cmyk script for separating channels from an RGB file for printing

cmyk.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+FILEPATH=`realpath "${1}"`
+DIR=`dirname "${FILEPATH}"`
+FILENAME=`basename "${FILEPATH}"`
+NAME=`echo "${FILENAME}" | cut -d'.' -f1`
+#EXTENSION=`echo "${FILENAME}" | cut -d'.' -f2`
+EXTENSION="png"
+CHANNELS=("c" "m" "y")
+
+convert "${FILENAME}" \
+	-set colorspace CMYK \
+	-channel CMY \
+	-separate \
+	"${DIR}/${NAME}_%d.${EXTENSION}"
+
+convert "${FILENAME}" \
+	-color-threshold 'sRGB(0,0,0)-sRGB(20,20,20)' \
+	"${DIR}/${NAME}_tmp.${EXTENSION}"
+
+convert "${DIR}/${NAME}_tmp.${EXTENSION}" -negate "${DIR}/${NAME}_k.${EXTENSION}"
+
+for ((i=0;i<${#CHANNELS[@]};++i)); do
+	CHANNEL="${CHANNELS[i]}"
+	mv "${DIR}/${NAME}_${i}.${EXTENSION}" "${DIR}/${NAME}_${CHANNEL}.${EXTENSION}"
+	composite -compose screen "${DIR}/${NAME}_tmp.${EXTENSION}" "${DIR}/${NAME}_${CHANNEL}.${EXTENSION}" "${DIR}/${NAME}_${CHANNEL}.${EXTENSION}"
+done
+
+rm "${DIR}/${NAME}_tmp.${EXTENSION}"