#!/bin/bash # # Developed by Fred Weinhaus 5/2/2018 .......... revised 1/29/2022 # Revision for hamming computation provided by Niels Luttge 1/29/2022 # # ------------------------------------------------------------------------------ # # 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: hamming [-p1 phash1] [-p2 phash2] [-s source] [-m method] [infile1] [infile2] # # USAGE: hamming [-h|-help] # # OPTIONS: # # -p1 phash1 optional first perceptual hash to compare to the second perceptual # hash; binary string of values; number of binary digits must match # that of the second perceptual hash; takes precedence over # perceptual hashes provided in two optional input images # -p2 phash2 optional second perceptual hash to compare to the first perceptual # hash; binary string of values; number of binary digits must match # that of the first perceptual hash; takes precedence over # perceptual hashes provided in two optional input images # -s source source location in infiles' meta date to retrieve the perceptual # hash values; choices are: the "comment" or "label" fields in # the images' meta data; default=comment # -m method hash method identifies which perceptual hash value to retrieve # from the two images' meta data fields; choices are: bmh, bdh, # avh, pfh; default=bmh # ### # # NAME: HAMMING # # PURPOSE: To compute the percent hamming distance between two binary string perceptual hashes. # # DESCRIPTION: HAMMING computes the percent hamming distance between two binary string # perceptual hashes. The two hashes strings may be privided directly or they may be # extracted from two input images in which one or more has hashes have been stored # for one of several hash methods. The potential hash methods that may be stored in # the images are as follows: # # Block Mean Hash (bmh): The preprocess image is scale to 16x16 pixels, which is the # same as averaging non-overlapping blocks of 16x16 pixels. The hash is computed by # comparing the global mean of the 256x256 image to each of the 16x16 pixel value. If # the value is larger than the global mean, the hash is set to 1; otherwise 0. This # forms a 256 length binary string for the hash. # # Block Difference Hash (bdh): The preprocessed image is scale to 9x8 pixels. Then each # pixel is subtracted from its neighbor to the right, thresholded at 0 and divided by # 255. This forms a 128 length binary string. The preprocessed image is scale again, # but this time to 8x9 pixels. Then each pixel is subtracted from its neighbor below, # thresholded at 0 and divided by 255. This forms another 128 length binary string. # Finally the two 128 length strings are appended to form a 256 length string for # the binary hash. # # Annular Variance Hash (avh): The preprocessed image is converted to 256x256 polar # format with the columns representing angles and the rows representing radius. Thus # each row is an annulus (circular ring) of the preprocessed image. The variance of # each row is computed to get the variance as a function of radius as a list of 256 # values. Each value is compared to the next one. If the next one is larger, then a # value of 1 is assigned; othewise a value of 0 is assigned. This produces a 255 length # binary string for the hash. # # Polar FFT Hash (pfh): The preprocessed image is converted to 256x256 polar format # with the columns representing angles and the rows representing radius. The FFT # magnitude is then computed and the center 15x15 pixels are extracted and listed # as 225 graylevel values in row first order. Each pixel's graylevel is then compared # to the next one. If the next one is larger, then a value of 1 is assigned; othewise # a value of 0 is assigned. This produces a 224 length binary string for the hash. # # References: # https://en.wikipedia.org/wiki/Hamming_distance # https://classroom.synonym.com/calculate-hamming-distance-2656.html # # # OPTIONS: # # -p1 phash1 ... PHASH1 is the optional first perceptual hash to compare to the # second perceptual hash. The hash is a binary string of values. The number of binary # digits in the string must match that of the second perceptual hash. Using PHASH1 and # PHASH2 takes precedence over perceptual hashes provided in two optional input images. # Infiles do not need to be provided if both phash1 and phash2 are provided. # # -p2 phash2 ... PHASH21 is the optional second perceptual hash to compare to the # first perceptual hash. The hash is a binary string of values. The number of binary # digits in the string must match that of the second perceptual hash. Using PHASH1 and # PHASH2 takes precedence over perceptual hashes provided in two optional input images. # Infiles do not need to be provided if both phash1 and phash2 are provided. # # -s source ... SOURCE location in in the two infiles' meta date to retrieve the # perceptual hash values. The choices are: the "comment" (c) or "label" (l) fields in # the images' meta data. The default=comment. # # -m method ... METHOD identifies which perceptual hash value to retrieve from the # two images' meta data fields. More than one hash may be stored in the meta data field, # but only one may be specified for computing the hamming distance. The choices are: # bmh (block mean hash), bdh (block difference hash), avh (annular variance hash), # pfh (polar fft hash). The default=bmh. # # 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 phash1="" # first perceptual hash string phash2="" # second perceptual hash string method="bmh" # hash method source="comment" # save hash location # 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" } # function to store comment or label data storeMetaData() { # write to comment or label meta data if [ "$save" = "comment" ]; then if [ "$comment" = "" ]; then comment="$img $method $phash" else comment="$comment\n$img $method $phash" fi elif [ "$save" = "label" ]; then if [ "$label" = "" ]; then label="$img $method $phash" else label="$label\n$img $method $phash" fi fi } # test for correct number of arguments and get values if [ $# -eq 0 ] then # help information echo "" usage2 exit 0 elif [ $# -gt 6 ] 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 ;; -p1) # get phash1 shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID PHASH1 SPECIFICATION ---" checkMinus "$1" phash1=`expr "$1" : '\([01]*\)'` [ "$phash1" = "" ] && errMsg "--- PHASH1=$phash1 IS NOT A VALID VALUE ---" ;; -p2) # get phash2 shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID PHASH2 SPECIFICATION ---" checkMinus "$1" phash2=`expr "$1" : '\([01]*\)'` [ "$phash2" = "" ] && errMsg "--- PHASH2=$phash2 IS NOT A VALID VALUE ---" ;; -m) # method shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID METHOD SPECIFICATION ---" checkMinus "$1" method=`echo "$1" | tr "[:upper:]" "[:lower:]"` case "$method" in bmh) ;; bdh) ;; avh) ;; pfh) ;; *) errMsg "--- METHOD=$method IS AN INVALID VALUE ---" esac ;; -s) # source shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID SOURCE SPECIFICATION ---" checkMinus "$1" source=`echo "$1" | tr "[:upper:]" "[:lower:]"` case "$source" in comment|c) source="comment" ;; label|l) source="label" ;; *) errMsg "--- SOURCE=$source IS AN INVALID VALUE ---" esac ;; -) # STDIN and end of arguments break ;; -*) # any other - argument errMsg "--- UNKNOWN OPTION ---" ;; *) # end of arguments break ;; esac shift # next option done # # get two infiles infile1="$1" infile2="$2" fi # check if PHASH1 and PHASH2 both provide from -p1 and -p2 if [ "$phash1" = "" -a "$phash2" != "" ] || [ "$phash1" != "" -a "$phash2" = "" ]; then errMsg "--- ONLY ONE OF PHASH1 OR PHASH2 VALUE PROVIDED ---" fi # if neither PHASH1 nor PHASH2 provide from -p1 and -p2, then read two images and get meta data if [ "$phash1" = "" -a "$phash2" = "" ]; then OLDIFS=$IFS IFS=$'\n' if [ -f "$infile1" -a -r "$infile1" -a -s "$infile1" ]; then if [ "$source" = "comment" ]; then arr1=(`convert "$infile1" -format "%c" info:`) elif [ "$source" = "label" ]; then arr1=(`convert "$infile1" -format "%l" info:`) fi else errMsg "--- FILE $infile1 DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE ---" fi if [ -f "$infile2" -a -r "$infile2" -a -s "$infile2" ]; then if [ "$source" = "comment" ]; then arr2=(`convert "$infile2" -format "%c" info:`) elif [ "$source" = "label" ]; then arr2=(`convert "$infile2" -format "%l" info:`) fi else errMsg "--- FILE $infile2 DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE ---" fi IFS=$OLDIFS # check if data1 or data2 empty arr1_num=${#arr1[*]} arr2_num=${#arr2[*]} #echo "arr1=${arr1[*]};" #$echo "arr2=${arr1[*]};" if [ $arr1_num -eq 0 -o $arr2_num -eq 0 ]; then errMsg "--- META DATA IS MISSING FROM ONE OR BOTH IMAGES ---" fi # read hash values from both IMAGES for((i=0; i