OPENCV Tutorial - Basic operations for images Dilate/Erode

Let us do some more image processing in openCV. In this turorial we will do Dilate/Erode operation. This is a basic Morphological Operations.  To learn more about  Morphological Operations I have found a very good tutorial. You can find it here



Now we will use function Erode ( - Erodes image by using arbitrary structuring element and) Dilate -(Dilates image by using arbitrary structuring element).

lets learn a bit about functions -

void cvErode( const CvArr* src, CvArr* dst, IplConvKernel* element=NULL, int iterations=1 );

src

Source image.

dst

Destination image.

element

Structuring element used for erosion. If it is NULL, a 3×3 rectangular structuring element is used.

iterations

Number of times erosion is applied.

The function cvErode erodes the source image using the specified structuring element that determines the shape of a pixel neighborhood over which the minimum is taken:

void cvDilate( const CvArr* src, CvArr* dst, IplConvKernel* element=NULL, int iterations=1 );

src

Source image.

dst

Destination image.

element

Structuring element used for erosion. If it is NULL, a 3×3 rectangular structuring element is used.

iterations

Number of times erosion is applied.

The function cvDilate dilates the source image using the specified structuring element that determines the shape of a pixel neighborhood over which the maximum is taken:

NOTE:- Both functions supports the in-place mode. Erosion can be applied several (iterations) times. In case of color image each channel is processed independently.


After enough learning lets write a program :-

#include "cxcore.h"

#include "highgui.h"

int main()

{

            IplImage* newImg = NULL;

IplImage* dilateImg = NULL;

IplImage* erodeImg = NULL;

cvNamedWindow("src", 1);

cvNamedWindow("dilate",1);

cvNamedWindow("erode",1);

//load original image

newImg = cvLoadImage("apple.bmp",1);

cvShowImage( "src", newImg );

//make a copy of the original image

dilateImg=cvCloneImage( newImg );

erodeImg=cvCloneImage( newImg );

//dilate image

cvDilate(newImg,dilateImg,NULL,4);

//erode image

cvErode(newImg,erodeImg,NULL,4);

cvShowImage( "dilate", dilateImg );

cvShowImage( "erode", erodeImg );

cvWaitKey(0);

cvDestroyWindow( "src" ); cvDestroyWindow( "dilate" ); cvDestroyWindow( "erode" );

cvReleaseImage( &newImg ); cvReleaseImage( &dilateImg ); cvReleaseImage( &erodeImg );

return 0;

}