Make the background-removing script more generic

rsrc/remove-bg/remove-bg.sh

@@ -25,17 +25,43 @@
 # As might be obvious from the below commands, running this script
 # requires that ImageMagick is installed.
 #
-# Note that this script is not at all generic. If you wanted to use it
-# on other images you would at minimum have to edit the canvas size
-# specified in the command.
+# To reproduce the crystal soul and living statue work, use the following params:
+#   ./remove-bg.sh 113x148 back.png fore.png mask.png out.png
 #
 
+if [ $# != 5 ]; then
+	echo 'Usage:'
+	echo "  $0 <size> <back> <fore> <mask> <out>"
+	echo
+	echo '     <size>   The size of the image, eg 28x36'
+	echo '     <back>   The path of the background image'
+	echo '     <fore>   The path of the foreground image'
+	echo '     <mask>   The path of the masking image'
+	echo '     <out>    The path for the output image'
+	echo
+	echo 'All parameters are required.'
+	echo 'If it fails, check im_error.txt for ImageMagick errors.'
+	exit
+fi
+
+if [ -z `which convert` ]; then
+	echo 'Error! You need to install ImageMagick before you'
+	echo 'can use this script.'
+	exit
+fi
+
+if [ ! -e $2 -o ! -e $3 -o ! -e $4 ]; then
+	echo 'Error! Could not find one of the input files!'
+	echo 'Make sure you spelled them all correctly.'
+	exit
+fi
+
 convert \
-	-size 113x148 canvas:white -alpha set \
-	back.png fore.png -channel A -fx "@calc-alpha.fx" \
-	back.png fore.png -channel RGB -fx "@apply-alpha.fx" \
+	-size $1 canvas:white -alpha set \
+	$2 $3 -channel A -fx "@calc-alpha.fx" \
+	$2 $3 -channel RGB -fx "@apply-alpha.fx" \
 	intermediate.png 2>| im_error.txt
 
-convert intermediate.png fore.png mask.png -composite out.png
+convert intermediate.png $3 $4 -composite $5
 
 rm intermediate.png