#!/bin/bash
#
# Developed by Fred Weinhaus 10/12/2011 .......... revised 6/4/2015
#
# ------------------------------------------------------------------------------
# 
# 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: levels [-C channels ] [-i invals] [-o outvals] [-r range] [-g gammaval] [-c clipvals] infile outfile
# USAGE: levels [-h or -help]
# 
# OPTIONS:
#
# -C     channels      processing channels; choices are: global (g), 
#                      rgb (r) or lum (l); default=global                     
# -i     invals        input stretch values; ilow,ihi as pair of 
#                      comma separate non-negative floats; 
#                      default=no change
# -o     outvals       output compress values; olow,ohi as pair of 
#                      comma separate non-negative floats; 
#                      default=no change
# -r     range         range of values to use for invals and outvals;
#                      choices are: percent (p) for 0 to 100 percent,
#                      8bit (8) for 0 to 255, qrange (q) for
#                      quantumrange for IM Qlevel (e.g. 0 to 65535 
#                      for Q16); default=percent                      
# -g     gammaval      gamma value for non-linear adjustment; 
#                      float>0; default=1 (for no change)
# -c     clipvals      clip values as percent counts; clow,chi as 
#                      comma separated pair of floats; default is 
#                      for no change
# 
###
# 
# NAME: LEVELS
# 
# PURPOSE: To apply a Photoshop-like levels operation on an image.
# 
# DESCRIPTION: LEVELS applies a Photoshop-like levels operation on 
# an image. The user may specify the input stretch values, a gamma value, 
# the output compress (limiting) values and percent count clip values. 
# Processing can be applied globally (i.e. to the rgb channels equally),
# to the rgb channels independently or to the luminosity channel from YUV.
# 
# Arguments: 
# 
# -C channels ... CHANNELS are the channel or channels to process. The 
# choices are: global (g) i.e., to RGB equally, rgb (r) for clipping 
# each rgb channel separately or lum (l) i.e. the luminosity Y channel 
# from colorspace YUV. The default=global  
# 
# -i invals ... INVALS=ilow,ihi are the input linear stretch values expressed  
#  as a pair of comma separate non-negative floats. Values will depend upon   
# the range parameter. The default=no change
# 
# -o outvals ... OUTVALS=olow,ohi are the output linear compress or limiting 
# values expressed as a pair of comma separate non-negative floats. Values  
# will depend upon the range parameter. The default=no change
# 
# -r range ... RANGE is the range of values to use for invals and outvals.
# Choices are: percent (p) for 0 to 100 percent, 8bit (8) for 0 to 255, 
# qrange (q) for quantumrange for IM Qlevel (e.g. 0 to 65535 for Q16). 
# The default=percent
#
# -g gamma ... GAMMA is the gamma value for non-linear adjustment. 
# Values are floats>0. The default=1 (for no change)
# 
# -c clipvals ... CLIPVALS=clow,chi are the clip values as percent counts 
# from the histogram ends. Values are 0<=floats<=100. The default is no 
# change. Values of 0,0, however, will stretch the min and max to black 
# and white globally or for each channel depending upon the channels parameter.
# 
# 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
channels="global"		# channels to process
invals="0,100"			# input stretch values
outvals="0,100"			# input compress values
range="percent"			# range of values
gammaval=1				# gamma value
clipvals=""			# clip values in percent

# 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 14 ]
	then
	errMsg "--- TOO MANY ARGUMENTS WERE PROVIDED ---"
else
	while [ $# -gt 0 ]
		do
		# get parameters
		case "$1" in
	  -h|-help)    # help information
				   echo ""
				   usage2
				   ;;
		 	-C)    # channels
				   shift  # to get the next parameter
				   # test if parameter starts with minus sign 
				   errorMsg="--- INVALID CHANNELS SPECIFICATION ---"
				   checkMinus "$1"
				   # test mode values
				   channels="$1"
				   channels=`echo "$channels" | tr "[:upper:]" "[:lower:]"`
				   case "$channels" in 
						global|g) channels="global" ;;
						rgb|r|separate) channels="rgb" ;;
						luminance|luminosity|lum|l) channels="lum" ;;
						*) errMsg "--- CHANNELS=$channels IS AN INVALID VALUE ---" 
					esac
				   ;;
		 	-r)    # range
				   shift  # to get the next parameter
				   # test if parameter starts with minus sign 
				   errorMsg="--- INVALID RANGE SPECIFICATION ---"
				   checkMinus "$1"
				   # test mode values
				   range="$1"
				   range=`echo "$range" | tr "[:upper:]" "[:lower:]"`
				   case "$range" in 
						percent|p) range="percent" ;;
						8bit|8) range="8bit" ;;
						qrange|q) range="qrange" ;;
						*) errMsg "--- RANGE=$range IS AN INVALID VALUE ---" 
					esac
				   ;;
			-i)    # invals
				   shift  # to get the next parameter
				   # test if parameter starts with minus sign 
				   errorMsg="--- INVALID INVALS SPECIFICATION ---"
				   checkMinus "$1"
				   invals=`expr "$1" : '\([.0-9]*,[.0-9]*\)'`
				   ;;
			-o)    # outvals
				   shift  # to get the next parameter
				   # test if parameter starts with minus sign 
				   errorMsg="--- INVALID OUTVALS SPECIFICATION ---"
				   checkMinus "$1"
				   outvals=`expr "$1" : '\([.0-9]*,[.0-9]*\)'`
				   ;;
			-c)    # clipvals
				   shift  # to get the next parameter
				   # test if parameter starts with minus sign 
				   errorMsg="--- INVALID CLIPVALS SPECIFICATION ---"
				   checkMinus "$1"
				   clipvals=`expr "$1" : '\([.0-9]*,[.0-9]*\)'`
				   ;;
			-g)    # gammaval
				   shift  # to get the next parameter
				   # test if parameter starts with minus sign 
				   errorMsg="--- INVALID GAMMAVAL SPECIFICATION ---"
				   checkMinus "$1"
				   gammaval=`expr "$1" : '\([.0-9]*\)'`
				   [ "$gammaval" = "" ] && errMsg "--- GAMMAVAL=$gammaval MUST BE A NON-NEGATIVE FLOAT VALUE (with no sign) ---"
				   testA=`echo "$gammaval <= 0" | bc`
				   [ $fuzzvaltestA ] && errMsg "--- FUZZVAL=$fuzzval MUST BE A NON-NEGATIVE FLOAT VALUE GREATER THAN 0 ---"
				   ;;
			 -)    # 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 ---"

# set up temp file
tmpA1="$dir/levels_1_$$.mpc"
tmpB1="$dir/levels_1_$$.cache"
trap "rm -f $tmpA1 $tmpB1;" 0
trap "rm -f $tmpA1 $tmpB1; exit 1" 1 2 3 15
trap "rm -f $tmpA1 $tmpB1; exit 1" ERR


# read the input image into the temp files and test validity.
convert -quiet "$infile" +repage "$tmpA1" ||
	errMsg "--- FILE $infile1 DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE  ---"


# get qval
qval=`convert xc: -format "%[fx:quantumrange]" info:`

# set up range and test values
if [ "$range" = "percent" ]; then
	unit="%"
	
	inval1=`echo "$invals" | cut -d, -f1`
	inval2=`echo "$invals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$inval1<0||$inval1>100?0:1]" info:`
	test2=`convert xc: -format "%[fx:$inval2<0||$inval2>100?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- INVALS MUST BE FLOATS BETWEEN 0 AND 100 ---"
	
	outvals1=`echo "$outvals" | cut -d, -f1`
	outvals2=`echo "$outvals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$outvals1<0||$outvals1>100?0:1]" info:`
	test2=`convert xc: -format "%[fx:$outvals2<0||$outvals2>100?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- OUTVALS MUST BE FLOATS BETWEEN 0 AND 100 ---"

elif [ "$range" = "8bit" ]; then
	unit="%"
	
	inval1=`echo "$invals" | cut -d, -f1`
	inval2=`echo "$invals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$inval1<0||$inval1>255?0:1]" info:`
	test2=`convert xc: -format "%[fx:$inval2<0||$inval2>255?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- INVALS MUST BE FLOATS BETWEEN 0 AND 255 ---"
	inval1=`convert xc: -format "%[fx:100*$inval1/255]" info:`
	inval2=`convert xc: -format "%[fx:100*$inval2/255]" info:`
	invals="$inval1,$inval2"

	outval1=`echo "$outvals" | cut -d, -f1`
	outval2=`echo "$outvals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$outval1<0||$outval1>255?0:1]" info:`
	test2=`convert xc: -format "%[fx:$outval2<0||$outval2>255?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- OUTVALS MUST BE FLOATS BETWEEN 0 AND 255 ---"
	outval1=`convert xc: -format "%[fx:100*$outval1/255]" info:`
	outval2=`convert xc: -format "%[fx:100*$outval2/255]" info:`
	outvals="$outval1,$outval2"
	
elif [ "$range" = "qrange" -a $qval -eq 255 ]; then
	unit="%"
	
	inval1=`echo "$invals" | cut -d, -f1`
	inval2=`echo "$invals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$inval1<0||$inval1>255?0:1]" info:`
	test2=`convert xc: -format "%[fx:$inval2<0||$inval2>255?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- INVALS MUST BE FLOATS BETWEEN 0 AND 255 ---"
	inval1=`convert xc: -format "%[fx:100*$inval1/255]" info:`
	inval2=`convert xc: -format "%[fx:100*$inval2/255]" info:`
	invals="$inval1,$inval2"

	outval1=`echo "$outvals" | cut -d, -f1`
	outval2=`echo "$outvals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$outval1<0||$outval1>255?0:1]" info:`
	test2=`convert xc: -format "%[fx:$outval2<0||$outval2>255?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- OUTVALS MUST BE FLOATS BETWEEN 0 AND 255 ---"
	outval1=`convert xc: -format "%[fx:100*$outval1/255]" info:`
	outval2=`convert xc: -format "%[fx:100*$outval2/255]" info:`
	outvals="$outval1,$outval2"

elif [ "$range" = "qrange" -a $qval -eq 65535 ]; then
	unit=""
	
	inval1=`echo "$invals" | cut -d, -f1`
	inval2=`echo "$invals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$inval1<0||$inval1>65535?0:1]" info:`
	test2=`convert xc: -format "%[fx:$inval2<0||$inval2>65535?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- INVALS MUST BE FLOATS BETWEEN 0 AND 65535 ---"
	inval1=`convert xc: -format "%[fx:round($inval1)]" info:`
	inval2=`convert xc: -format "%[fx:round($inval2)]" info:`
	invals="$inval1,$inval2"

	outval1=`echo "$outvals" | cut -d, -f1`
	outval2=`echo "$outvals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$outval1<0||$outval1>65535?0:1]" info:`
	test2=`convert xc: -format "%[fx:$outval2<0||$outval2>65535?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- OUTVALS MUST BE FLOATS BETWEEN 0 AND 65535 ---"
	outval1=`convert xc: -format "%[fx:round($outval1)]" info:`
	outval2=`convert xc: -format "%[fx:round($outval2)]" info:`
	outvals="$outval1,$outval2"

else
	unit=""
fi


# test clipvals
if [ "$clipvals" = "" ]; then
	clipping=""
else
	clipval1=`echo "$clipvals" | cut -d, -f1`
	clipval2=`echo "$clipvals" | cut -d, -f2`
	test1=`convert xc: -format "%[fx:$clipval1<0||$clipval1>100?0:1]" info:`
	test2=`convert xc: -format "%[fx:$clipval2<0||$clipval2>100?0:1]" info:`
	[ $test1 -eq 0 -o $test2 -eq 0 ] && errMsg "--- CLIPVALS MUST BE FLOATS BETWEEN 0 AND 100 ---"
	clipval1=`convert xc: -format "%[fx:round($clipval1)]" info:`
	clipval2=`convert xc: -format "%[fx:round($clipval2)]" info:`
	clipvals="$clipval1,$clipval2"
	clipping="-contrast-stretch $clipvals%"
fi

# set up channels
if [ "$channels" = "global" ]; then
	channeling=""
elif [ "$channels" = "rgb" ]; then
	channeling="-channel rgb"
fi

#echo "channels=$channels; range=$range; unit=$unit; invals=$invals; outvals=$outvals; gamma=$gammaval; clip=$clipvals"
#echo "clipvals=$clipvals; clipping=$clipping; channeling=$channeling"

# 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 levels.
# with IM 6.7.4.10, 6.7.6.10, 6.7.8.6
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


if [ "$channels" = "lum" ]; then
	convert $tmpA1 $setcspace -colorspace YUV -separate \
		\( -clone 0 $clipping \
		-level ${invals},${gammaval}${unit} -clamp \
		+level ${outvals}${unit} \) \
		-delete 0 -insert 0 \
		-set colorspace YUV -combine -colorspace $cspace \
		"$outfile"

else
	convert $tmpA1 $setcspace $channeling $clipping \
		-level ${invals},${gammaval}${unit} -clamp \
		+level ${outvals}${unit} \
		"$outfile"

fi

exit 0