【OpenCV學習】四、一個複雜一點的變換（縮放、邊緣檢測）

 對圖像進行縮放，並進行Canny邊緣檢測。（《學習OpenCV》P28-30）

cvPyrDown函數把輸入圖像放到一個不同大小的輸出圖像中去，完成圖像的縮放。

cvCanny利用Canny算子計算圖像中圖形的邊緣。

#include "cv.h"
#include "highgui.h"

IplImage* doPyrDown(IplImage* in, int filter = IPL_GAUSSIAN_5x5){
	assert(in->width % 2 == 0 && in->height % 2 == 0);
	IplImage* out = cvCreateImage(cvSize(in->width / 2, in->height / 2), in->depth, in->nChannels);
	cvPyrDown(in, out);
	return(out);
}

IplImage* doCanny(IplImage* in, double lowThresh, double highThresh, double aperture){
	//if (in->nChannels != 1)
	//return 0;
	IplImage* out = cvCreateImage(cvGetSize(in), IPL_DEPTH_8U, 1);
	cvCanny(in, out, lowThresh, highThresh, aperture);
	return(out);
}

int main(){
	//縮小
	IplImage* img = cvLoadImage("D:\\OPENCV實驗\\lena.jpg");
	cvNamedWindow("原圖", CV_WINDOW_AUTOSIZE);
	cvNamedWindow("縮小", CV_WINDOW_AUTOSIZE);
	cvShowImage("原圖", img);
	cvShowImage("縮小", doPyrDown(img));

	//邊緣檢測
	cvNamedWindow("Canny", CV_WINDOW_AUTOSIZE);
	IplImage* out = doCanny(img, 5, 50, 3);
	cvShowImage("Canny", out);
	cvWaitKey(0);

	cvReleaseImage(&img);
	cvReleaseImage(&out);
	cvDestroyAllWindows();
	return 0;
}

結果：