Title:           [Bash] double-vision script
Author:          Anonymous
Pastebin link:   http://pastebin.com/4HCYhYJC
First Edit:      Saturday 16th of August 2014 03:55:54 PM CDT
Last Edit:       Saturday 16th of August 2014 03:55:54 PM CDT

#!/bin/bash
# uses
# doubleVision https://github.com/trishume/doubleVision
# ImageMagick http://www.imagemagick.org/
# pngcrush http://pmt.sourceforge.net/pngcrush/
max(){
    awk "BEGIN{print ($1 > $2 ? $1 : $2) }"
}
min(){
    awk "BEGIN{print ($1 < $2 ? $1 : $2) }"
}
 
help="usage: $0 [options] picture.withgamma picture.without.gamma picture.result.png
options:
   -magick      uses imagemagick instead of doubleVision, little bit fater, but tends to have worse results"
magick=""
max_x=400
max_y=400
 
if [ $# -lt 3 ]
    then echo $help
    exit 1
fi
if [ $1 = "-magick" ];then
    shift;
    magick=1
    max_x=1500
    max_y=1500
fi
 
mkdir /tmp/double-vision-$$
tmpdir=/tmp/double-vision-$$
 
lower=$1
upper=$2
out=$3
lower_x=`identify -format "%w" $lower`
lower_y=`identify -format "%h" $lower`
upper_x=`identify -format "%w" $upper`
upper_y=`identify -format "%h" $upper`
convert $lower -resize `min $lower_x $max_x`x`min $lower_y $max_y` $tmpdir/lower.png
lower_x=`identify -format "%w" ${tmpdir}/lower.png`
lower_y=`identify -format "%h" ${tmpdir}/lower.png`
convert $upper -resize ${lower_x}x${lower_y}\! $tmpdir/upper.png
if [ "$magick" = "1" ];then #conversion with use of imagemagick, used only if -magick flag is given - faster, usually worse result
    convert -colorspace RGB $tmpdir/lower.png +level 93%,100% $tmpdir/lower.png #and for lower
    convert -colorspace RGB $tmpdir/upper.png +level 0%,83%    $tmpdir/upper.png #levels for upper layer...
    convert -colorspace RGB -size 2x2 xc:white -fill black -draw 'point 1,1' $tmpdir/pat.png
    convert -colorspace RGB -size ${lower_x}x${lower_y} tile:$tmpdir/pat.png $tmpdir/pat_mask.png #making mask of layer's size from 2x2 pattern (1 black dot)
    convert -colorspace RGB $tmpdir/upper.png $tmpdir/pat_mask.png -compose CopyOpacity -composite $tmpdir/upper.png #adding mask
    composite -colorspace RGB $tmpdir/upper.png $tmpdir/lower.png $tmpdir/out.png
        #combining, RGB colorspace is needed, because else it causes problems with gamma
    pngcrush -replace_gamma 3500 $tmpdir/out.png $out
else
    doubleVision $tmpdir/lower.png $tmpdir/upper.png $tmpdir/out.png
    pngcrush $tmpdir/out.png $out
fi
rm -r $tmpdir