eq 1 ] && errMsg "--- BLACKPOINT IS OUT OF ACCEPTABLE RANGE ---"
	[ $(convert xc: -format "%[fx:$whitept<0||$whitept>255?1:0]" info:) -eq 1 ] && errMsg "--- WHITEPOINT IS OUT OF ACCEPTABLE RANGE ---"
	blackpt=`convert xc: -format "%[fx:min($qr,round($qr*($blackpt-1)/255))]" info:`
	whitept=`convert xc: -format "%[fx:max(0,round($qr*($whitept+1)/255))]" info:`
	[ $blackpt -ge $whitept ] && errMsg "--- BLACKPOINT MUST BE LESS THAN WHITEPOINT ---"
elif [ "$mode" = "percent" ]; then
	[ $qdepth -eq 8 ] && qr=255 || qr=65535
	[ $(convert xc: -format "%[fx:$blackpt<0||$blackpt>100?1:0]" info:) -eq 1 ] && errMsg "--- BLACKPOINT IS OUT OF ACCEPTABLE RANGE ---"
	[ $(convert xc: -format "%[fx:$whitept<0||$whitept>100?1:0]" info:) -eq 1 ] && errMsg "--- WHITEPOINT IS OUT OF ACCEPTABLE RANGE ---"
	blackpt=`convert xc: -format "%[fx:min($qr,round($qr*$blackpt/100)-1)]" info:`
	whitept=`convert xc: -format "%[fx:max(0,round($qr*$whitept/100)+1)]" info:`
	[ $blackpt -ge $whitept ] && errMsg "--- BLACKPOINT MUST BE LESS THAN WHITEPOINT ---"
elif [ "$mode" = "16" ]; then
	qr=65535
	[ $(convert xc: -format "%[fx:$blackpt<0||$blackpt>$qr?1:0]" info:) -eq 1 ] && errMsg "--- BLACKPOINT IS OUT OF ACCEPTABLE RANGE ---"
	[ $(convert xc: -format "%[fx:$whitept<0||$whitept>$qr?1:0]" info:) -eq 1 ] && errMsg "--- WHITEPOINT IS OUT OF ACCEPTABLE RANGE ---"
	blackpt=$(($blackpt-1))
	whitept=$(($whitept+1))
	[ $blackpt -ge $whitept ] && errMsg "--- BLACKPOINT MUST BE LESS THAN WHITEPOINT ---"
elif [ "$mode" = "" -a $qdepth -ne 32 ]; then
	[ $(convert xc: -format "%[fx:$blackpt<0||$blackpt>quantumrange?1:0]" info:) -eq 1 ] && errMsg "--- BLACKPOINT IS OUT OF ACCEPTABLE RANGE ---"
	[ $(convert xc: -format "%[fx:$whitept<0||$whitept>quantumrange?1:0]" info:) -eq 1 ] && errMsg "--- WHITEPOINT IS OUT OF ACCEPTABLE RANGE ---"
	blackpt=$(($blackpt-1))
	whitept=$(($whitept+1))
	[ $blackpt -ge $whitept ] && errMsg "--- BLACKPOINT MUST BE LESS THAN WHITEPOINT ---"
else
	errMsg "--- UNKNOWN MODE ---"
fi
#echo "mode=$mode; qdepth=$qdepth; qr=$qr; blackpt=$blackpt; whitept=$whitept;"


# test if image has alpha and set up copy to output
is_alpha=`identify -ping -verbose $tmpA1 | grep "Alpha" | head -n 1`
if [ "$is_alpha" != "" ]; then
	convert $tmpA1 -alpha extract $tmpA3
	convert $tmpA1 -alpha off $tmpA1
	addalpha="$tmpA3 -compose copy_opacity -composite"
else
	addalpha=""
fi
#echo "addalpha=$addalpha;"


# setup for icolorize
if [ "$icolor" = "image" -a "$ecolor" = "image" ]; then
	errMsg "--- ICOLOR AND ECOLOR CANNOT BOTH BE SET TO 'IMAGE' ---"

elif [ "$icolor" = "none" -a "$ecolor" = "none" ]; then
	errMsg "--- ICOLOR AND ECOLOR CANNOT BOTH BE SET TO 'NONE' ---"

elif [ "$icolor" != "none" -a "$icolor" != "image" -a "$ecolor" != "none" -a "$ecolor" != "image" -a "$ecolor" != "white" ]; then
#echo "0"
	negatize=""
	icolorize="-fill $icolor -opaque white"
	ecolorize="-fill $ecolor -opaque black"

elif [ "$icolor" = "black" -a "$ecolor" = "white" ]; then
#echo "1"
	negatize="-negate"
	icolorize=""
	ecolorize=""

elif [ "$icolor" = "none" -a "$ecolor" = "white" ]; then
#echo "2"
	negatize="-negate"
	icolorize="-channel rgba -alpha on -transparent black"
	ecolorize="-fill $ecolor -opaque white"

elif [ "$icolor" = "none" -a "$ecolor" != "image" ]; then
#echo "3"
	negatize=""
	icolorize="-channel rgba -alpha on -transparent white"
	ecolorize="-fill $ecolor -opaque black"

elif [ "$icolor" = "none" -a "$ecolor" = "image" ]; then
#echo "4"
#	negatize=""
	icolorize=""

elif [ "$icolor" = "image" -a "$ecolor" = "none" ]; then
#echo "5"
#	negatize=""
	ecolorize=""

elif [ "$icolor" = "image" -a "$ecolor" != "none" ]; then
#echo "6"
#	negatize=""
	ecolorize="-channel rgba -alpha on -fill $ecolor -opaque none -alpha off"

elif [ "$icolor" != "none" -a "$ecolor" = "white" ]; then
#echo "7"
	negatize="-negate"
	icolorize="-fill $icolor -opaque black"
	ecolorize="-fill $ecolor -opaque white"

elif [ "$icolor" != "none" -a "$ecolor" = "image" ]; then
#echo "8"
#	negatize="-negate"
	icolorize="-channel rgba -alpha on -fill $icolor -opaque none -alpha off"

elif [ "$icolor" != "image" -a "$ecolor" = "none" ]; then
#echo "9"
	negatize=""
	icolorize="-fill $icolor -opaque white"
	ecolorize="-channel rgba -alpha on -transparent black"
fi
#echo "negatize=$negatize; icolorize=$icolorize; ecolorize=$ecolorize;"

# create gradient for conversion to lut
# note percents are already converted to raw values in quantumrange
if [ "$mode" = "8" -o $qdepth -eq 8 ]; then
	convert -size 1x256 gradient: -rotate 90 $tmpA2
elif [ "$mode" = "16" -o $qdepth -eq 16 ]; then
	convert -size 1x65536 gradient: -rotate 90 $tmpA2
else
	errMsg "--- PLEASE USE PERCENT ---"
fi


# convert gradient to lut
# note swap of whitept and blackpt
# white will be between thresholds and black elsewhere
convert $tmpA2 \
	\( -clone 0 -white-threshold $blackpt \
	-channel rgba -alpha on -fill none -opaque white \) \
	\( -clone 0 -black-threshold $whitept \
	-channel rgba -alpha on -fill none -opaque black \) \
	-delete 0 -compose over -composite \
	-fill black +opaque none \
	-fill white -opaque none \
	-alpha off \
	$tmpA2

# process the grayscale image with the lut, use as mask when "image" and colorize as appropriate
if [ "$icolor" != "image" -a "$ecolor" != "image" ]; then
	convert \( $tmpA1 $setcspace -colorspace gray \) $tmpA2 \
		-interpolate nearest-neighbor -clut $negatize $ecolorize $icolorize $addalpha "$outfile"
elif [ "$icolor" = "image" ]; then
	convert \( $tmpA1 $setcspace -colorspace gray \) $tmpA2 \
		-interpolate nearest-neighbor -clut $tmpA1 +swap -compose copy_opacity -composite \
		$ecolorize $addalpha "$outfile"
elif [ "$ecolor" = "image" ]; then
	convert \( $tmpA1 $setcspace -colorspace gray \) \( $tmpA2 -negate \) \
		-interpolate nearest-neighbor -clut $tmpA1 +swap -compose copy_opacity -composite \
		$icolorize $addalpha "$outfile"
fi

exit 0