Separable kernels from OpenCV

[Victor Kulichkin]

Hello guys,

I am learning OpenCV by the book "OpenCV...." and cannot make one exercise there:

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Separable kernels. Create a 3-by-3 Gaussian kernel using rows [(1/16, 2/16, 1/16), (2/16, 4/16, 2/16), (1/16, 2/16, 1/16)] and with anchor point in the middle.

a. Run this kernel on an image and display the results.

b. Now create two one-dimensional kernels with anchors in the center: one going “across” (1/4, 2/4, 1/4), and one going down (1/4, 2/4, 1/4). Load the same original image and use cvFilter2D() to convolve the image twice, once with the first 1D kernel and once with the second 1D kernel. Describe the results.
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I did three those filters, but they do not change my source image, why, where is my error?

Here is my code:

		IplImage* src = cvLoadImage("4.jpg");
		cvNamedWindow("src", 1);
		cvShowImage("src", src);
		IplImage* rgb[3];
		float L45[]={
			1./16., 2./16., 1./16.,
			2./16., 4./16., 2./16.,
			1./16., 2./16., 1./16.};//  
		CvMat*  rgbMat = cvCreateMat(3, 3, CV_32FC1);
		for (int y = 0; y < 3; y++)
		{
			for (int x = 0; x < 3; x++)
				cvmSet(rgbMat, y, x, L45[y*3 + x]);
		}
		IplImage* dst = cvCreateImage(cvSize(src->width, src->height), src->depth, 3);
		IplImage* dstRGB[3];
		for (int i = 0; i < 3; i++)
		{
			rgb[i] = cvCreateImage(cvSize(src->width, src->height), src->depth, 1);
			dstRGB[i] = cvCreateImage(cvSize(src->width, src->height), src->depth, 1);
		}
		cvSplit(src, rgb[0], rgb[1], rgb[2], NULL);
		for (int i = 0; i < 3; i++)
		{
			cvFilter2D(rgb[i], dstRGB[i], rgbMat);
		}
		cvReleaseMat(&rgbMat);
		cvMerge(dstRGB[0], dstRGB[1], dstRGB[2], NULL, dst);
		cvNamedWindow("dst", 1);
		cvShowImage("dst", dst);
		//across
		float D[] = {1./4., 2./4., 1./4.};
		rgbMat = cvCreateMat(1, 3, CV_32FC1);
		for (int x = 0; x < 3; x++)
			cvmSet(rgbMat, 0, x, D[x]);
		for (int i = 0; i < 3; i++)
		{
			cvZero(dstRGB[i]);
			cvFilter2D(rgb[i], dstRGB[i], rgbMat, cvPoint(1, 0));
		}
		cvReleaseMat(&rgbMat);
		cvZero(dst);
		cvMerge(dstRGB[0], dstRGB[1], dstRGB[2], NULL, dst);
		cvNamedWindow("Across", 1);
		cvShowImage("Across", dst);
		//down
		rgbMat = cvCreateMat(3, 1, CV_32FC1);
		for (int y = 0; y < 3; y++)
			cvmSet(rgbMat, y, 0, D[y]);
		for (int i = 0; i < 3; i++)
		{
			cvZero(dstRGB[i]);
			cvFilter2D(rgb[i], dstRGB[i], rgbMat, cvPoint(0, 1));
		}
		cvReleaseMat(&rgbMat);
		cvZero(dst);
		cvMerge(dstRGB[0], dstRGB[1], dstRGB[2], NULL, dst);
		cvNamedWindow("Down", 1);
		cvShowImage("Down", dst);
		cvReleaseImage(&dst);
		for (int i = 0; i < 3; i++)
		{
			cvReleaseImage(&rgb[i]);
			cvReleaseImage(&dstRGB[i]);
		}
		cvWaitKey(0);
		cvReleaseImage(&src);
		cvDestroyWindow("src");
		cvDestroyWindow("dst");
		cvDestroyWindow("Across");
		cvDestroyWindow("Down");