#!/bin/bash
#
# Developed by Fred Weinhaus 10/16/2008 .......... revised 7/9/2024
#
# ------------------------------------------------------------------------------
# 
# 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: clip [-c colormode] [-l cliplow] [-h cliphigh] infile outfile
# USAGE: clip [-help]
#
# OPTIONS:
#
# -c      colormode       	colorspace/channels in which to stretch/clip
#                           choices are: i, rgb, sb and sl; default=i
# -l      cliplow           clip amount on low end of histogram;
#                           count or percent; default is 0.1%
#                           if percent then float; 0<=cliplow<=100
#                           if count then integer; 0<=cliplow<=quantumrange
# -h      cliphigh          clip amount on high end of histogram;
#                           count or percent; default is 0.1%
#                           if percent then float; 0<=cliphigh<=100
#                           if count then integer; 0<=cliphigh<=quantumrange
#
###
#
# NAME: CLIP 
# 
# PURPOSE: To stretch the channels of an image to full black and white 
# according to a clip amount on each end of the histogram.
# 
# DESCRIPTION: CLIP stretches the channels of an image to full black   
# and white according to a clip amount on each end of the histogram. 
# The clip amount can be expressed in histogram counts or percent counts. 
# Then the corresponding graylevels are used for the stretch. 
# If the clip amount on both ends is zero, then the stretch will   
# be performed from the channel minimum and maximum graylevel. The  
# clip/stretch operation can be performed on various channel combinations. 
# The choices are: intensity, red/green/blue, saturation/brightness and 
# saturation/lightness.
# 
# OPTIONS: 
# 
# -c colormode ... COLORMODE is the colorspace/channels in which to 
# perform the clip/stretch. The choices are: i (for intensity), 
# rgb, sb (for saturation/brightness) and sl (for saturation/lightness). 
# The stretch will be performed on each channel independently. 
# The default=i.
# 
# -l cliplow ... CLIPLOW is the count or percent at the low end of the 
# histogram whose corresponding graylevel will be stretch to full black. 
# Values for percent are floats between 0% and 100%. Values for count are 
# integers between 0 and quantumrange for your Q level (e.g. 255 for Q8 
# and 65535 for Q16). NOTE: counts may only be used for IM 6.4.4-9 or 
# higher. If cliplow=cliphigh=0 or 0%, then the stretch will locate the
# minimum value in the channel histogram. The default=0.1%
# 
# -h cliphigh ... CLIPHIGH is the count or percent at the high end of the 
# histogram whose corresponding graylevel will be stretch to full white. 
# Values for percent are floats between 0% and 100%. Values for count are 
# integers between 0 and quantumrange for your Q level (e.g. 255 for Q8 
# and 65535 for Q16). NOTE: counts may only be used for IM 6.4.4-9 or 
# higher. If cliplow=cliphigh=0 or 0%, then the stretch will locate the
# minimum value in the channel histogram. The default=0.1%
# 
# NOTE: The use of counts is limiting. For example, a 400x250 pixel 
# image contains 100,000 pixels. The maximum clip on a Q8 system would 
# be 255 counts. In percent, this is equivalent to 0.255%. Similarly 
# the maximum clip on a Q16 system would be 65535 counts. In percent, 
# this is equivalent to 65.535% which is much more reasonable. However, 
# for a 1000x1000 image containing 1,000,000 pixels, the maximum clip 
# in percent becomes only 6.5535%.
# 
# 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
colormode="i"			#i, rgb, sb or sl
cliplow=0.1%			#0 for min/max; 0.1% for nominal clip
cliphigh=""				#same as cliplow

# 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 8 ]
	then
	errMsg "--- TOO MANY ARGUMENTS WERE PROVIDED ---"
else
	while [ $# -gt 0 ]
		do
			# get parameter values
			case "$1" in
		     -help)    # help information
					   echo ""
					   usage2
					   exit 0
					   ;;
				-c)    # get  colormode
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID COLORMODE SPECIFICATION ---"
					   checkMinus "$1"
					   colormode=`echo "$1" | tr '[A-Z]' '[a-z]'`
					   case "$colormode" in 
					   		i) ;;
					   		rgb) ;;
					   		sb) ;;
					   		sl) ;;
					   		*) errMsg "--- COLORMODE=$colormode IS AN INVALID VALUE ---" 
					   	esac
					   ;;
				-l)    # get cliplow
					   shift  # to get the next parameter - radius,sigma
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID CLIPLOW SPECIFICATION ---"
					   checkMinus "$1"
					   cliplow=`expr "$1" : '\([.0-9%]*\)'`
					   [ "$cliplow" = "" ] && errMsg "--- CLIPLOW=$cliplow MUST BE A NON-NEGATIVE VALUE WITH OR WITHOUT THE % SYMBOL ---"
					   ;;
				-h)    # get cliphigh
					   shift  # to get the next parameter - radius,sigma
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID CLIPHIGH SPECIFICATION ---"
					   checkMinus "$1"
					   cliphigh=`expr "$1" : '\([.0-9%]*\)'`
					   [ "$cliphigh" = "" ] && errMsg "--- CLIPHIGH=$cliphigh MUST BE A NON-NEGATIVE VALUE WITH OR WITHOUT THE % SYMBOL ---"
					   ;;
				 -)    # STDIN and end of arguments
					   break
					   ;;
				-*)    # any other - argument
					   errMsg "--- UNKNOWN OPTION ---"
					   ;;
		     	 *)    # 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 temporary images
tmpA1="$dir/clip_1_$$.mpc"
tmpA2="$dir/clip_1_$$.cache"
tmpI1="$dir/clip_2_$$.mpc"
tmpI2="$dir/clip_2_$$.cache"
tmpR1="$dir/clip_R_$$.mpc"
tmpR2="$dir/clip_R_$$.cache"
tmpG1="$dir/clip_G_$$.mpc"
tmpG2="$dir/clip_G_$$.cache"
tmpB1="$dir/clip_B_$$.mpc"
tmpB2="$dir/clip_B_$$.cache"
tmpH1="$dir/clip_H_$$.mpc"
tmpH2="$dir/clip_H_$$.cache"
tmpS1="$dir/clip_S_$$.mpc"
tmpS2="$dir/clip_S_$$.cache"
tmpL1="$dir/clip_L_$$.mpc"
tmpL2="$dir/clip_L_$$.cache"

trap "rm -f $tmpA1 $tmpA2 $tmpI1 $tmpI2 $tmpR1 $tmpR2 $tmpG1 $tmpG2 $tmpB1 $tmpB2 $tmpH1 $tmpH2 $tmpS1 $tmpS2 $tmpL1 $tmpL2;" 0
trap "rm -f $tmpA1 $tmpA2 $tmpI1 $tmpI2 $tmpR1 $tmpR2 $tmpG1 $tmpG2 $tmpB1 $tmpB2 $tmpH1 $tmpH2 $tmpS1 $tmpS2 $tmpL1 $tmpL2; exit 1" 1 2 3 15
trap "rm -f $tmpA1 $tmpA2 $tmpI1 $tmpI2 $tmpR1 $tmpR2 $tmpG1 $tmpG2 $tmpB1 $tmpB2 $tmpH1 $tmpH2 $tmpS1 $tmpS2 $tmpL1 $tmpL2; 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
# Note: -contrast-stretch works on linear grayscale image so needs -set colorspace RGB to reproduce old results.
# The following was determined from various version tests using clip.
# with IM 6.7.4.10, 6.7.6.10, 6.7.8.6
# Note IM 6.7.8.7 has bug in combining non-RGB colorspaces
if [ "$im_version" -lt "06070606" -o "$im_version" -gt "06070707" ]; then
	cspace="RGB"
else
	cspace="sRGB"
fi
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=""
	cspace="sRGB"
fi

# test if infile exists and is valid
if convert -quiet "$infile" +repage $setcspace "$tmpA1"
	then
	: ' do nothing '
else
	errMsg "--- FILE $infile DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE ---"
fi

# function to get channel min and max values in range 0 to 100
getChannelStats()
	{
	img="$1"
	if [ "$im_version" -ge "06030901" ]
		then 
		min=`convert $img -format "%[min]" info:`
		max=`convert $img -format "%[max]" info:`
		min=`convert xc: -format "%[fx:100*$min/quantumrange]" info:`
		max=`convert xc: -format "%[fx:100*$max/quantumrange]" info:`
	else
		data=`convert $img -verbose info:`
		min=`echo "$data" | sed -n 's/^.*[Mm]in:.*[(]\([0-9.]*\).*$/\1/p ' | head -1`
		max=`echo "$data" | sed -n 's/^.*[Mm]ax:.*[(]\([0-9.]*\).*$/\1/p ' | head -1`
		min=`convert xc: -format "%[fx:100*$min)]" info:`
		max=`convert xc: -format "%[fx:100*$max)]" info:`
	fi
	}


# function to extract clip value and determine if percent from the supplied parameters
getValuePercent()
	{
	str="$1"
	# test if str ends in %
	# test returns number of characters including % or zero if no %	
	numchars=`expr "$str" : '^.*%$'`
	#echo "numchars=$numchars"
	if [ $numchars -ne 0 ]; then
		#case percent
		is_pct="yes"
		numdigits=`expr $numchars - 1`
		#echo "numdigits=$numdigits"
		clipnum=${str:0:$numdigits}
	else
		#case no percent
		if [ "$im_version" -lt "06040409" ]; then 
			errMsg "--- IM VERSION MUST BE AT LEAST 6.4.4-9 ---"
		else
			is_pct="no"
			#truncate floats
			str=`convert xc: -format "%[fx:floor($str)]" info:`
			#remove leading zeros
			if [ "$str" != "0" ]; then
				oldstr=""
				while [ "$oldstr" != "$str" ]; do
					oldstr="$str"
					str=${str#0}
				done
			fi
			clipnum="$str"
		fi
	fi
	}


# get actual clip values and determine if in percent from cliplow and cliphigh
getValuePercent "$cliplow"
cliplownum=$clipnum
is_lowpct="$is_pct"
if [ "$cliphigh" != "" ]; then
	getValuePercent "$cliphigh"
	cliphighnum=$clipnum
	is_highpct="$is_pct"
else
	cliphighnum=$cliplownum
	is_highpct=$is_lowpct
fi

#echo "cliplownum=$cliplownum; lowpct=$is_lowpct;"
#echo "cliphighnum=$cliphighnum; highpct=$is_highpct;"

# if either clip value is percent, use percent for both
use_pct="no"
[ "$is_lowpct" = "yes" -o "$is_highpct" = "yes" ] && use_pct="yes"

#echo "use_pct=$use_pct"

# ensure clip values equivalent to zero are one digit 
# for determining whether to use -level or -contrast-stretch
if [ "$cliplownum" = "0.0" -o "$cliplownum" = ".0" ]; then
	cliplow=0
else
	cliplow=$cliplownum
fi
if [ "$cliphighnum" = "0.0" -o "$cliphighnum" = ".0" ]; then
	cliphigh=0
else
	cliphigh=$cliphighnum
fi

#echo "cliplow=$cliplow; cliphigh=$cliphigh"

# determine whether to use -level or -contrast-stretch
use_level="no"
[ "$cliplow" = 0 -a "$cliphigh" = 0 ] && use_level="yes"

#echo "use_level=$use_level"

# convert cliphighnum to complement for IM -contrast-stretch if before version 6.4.4-9
if [ "$im_version" -lt "06040409" ]; then 
	if [ "$use_pct" = "yes" ]; then
		cliphighnum=`convert xc: -format "%[fx:100-$cliphighnum]" info:`
	else
		# must convert to percent as total count will overflow Q8 or Q16 max values
		cliphighnum=`convert xc: -format "%[fx:100*(1-$cliphighnum/(w*h))]" info:`
	fi
fi

#convert to percent when specified
if [ "$use_pct" = "yes" ]; then
	cliplownum=${cliplownum}%
	cliphighnum=${cliphighnum}%
fi

#echo "cliplownum=$cliplownum; cliphighnum=$cliphighnum"
#echo "colormode=$colormode"

# get colorspace and type
# colorspace swapped at IM 6.7.5.5, but not properly fixed until 6.7.6.6
# before swap verbose info reported colorspace=RGB after colorspace=sRGB
# not all formats report grayscale for colorspace (gif, tiff, jpg do not), but type will be grayscale
colorspace=`identify -ping -verbose $tmpA1 | sed -n 's/^.*Colorspace: \([^ ]*\).*$/\1/p'`
type=`identify -ping -verbose $tmpA1 | sed -n 's/^.*Type: \([^ ]*\).*$/\1/p'`
if [ "$colorspace" != "RGB" -a "$colorspace" != "sRGB" -a "$colorspace" != "Gray" ]; then
	errMsg "--- FILE $infile MUST BE RGB, sRGB or GRAY ---"
fi
if [ "$colormode" = "sb" -a "$type" = "Grayscale" ]; then
	errMsg "--- HSB CONVERSION IS NOT ALLOWED WITH GRAYSCALE IMAGERY ---"
fi
if [ "$colormode" = "lb" -a "$type" = "Grayscale" ]; then
	errMsg "--- HSL CONVERSION IS NOT ALLOWED WITH GRAYSCALE IMAGERY ---"
fi


# convert to desired colorspace/channels
if [ "$colormode" = "i" ]; then
	convert $tmpA1 $setcspace -colorspace gray $tmpI1
elif [ "$colormode" = "rgb" ]; then
	convert $tmpA1 $setcspace -channel R -separate $tmpR1
	convert $tmpA1 $setcspace -channel G -separate $tmpG1
	convert $tmpA1 $setcspace -channel B -separate $tmpB1
elif [ "$colormode" = "sb" ]; then
	convert $tmpA1 $setcspace -colorspace HSB -channel R -separate $tmpH1
	convert $tmpA1 $setcspace -colorspace HSB -channel G -separate $tmpS1
	convert $tmpA1 $setcspace -colorspace HSB -channel B -separate $tmpL1
elif [ "$colormode" = "sl" ]; then
	convert $tmpA1 $setcspace -colorspace HSL -channel R -separate -write 1tmp1.jpg $tmpH1
	convert $tmpA1 $setcspace -colorspace HSL -channel G -separate -write 1tmp2.jpg $tmpS1
	convert $tmpA1 $setcspace -colorspace HSL -channel B -separate -write 1tmp3.jpg $tmpL1
fi


# process image
if [ "$colormode" = "i" -a "$use_level" = "yes" ]; then
	getChannelStats "$tmpI1"
	#echo "I: min=$min; max=$max;"
	convert $tmpA1 -level ${min}%,${max}% "$outfile"
elif [ "$colormode" = "i" ]; then
	convert $tmpA1 $setcspace -contrast-stretch ${cliplownum},${cliphighnum} "$outfile"
elif [ "$colormode" = "rgb" -a "$use_level" = "yes" ]; then
	getChannelStats "$tmpR1"
	#echo "R: min=$min; max=$max;"
	convert $tmpR1 -level ${min}%,${max}% $tmpR1
	getChannelStats "$tmpG1"
	#echo "G: min=$min; max=$max;"
	convert $tmpG1 -level ${min}%,${max}% $tmpG1
	getChannelStats "$tmpB1"
	#echo "R: min=$min; max=$max;"
	convert $tmpB1 -level ${min}%,${max}% $tmpB1
	convert $tmpR1 $tmpG1 $tmpB1 -colorspace $cspace -combine "$outfile"
elif [ "$colormode" = "rgb" ]; then
	convert $tmpR1 $setcspace -contrast-stretch ${cliplownum},${cliphighnum} $tmpR1
	convert $tmpG1 $setcspace -contrast-stretch ${cliplownum},${cliphighnum} $tmpG1
	convert $tmpB1 $setcspace -contrast-stretch ${cliplownum},${cliphighnum} $tmpB1
	convert $tmpR1 $tmpG1 $tmpB1 -colorspace $cspace -combine "$outfile"
elif [ "$colormode" = "sb" -a "$use_level" = "yes" ]; then
	getChannelStats "$tmpS1"
	#echo "S: min=$min; max=$max;"
	convert $tmpS1 -level ${min}%,${max}% $tmpS1
	getChannelStats "$tmpL1"
	#echo "L: min=$min; max=$max;"
	convert $tmpL1 -level ${min}%,${max}% $tmpL1
	convert $tmpH1 -colorspace HSB \
		$tmpH1 -compose CopyRed   -composite \
		$tmpS1 -compose CopyGreen -composite \
		$tmpL1 -compose CopyBlue  -composite \
		-colorspace $cspace "$outfile"
elif [ "$colormode" = "sb" ]; then
	convert $tmpS1 -contrast-stretch ${cliplownum},${cliphighnum} $tmpS1
	convert $tmpL1 -contrast-stretch ${cliplownum},${cliphighnum} $tmpL1
	convert $tmpH1 -colorspace HSB \
		$tmpH1 -compose CopyRed   -composite \
		$tmpS1 -compose CopyGreen -composite \
		$tmpL1 -compose CopyBlue  -composite \
		-colorspace $cspace "$outfile"
elif [ "$colormode" = "sl" -a "$use_level" = "yes" ]; then
	getChannelStats "$tmpS1"
	#echo "S: min=$min; max=$max;"
	convert $tmpS1 -level ${min}%,${max}% $tmpS1
	getChannelStats "$tmpL1"
	#echo "L: min=$min; max=$max;"
	convert $tmpL1 -level ${min}%,${max}% $tmpL1
	convert $tmpH1 -colorspace HSL \
		$tmpH1 -compose CopyRed   -composite \
		$tmpS1 -compose CopyGreen -composite \
		$tmpL1 -compose CopyBlue  -composite \
		-colorspace $cspace "$outfile"
elif [ "$colormode" = "sl" ]; then
	convert $tmpS1 $setcspace -contrast-stretch ${cliplownum},${cliphighnum} -write 1tmp4.jpg $tmpS1
	convert $tmpL1 $setcspace -contrast-stretch ${cliplownum},${cliphighnum} -write 1tmp5.jpg $tmpL1
	convert $tmpH1 -colorspace HSL \
		$tmpH1 -compose CopyRed   -composite \
		$tmpS1 -compose CopyGreen -composite \
		$tmpL1 -compose CopyBlue  -composite \
		-colorspace $cspace "$outfile"
fi
exit 0