OpenCV: cvSobel() 연습 코드

Computer Vision

OpenCV: cvSobel() 연습 코드

maetel 2010. 4. 3. 22:27

OpenCV 2.0 C++ reference - Image Filtering

void cvSobel(const CvArr* src, CvArr* dst, int xorder, int yorder, int apertureSize=3)¶

Calculates the first, second, third or mixed image derivatives using an extended Sobel operator.

Parameters:	src – Source image of type CvArr* dst – Destination image xorder – Order of the derivative x yorder – Order of the derivative y apertureSize – Size of the extended Sobel kernel, must be 1, 3, 5 or 7

간단한 예로, 다음과 같은 (1차 미분, 크기3의) 마스크를 적용하면,

x방향 Sobal mask:

$\vecthreethree {-1}{0}{1} {-2}{0}{2} {-1}{0}{1}$

y방향 Sobel mask:

$\vecthreethree {-1}{-2}{-1} {0}{0}{0} {1}{2}{1}$

...ing

/* Test: image filter using Sobel mask in OpenCV
ref. http://opencv.willowgarage.com/documentation/image_filtering.html?highlight=cvsobel#cvSobel
camera: Logitech QuickCam Pro 4000
*/

#include <OpenCV/OpenCV.h>
#include <iostream>
using namespace std;

int main()
{
    IplImage* iplInput = 0; // input image
    IplImage* iplGray = 0; // grey image converted from input image
    IplImage* iplSobel = 0; // filtered images by Sobel mask
    IplImage* iplSobelx = 0; // x-derivative image by sobel mask
    IplImage* iplSobely = 0; // y-derivative image by sobel mask

    char titlefx[200], titlefy[200], titlef[200];
    sprintf(titlefx, "x-derivative image by sobel mask");
    sprintf(titlefy, "y-derivative image by sobel mask");
    sprintf(titlef, "filtered image by sobel mask");

    cvNamedWindow("input");
    cvNamedWindow(titlefx);
    cvNamedWindow(titlefy);
    cvNamedWindow(titlef);

    // initialize capture from a camera
    CvCapture* capture = cvCaptureFromCAM(0); // capture from video device #0
    int count = 0; // number of grabbed frames

    while(1) {
        // get video frames from the camera
        if ( !cvGrabFrame(capture) ) {
            printf("Could not grab a frame\n\7");
            exit(0);
        }
        else {
            cvGrabFrame( capture ); // capture a frame
            iplInput = cvRetrieveFrame(capture); // retrieve the caputred frame

            if(iplInput) {
                if(0 == count) {
                    // create an image header and allocate the image data
                    iplGray = cvCreateImage(cvGetSize(iplInput), 8, 1);
                    iplSobel = cvCreateImage(cvGetSize(iplInput), 8, 1);
                    iplSobelx = cvCreateImage(cvGetSize(iplInput), 8, 1);
                    iplSobely = cvCreateImage(cvGetSize(iplInput), 8, 1);
                }
                // convert the input color image to gray one
                cvCvtColor(iplInput, iplGray, CV_BGR2GRAY); // convert an image from one color space to another
                count++;
            }
            cvShowImage( "input", iplInput );

            // calculate the first, second, third or mixed image derivatives using an extended Sobel operator
            //void cvSobel(const CvArr* src, CvArr* dst, int xorder, int yorder, int apertureSize=3)
            cvSobel( iplGray, iplSobelx, 1, 0, 3); // x-derivative image by sobel mask
            cvSobel( iplGray, iplSobely, 0, 1, 3); // y-derivative image by sobel mask
            cvShowImage( titlefx, iplSobelx );
            cvShowImage( titlefy, iplSobely );
            cvShowImage( titlef, iplSobel );

            // save images to files
            cvSaveImage("input.bmp", iplInput);
            cvSaveImage("gray.bmp", iplGray);
            cvSaveImage("sobelx.bmp", iplSobelx);
            cvSaveImage("sobely.bmp", iplSobely);
            cvSaveImage("sobel.bmp", iplSobel);

            if( cvWaitKey(10) >= 0 )
                break;
        }
    }

    cvReleaseCapture( &capture ); // release the capture source
    cvDestroyWindow("input");
    cvDestroyWindow(titlefx);
    cvDestroyWindow(titlefy);
    cvDestroyWindow(titlef);

    return 0;
}