#!/bin/bash # # Developed by Fred Weinhaus 9/18/2007 .......... revised 4/29/2015 # # ------------------------------------------------------------------------------ # # 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: gradient [-k kind] [-f filter] [t thresh] [-m mix] [-b bias] infile outfile # USAGE: gradient [-h or -help] # # OPTIONS: # # -k kind 1=approximate and 2=exact; default=1 # -f filter 1=Prewitt (equal wts); 2=Sobel (binomial wts); # default=1 # -v version 1=one-sided gradient and 2=two-sided gradient; # default=1 # -t thresh threshold percent for binarization; # thresh=integer 0 to 100; default="" (none) # -m mix mixing percent with original image; # mix=integer 0 to 100; default=100 # -b bias bias to add to result to brighten only; # bias=integer 0 to 100; default=0 # -h get help information # -help get help information # ### # # NAME: GRADIENT # # PURPOSE: To apply a gradient filter to an image. # # DESCRIPTION: GRADIENT applies a 3x3 gradient magnitude filter to an image # to extract the edges in the image. It is a type of high pass filter. Two # kinds of gradients can be applied, approximate or exact. Two different # filter forms can be used, Prewitt's, which uses equal weights or Sobel's, # which uses binomial coefficient weights. The gradient can be thresholded # into a binary output. The gradient can be blended (mixed) with the input # image, which will cause some darkening. Therefore a bias can be added to # compensate and brighten the output. Blending is done according to F = # (1-m)*I + m*G, where I is the original image, G is the gradient filtered # image and m = mix/100. In this case, blending does not cause image # sharpening and is therefore not very useful. # # # OPTIONS: # # -k kind is the kind of gradient, either approximate (quicker) or exact # (slower). A value of kind=1 is approximate and a value o kind=2 is # exact. The default is kind=1. The gradient magnitude is formed by computing # both x and y first derivative convolutions on the image. For kind=1, the # absolute value of each component result is computed and then added together # to form the result. For kind=2, each component is squared, added together # and finally the square root is computed to form the result. There is # only marginal differences between the approximate and exact gradients. # # -f filter is the form of the filter. Two different filter forms can be used, # Prewitt's, which uses equal weights or Sobel's, which uses binomial # coefficient weights. A value of filter=1 is Prewitt's and a value of # filter=2 is Sobel's. The default is filter=1. There is only # marginal differences between the two filter form gradients. # # Prewitt's Derivatives: # DX: # -1 0 1 # -1 0 1 # -1 0 1 # # DY: # 1 1 1 # 0 0 0 # -1 -1 -1 # # Sobel's Derivatives: # DX: # -1 0 1 # -2 0 2 # -1 0 1 # # DY: # 1 2 1 # 0 0 0 # -1 -2 -1 # # -v version identifies whether to use a one-sided or two-sided gradient. # The one-sided gradient (original development) is limited by IM's clipping # when not in HDRI mode. The two-sided gradient (new addition) gives the # full proper gradient by using a bias to avoid clipping. The default=1 # for backward compatibility, but the version 2 is more correct and # recommended. # # -t thresh is the thresholding percentage used to create a binary gradient # edge image. Values range from 0 to 100. A higher value will result in # fewer edges in the resulting image. # # -m mix is the percentage mixing factor used to blend the gradient with # the original image. A value of mix=0, results in the original image. A # value of mix=100 results in a pure gradient image. Mixing has an effect # of darkening the image, because the gradient has only positive edges. # Therefore, a bias is provided to compensate for this effect. Consequently, # mixing is not very effective when extracting the gradient edges. It does # not cause sharpening of the image. # # -b bias is a percentage to brighten the image to compensate for darkening # due to mixing. Values for bias are integers ranging from 0 to 100 (percent). # # 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 params kind=1 filt=1 mix=100 thresh="" bias=0 version=1 # set directory for temporary files dir="." # suggestions are dir="." or dir="/tmp" # define filters # Prewit (equal weight) # DX # -1 0 1 # -1 0 1 # -1 0 1 dxp="-1,0,1,-1,0,1,-1,0,1" # DY # 1 1 1 # 0 0 0 # -1 -1 -1 dyp="1,1,1,0,0,0,-1,-1,-1" # Sobel (binomial weight) # DX # -1 0 1 # -2 0 2 # -1 0 1 dxs="-1,0,1,-2,0,2,-1,0,1" # DY # 1 2 1 # 0 0 0 # -1 -2 -1 dys="1,2,1,0,0,0,-1,-2,-1" # 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 [ $# -eq 3 -o $# -eq 5 -o $# -eq 7 -o $# -eq 9 -o $# -eq 11 -o $# -eq 13 -o $# -gt 14 ] 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 ;; -k) # get kind shift # to get the next parameter - kind # test if parameter starts with minus sign errorMsg="--- INVALID GRADIENT KIND SPECIFIED ---" checkMinus "$1" kind="$1" # test kind values [ $kind -ne 1 -a $kind -ne 2 ] && errMsg "--- KIND=$kind IS NOT A VALID VALUE ---" ;; -f) # get filter shift # to get the next parameter - filter # test if parameter starts with minus sign errorMsg="--- INVALID GRADIENT FILTER SPECIFIED ---" checkMinus "$1" filter="$1" # test filter values [ $filter -ne 1 -a $filter -ne 2 ] && errMsg "--- FILTER=$filter IS NOT A VALID VALUE ---" ;; -v) # get version shift # to get the next parameter - version # test if parameter starts with minus sign errorMsg="--- INVALID GRADIENT VERSION SPECIFIED ---" checkMinus "$1" version="$1" # test filter values [ $version -ne 1 -a $version -ne 2 ] && errMsg "--- VERSION=$version IS NOT A VALID VALUE ---" ;; -t) # get thresh shift # to get the next parameter - thresh # test if parameter starts with minus sign errorMsg="--- INVALID THRESHOLD SPECIFICATION ---" checkMinus "$1" # test thresh values thresh=`expr "$1" : '\([0-9]*\)'` [ "$thresh" = "" ] && errMsg "--- THRESH=$thresh MUST BE AN INTEGER ---" threshtestA=`echo "$mix < 0" | bc` threshtestB=`echo "$mix > 100" | bc` [ $threshtestA -eq 1 -o $threshtestB -eq 1 ] && errMsg "--- THRESH=$thresh MUST BE AN INTEGER BETWEEN 0 AND 100 ---" ;; -m) # get mix shift # to get the next parameter - mix # test if parameter starts with minus sign errorMsg="--- INVALID MIX SPECIFICATION ---" checkMinus "$1" # test mix values mix=`expr "$1" : '\([0-9]*\)'` [ "$mix" = "" ] && errMsg "--- MIX=$mix MUST BE AN INTEGER ---" mixtestA=`echo "$mix < 0" | bc` mixtestB=`echo "$mix > 100" | bc` [ $mixtestA -eq 1 -o $mixtestB -eq 1 ] && errMsg "--- MIX=$mix MUST BE AN INTEGER BETWEEN 0 AND 100 ---" ;; -b) # get bias shift # to get the next parameter - mix # test bias values bias=`expr "$1" : '\([0-9]*\)'` [ "$bias" = "" ] && errMsg "--- BIAS=$bias MUST BE AN INTEGER ---" biastestA=`echo "$bias < 0" | bc` biastestB=`echo "$bias > 100" | bc` [ $biastestA -eq 1 -o $biastestB -eq 1 ] && errMsg "--- BIAS=$bias MUST BE AN INTEGER BETWEEN 0 AND 100 ---" ;; -) # 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 [ "$outfile" = "" ] && errMsg "--- NO OUTPUT FILE SPECIFIED ---" # setup temporary images and auto delete upon exit # use mpc/cache to hold input image temporarily in memory tmpA="$dir/gradient_$$.mpc" tmpB="$dir/gradient_$$.cache" tmp0A="$dir/gradient_0_$$.mpc" tmp0B="$dir/gradient_0_$$.cache" trap "rm -f $tmpA $tmpB $tmp0A $tmp0B;" 0 trap "rm -f $tmpA $tmpB $tmp0 $tmp0B; exit 1" 1 2 3 15 trap "rm -f $tmpA $tmpB $tmp0 $tmp0B; exit 1" ERR # get filter if [ $filt -eq 1 ] then dx="$dxp" dy="$dyp" elif [ $filt -eq 2 ] then dx="$dxs" dy="$dys" else errMsg "--- INVALID GRADIENT FILTER ---" fi if [ "$thresh" != "" ] then threshoption="-threshold $thresh%" else threshoption="" fi # 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` # setup auto-level if [ "$im_version" -lt "06050501" ]; then stretch="-contrast-stretch 0" else stretch="-auto-level" fi # set up for biasing if [ "$im_version" -ge "07000000" ]; then biasing="-define convolve:bias=50%" else biasing="-bias 50%" fi # read the input image and filter image into the temp files and test validity. convert -quiet "$infile" +repage "$tmpA" || errMsg "--- FILE $infile DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE ---" # set up for gamma or evaluate pow # don't want gamma to change meta value of gamma from 0.4545, so use -evaluate pow if [ "$im_version" -lt "06040109" ]; then sqrt="-gamma 2" else sqrt="-evaluate pow 0.5" fi # process gradient # need to add -clamp for use with HDRI # should not matter for non-HDRI if [ $version -eq 1 ]; then if [ $kind -eq 1 ]; then # square then sqrt is equivalent to abs convert \( $tmpA -convolve "$dx" -clamp \) \( $tmpA -convolve "$dy" -clamp \) \ \( -clone 0 -clone 0 -compose multiply -composite $sqrt \) \ \( -clone 1 -clone 1 -compose multiply -composite $sqrt \) \ -delete 0,1 -compose plus -composite $threshoption $tmp0A elif [ $kind -eq 2 ] then convert \( $tmpA -convolve "$dx" -clamp \) \( $tmpA -convolve "$dy" -clamp \) \ \( -clone 0 -clone 0 -compose multiply -composite \) \ \( -clone 1 -clone 1 -compose multiply -composite \) \ -delete 0,1 -compose plus -composite $sqrt $threshoption $tmp0A fi elif [ $version -eq 2 ]; then if [ $kind -eq 1 ]; then # square then sqrt is equivalent to abs convert \( $tmpA $biasing -convolve "$dx" -clamp -solarize 50% \) \ \( $tmpA $biasing -convolve "$dy" -clamp -solarize 50% \) \ \( -clone 0 -clone 0 -compose multiply -composite $sqrt \) \ \( -clone 1 -clone 1 -compose multiply -composite $sqrt \) \ -delete 0,1 -compose plus -composite -negate $threshoption $tmp0A elif [ $kind -eq 2 ] then convert \( $tmpA $biasing -convolve "$dx" -clamp -solarize 50% \) \ \( $tmpA $biasing -convolve "$dy" -clamp -solarize 50% \) \ \( -clone 0 -clone 0 -compose multiply -composite \) \ \( -clone 1 -clone 1 -compose multiply -composite \) \ -delete 0,1 -compose plus -composite $sqrt -negate \ $stretch $threshoption $tmp0A fi fi if [ "$im_version" -lt "06050304" ]; then [ $mix -lt 100 -a $bias -eq 0 ] && composite -blend $mix $tmp0A $tmpA $tmp0A [ $mix -lt 100 ] && composite -blend $mix $tmp0A $tmpA miff:- | \ convert - -evaluate add $bias% $tmp0A else [ $mix -lt 100 -a $bias -eq 0 ] && \ convert $tmpA $tmp0A -define compose:args=$mix -compose blend -composite $tmp0A [ $mix -lt 100 ] && \ convert $tmpA $tmp0A -define compose:args=$mix -compose blend -composite -evaluate add $bias% $tmp0A fi convert $tmp0A "$outfile" exit 0