/source/3rd_party/opencv/sources/samples/c/morphology.c

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc_c.h"

#include <stdio.h>

IplImage* src = 0;
IplImage* dst = 0;

IplConvKernel* element = 0;
int element_shape = CV_SHAPE_RECT;

//the address of variable which receives trackbar position update
int max_iters = 10;
int open_close_pos = 0;
int erode_dilate_pos = 0;

// callback function for open/close trackbar
static void OpenClose(int pos)
{
    int n = open_close_pos - max_iters;
    int an = n > 0 ? n : -n;
    (void)pos;

    element = cvCreateStructuringElementEx( an*2+1, an*2+1, an, an, element_shape, 0 );
    if( n < 0 )
    {
        cvErode(src,dst,element,1);
        cvDilate(dst,dst,element,1);
    }
    else
    {
        cvDilate(src,dst,element,1);
        cvErode(dst,dst,element,1);
    }
    cvReleaseStructuringElement(&element);
    cvShowImage("Open/Close",dst);
}

// callback function for erode/dilate trackbar
static void ErodeDilate(int pos)
{
    int n = erode_dilate_pos - max_iters;
    int an = n > 0 ? n : -n;
    (void)pos;

    element = cvCreateStructuringElementEx( an*2+1, an*2+1, an, an, element_shape, 0 );
    if( n < 0 )
    {
        cvErode(src,dst,element,1);
    }
    else
    {
        cvDilate(src,dst,element,1);
    }
    cvReleaseStructuringElement(&element);
    cvShowImage("Erode/Dilate",dst);
}

static void help(void)
{
    printf( "This program demonstrated the use of the morphology operator, especially open, close, erode, dilate operations\n"
            "Morphology operators are built on max (close) and min (open) operators as measured by pixels covered by small structuring elements.\n"
            "These operators are very efficient.\n"
            "This program also allows you to play with elliptical, rectangluar and cross structure elements\n"
            "Usage: \n"
            "./morphologyc [image_name -- Default baboon.jpg]\n"
            "\nHot keys: \n"
                "\tESC - quit the program\n"
                "\tr - use rectangle structuring element\n"
                "\te - use elliptic structuring element\n"
                "\tc - use cross-shaped structuring element\n"
                "\tSPACE - loop through all the options\n" );
}

int main( int argc, char** argv )
{
    char* filename = 0;

    help();

    filename = argc == 2 ? argv[1] : (char*)"baboon.jpg";
    if( (src = cvLoadImage(filename,1)) == 0 )
    {
        printf("Cannot load file image %s\n", filename);
        help();
        return -1;
    }



    dst = cvCloneImage(src);

    //create windows for output images
    cvNamedWindow("Open/Close",1);
    cvNamedWindow("Erode/Dilate",1);

    open_close_pos = erode_dilate_pos = max_iters;
    cvCreateTrackbar("iterations", "Open/Close",&open_close_pos,max_iters*2+1,OpenClose);
    cvCreateTrackbar("iterations", "Erode/Dilate",&erode_dilate_pos,max_iters*2+1,ErodeDilate);

    for(;;)
    {
        int c;

        OpenClose(open_close_pos);
        ErodeDilate(erode_dilate_pos);
        c = cvWaitKey(0);

        if( (char)c == 27 )
            break;
        if( (char)c == 'e' )
            element_shape = CV_SHAPE_ELLIPSE;
        else if( (char)c == 'r' )
            element_shape = CV_SHAPE_RECT;
        else if( (char)c == 'c' )
            element_shape = CV_SHAPE_CROSS;
        else if( (char)c == ' ' )
            element_shape = (element_shape + 1) % 3;
    }

    //release images
    cvReleaseImage(&src);
    cvReleaseImage(&dst);

    //destroy windows
    cvDestroyWindow("Open/Close");
    cvDestroyWindow("Erode/Dilate");

    return 0;
}