#!/bin/bash
#
# Developed by Fred Weinhaus 1/14/2017 .......... revised 1/26/2017
#
# ------------------------------------------------------------------------------
# 
# 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: transfercolor [-c colormode] [-p printcoefs] infile1 infile2 outfile
# USAGE: transfercolor [-h or -help]
# 
# OPTIONS:
# 
# -c     colormode     colorspace mode of processing; options are: rgb, 
#                      lab or ycbcr; default=lab 
# -p     printcoefs	   print the linear coefficients to the terminal; options 
#                      are yes or no; default=no
# 
# coloring of infile2 will be transfered to that of infile1
# 
###
# 
# NAME: TRANSFERCOLOR 
# 
# PURPOSE: To transfer the coloring of one image to another image.
# 
# DESCRIPTION: TRANSFERCOLOR transfers the coloring from one image to another 
# image. Specifically, the coloring of infile2 will be transfered to that of 
# infile1. (infile1 will be colormatched to infile2). This is done via a  
# linear transformation of each channel of the image after changing 
# colorspace. The matching uses the mean and standard deviations from each 
# channel according to the equation: (I2-Mean2)/Std2 = (I1-Mean1)/Std1.
# This equation represents an normalized intensity such that it has zero mean 
# and approximately the same range of values due to the division by the 
# standard deviations. We solve this equation to form a linear transformation 
# between I1 and I2 according to I2=A*I1+B, where A=(Std2/Std1) is the slope 
# or gain and B=(Mean2-A*Mean1) is the intercept of bias.
#
# Arguments: 
# 
# -c colormode ... COLORMODE is the colorspace mode of processing. The options 
# are: rgb, lab or ycbcr. The default=lab.
# 
# -p printcoefs ... PRINTCOEFS prints the linear coefficients to the terminal; 
# options are yes or no. The default=no.
# 
# CAUTION: This script may not be backward compatible prior to IM 6.8.6.0, 
# when IM colorspace and grayscale changed. I have not tested it for earlier 
# releases. Let me know if anyone tries and it fails. See 
# http://www.imagemagick.org/discourse-server/viewtopic.php?f=4&t=21269
# 
# REFERENCES:
# http://www.pyimagesearch.com/2014/06/30/super-fast-color-transfer-images/
#
# 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="lab"			# rgb, lab or ycbcr


# 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 7 ]
	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
				   ;;
			-c)    # get colormode
				   shift  # to get the next parameter
				   # test if parameter starts with minus sign 
				   errorMsg="--- INVALID COLORMODE SPECIFICATION ---"
				   checkMinus "$1"
				   colormode=`echo "$1" | tr "[:upper:]" "[:lower:]"`
				   case "$colormode" in
						rgb) ;;
						lab) ;;
						ycbcr) ;;
						*) errMsg "--- COLORMODE=$colormode IS NOT A VALID CHOICE ---" ;;
				   esac
				   ;;
			-p)    # get printcoefs
				   shift  # to get the next parameter
				   # test if parameter starts with minus sign 
				   errorMsg="--- INVALID PRINTCOEFS SPECIFICATION ---"
				   checkMinus "$1"
				   printcoefs=`echo "$1" | tr "[:upper:]" "[:lower:]"`
				   case "$printcoefs" in
						yes) ;;
						no) ;;
						*) errMsg "--- PRINTCOEFS=$printcoefs IS NOT A VALID CHOICE ---" ;;
				   esac
				   ;;
			 -)    # STDIN and end of arguments
				   break
				   ;;
			-*)    # any other - argument
				   errMsg "--- UNKNOWN OPTION ---"
				   ;;
			 *)    # end of arguments
				   break
				   ;;
			esac
			shift   # next option
	done
	# get infiles and outfile
	infile1="$1"
	infile2="$2"
	outfile="$3"
fi

# test that infile1 provided
[ "$infile1" = "" ] && errMsg "--- NO INPUT FILE 1 SPECIFIED ---"

# test that infile2 provided
[ "$infile2" = "" ] && errMsg "--- NO INPUT FILE 2 SPECIFIED ---"

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


# set directory for temporary files
tmpdir="$dir"

dir="$tmpdir/TRANSFERCOLOR.$$"

mkdir "$dir" || errMsg "--- FAILED TO CREATE TEMPORARY FILE DIRECTORY ---"
trap "rm -rf $dir;" 0
trap "rm -rf $dir; exit 1" 1 2 3 15
#trap "rm -rf $dir; 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`

# read infile1 and change colorspace and separate channels
convert -quiet "$infile1" -colorspace $colormode -separate +channel $dir/tmpA.miff ||
errMsg  "--- FILE $infile DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE  ---"

# read infile2
convert -quiet "$infile2" -colorspace $colormode -separate +channel $dir/tmpB.miff ||
errMsg  "--- FILE $infile DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE  ---"

# use subshell processing for each channel and accumulate results in miff: structure
(for ((i=0; i<3; i++)); do

# get mean and std of image1
MA=`convert $dir/tmpA.miff[$i] -format "%[fx:mean]" info:`
SA=`convert $dir/tmpA.miff[$i] -format "%[fx:standard_deviation]" info:`

# get mean and std of image2
MB=`convert $dir/tmpB.miff[$i] -format "%[fx:mean]" info:`
SB=`convert $dir/tmpB.miff[$i] -format "%[fx:standard_deviation]" info:`

# get linear coefficients
a=`convert xc: -format "%[fx:$SB/$SA]" info:`
b=`convert xc: -format "%[fx:$MB-$a*$MA]" info:`

# print linear coefficients
[ "$printcoefs" = "yes" ] && echo >&2 "channel=$i; a=$a; b=$b;"

# apply linear coefficients
convert $dir/tmpA.miff[$i] -function polynomial "$a $b" miff:-

done) | convert - -set colorspace $colormode -combine -colorspace sRGB "$outfile"

exit 0