Start Developing OpenCV Applications Immediately Using the BDTI Quick-Start OpenCV Kit (Article)
Posted by grouby 1 month ago
Eric,
Thank you for this great Quick-Start OpenCV Kit!
Being more used to the Windows OS myself, this definitely got me up and running very rapidly!
In the CannyEdgeDetection example code, you have calls to the Gaussian/Sobel/cartToPolar OpenCV functions, in addition to the Canny function call.
I assume that the Canny function is also doing these operations.
Can you confirm that this is the case, and that you have called these functions redundantly for illustrative purposes?
Regards,
Mario Bergeron
Posted by Eric Gregori 1 years ago
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Mario,
The additional code is required to display the Sobel X,Y, angle, and magnitude outputs.
The OpenCV Canny function does not expose this data.
For Figure 14 (and the demo) I want to show the user what this intermediate data looks like.
The following lines are NOT required for Canny operation:
Sobel( blurred, grad_x, CV_32F, 1, 0, Ksize, 1, 0, BORDER_DEFAULT );
Sobel( blurred, grad_y, CV_32F, 0, 1, Ksize, 1, 0, BORDER_DEFAULT );
cartToPolar( grad_x, grad_y, magnitude, angle, true );
threshold( magnitude, magnitude, LowThres, 0, THRESH_TOZERO );
threshold( grad_x, grad_x, LowThres, 0, THRESH_TOZERO );
threshold( grad_y, grad_y, LowThres, 0, THRESH_TOZERO );
Mat mask, MaskedAngle;
Mat bmask = Mat::zeros(magnitude.rows, magnitude.cols, CV_8U );
threshold( magnitude, mask, LowThres, 1, THRESH_BINARY );
mask.convertTo( bmask, CV_8U );
angle.copyTo( MaskedAngle, bmask );