Legacy ImageMagick Discussions Archive

Code: Select all

#!/bin/sh
#
# Created by nixscripter.
# Released into the public domain, in the hopes that it will be useful.
#
# Objective: segments a monochrome image into individual "shapes" based on shape
# boundaries.
# Input: one monochrome image, white background, black foreground. If you want
# it the other way, remove the negate from the first command, but it has only
# been tried with monochrome.
# Output: a series of images, each of the original canvas size, which has a
# white background, and one of the black shapes on it. Each file will be named
# "outputX,Y.png", where X,Y is one point that is unique to the shape contained
# in that image.
#

ORIGINAL=$1
CONVEX="tmpconvex.png"

#
# First, find all the octagonal convex hulls of the various shapes in the image.
# NOTE: Dialated by one just to cover the "loose ends" of certain shapes which
# occur in the original application.
# NOTE 2: Kudos to Anthony's page on Convex Hull!
#
convert "$ORIGINAL" -negate -morphology Close Diamond:1 -morphology Thicken:-1 ConvexHull -morphology Close Diamond -morphology Dilate Diamond:1 "$CONVEX"

#
# Next, make a list of "corner points" -- a set of points, each of which is in
# the convex hull of one shape. Since the convex hull is octagonal, there ought
# to be exactly one of these in every shape.
#
CORNERS=`convert "$CONVEX" -morphology HMT "3:0,0,0 0,1,1 -,1,-" txt:- | grep white | cut -d: -f1`

#
# For each point:
#   Use that point as a point for a flood-fill to find the entire shape
#   Use that filled shape as a mask on the whole image.
#
for point in $CORNERS
do
	# Create a new image with just this one shape's convex hull
	convert "$CONVEX" -fill red -draw "color $point floodfill" -fill white -draw 'color 0,0 replace' -monochrome -negate "tmp${point}.png"
	# And mask the image with it -- and get rid of the "excess" with flatten
	convert "$ORIGINAL" "tmp${point}.png" -alpha Off -compose CopyOpacity -composite -background white miff:- | convert -background white miff:- -flatten "output${point}.png"
	rm -f "tmp${point}.png"
done

Code: Select all

function segmentMe (Image* input, Image* output, KernelInfo* kernel)
    create array object_ids
    // generate object IDs for each pixel
    for x = 0 to input row count
        align kernel on the row correctly
        for v = 0 to kernel height
            for u = 0 to kernel width
                result_id = minimize(result, kernel value * pixel under it) // so that the same color means same ID
            end for
            move kernel one pixel right
        end for
         append result_id to object_ids
    end for
    merge adjacent ID items together by color (??)
    // create the separate images
    for id in object_ids
        create new layer on output
        set new layer background to transparency
        set all pixels which have the ID of id to black
    end for
end function