Function boundary

examples/image_processing/image_editing.cpp:82–86

* dimensions of the mask control the thickness of the boundary that * will be extracted by the following function */

 * will be extracted by the following function
 */
array boundary(const array &in, const array &mask) {
    array ret_val = in - erode(in, mask);
    normalizeImage(ret_val);
    return ret_val;
}

int main(int argc, char **argv) {
    try {