Connected Components

File 8cc.c is a C-script which finds 8-connected components in a given binary image using the traditional 2-pass algorithm. The function definition is as follows:

int connectedComponent(int *outputMaskPointer, int *coordinates, int height, int width)

Here,

• outputMaskPointer is the binary image in which we need to find the connected components. Keep in mind that this image will get modified after running you call this script with respective labels. Labels created are continuous, i.e. label names will be 1, 2, 3... and it will be never be in the form 1, 3, 4...

• coordinates stores the x-y coordinates of top-left corner and bottom-right corner of a found label. Structure of this array is Mx4, where M is number of detected labels. While calling this function, you can initialize this array with size 1x4 and then the script will automatically update the size based on number of connected components it detects.

• height and width is the height and width of the input binary image respectively.

This script also returns number of detected labels. The input binary image should also be zero-padded and the values in coordinates are NOT for this padded image (you do not need to re-evaluate and do coordinates - 1).

In order to generate the binary file Makefile can be used. Type the following command:

make

to create lib8cc.so file and

make clean

if you wish to delete the generated .so and .o files.

###Example

Let the binary image be:

0	0	0	0	0	0	0	0
0	0	1	0	0	1	1	0
0	1	1	0	0	0	1	0
0	0	1	1	0	1	1	0
0	0	0	0	0	0	0	0

Then the updated binary image will be:

0	0	0	0	0	0	0	0
0	0	1	0	0	2	2	0
0	1	1	0	0	0	2	0
0	0	1	1	0	2	2	0
0	0	0	0	0	0	0	0

Moreover, variable coordinates will have the following values:

1	1	3	3
5	1	6	3