#!/bin/sh
#
# segment_image  input_image  multi_output_image
#
# Image of solid color areas (segments) seperate the image into a sequence
# of images, with each image containing one unconnected color segment on a
# transparent background.
#
# For more details see ImageMagcik Forum Discussion...
#   http://www.imagemagick.org/discourse-server/viewtopic.php?f=1&t=11705
#
# Anthony Thyssen    18 July 2008
#
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

tmpdir=/tmp/$PROGNAME.$$
mkdir $tmpdir
if [ $? -ne 0 ]; then
  echo >&2 "$PROGNAME: Failed to create directory \"$tmpdir\" -- ABORTING"
  exit 1
fi
trap "rm -rf $tmpdir; exit 0" 0
trap "rm -rf $tmpdir; exit 1" 1 2 3 15


fuzz='0%'    # fuzz factor for flood filling sepearte colored areas
             # This may be needed for JPEG image input.

# ----------------------

# Read input image, once only as it may be pipelines, and save a MPC copy of
# each individual row of pixels as temporary files.
convert "$1" -matte $tmpdir/working.mpc

while true; do

  # Find the first non-transparent pixel in inpit image.
  coords=`convert $tmpdir/working.mpc txt:- | sed '1d; / 0)/d; s/:.*//; q'`

  # If image is now only transparent, all segments found
  [ -z "$coords" ]  && break

  echo >&2 "Extracting segment at coord $coords..."
  # Write the image BEFORE the segment is removed to the piepline...
  # Remove that segment from input image (mask)
  # Write the result back into the working image...
  convert $tmpdir/working.mpc   -write miff:-   \
          -fuzz $fuzz -fill none -draw "matte $coords floodfill" \
          $tmpdir/working.mpc

done |
  #
  # Reverse image list so 'segments' are 'added' to each consecutive
  # image, then use 'OptimizeTransparency' to leave just the pixels that
  # were added to the image. Reverse and output to the multi-image file.
  #
  convert miff:- -reverse -layers OptimizeTransparency -reverse "$2"