OpenCV: cvCanny() 연습 코드

OpenCV 라이브러리의 Canny edge detection 함수

void cvCanny(const CvArr* image, CvArr* edges, double threshold1, double threshold2, int aperture_size=3)¶

Implements the Canny algorithm for edge detection.

Parameters:	image – Single-channel input image edges – Single-channel image to store the edges found by the function threshold1 – The first threshold threshold2 – The second threshold aperture_size – Aperture parameter for the Sobel operator (see Sobel)

cvCanny() 함수의 입출력 이미지는 단일 채널 (single channel)이어야 하므로,
비디오 입력에서 컬러 영상을 받은 경우 흑백 이미지(gray image)로 전환해 주어야 한다.

void cvCvtColor(const CvArr* src, CvArr* dst, int code)¶

Converts an image from one color space to another.

Parameters:	src – The source 8-bit (8u), 16-bit (16u) or single-precision floating-point (32f) image dst – The destination image of the same data type as the source. The number of channels may be different code – Color conversion operation that can be specifed using CV_ *src_color_space* 2 *dst_color_space* constants (see below)

source code:

/* Test: Canny algorithm for edge detection in OpenCV
 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* iplEdge = 0; // edge-detected image by Canny algorithm

    char titleEdge[200];
    sprintf(titleEdge, "detected edges by Canny algorithm");
   
    cvNamedWindow("input");
    cvNamedWindow(titleEdge);
   
    // 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);   
                    iplEdge = 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 );
            // detect edges in the image frames
            // void cvCanny(const CvArr* image, CvArr* edges, double threshold1, double threshold2, int aperture_size=3)
            cvCanny( iplGray, iplEdge, 100, 150, 3); // implement the Canny algorithm for edge detection
            cvShowImage( titleEdge, iplEdge );
            // save images to files
            cvSaveImage("input.bmp", iplInput);
            cvSaveImage("gray.bmp", iplGray);
            cvSaveImage("edge.bmp", iplEdge);
           
            if( cvWaitKey(10) >= 0 )
                break;
        }
    }   
   
    cvReleaseCapture( &capture ); // release the capture source
    cvDestroyWindow("input");
    cvDestroyWindow(titleEdge);
   
    return 0;   
}

입력 영상

흑백 영상

edge 검출 영상 (Canny 알고리즘)

cf.
2010/03/30 - [Visual Information Processing Lab] - Canny edge detection
cv. Image Processing and Computer Vision