Comments on: Canny Edge Detection Auto Thresholding

By: Gustav

Gustav — Wed, 15 Dec 2010 23:07:30 +0000

fogot to add
Ipp32f* l = new Ipp32f[nLevel+1];

By: Gustav

Gustav — Wed, 15 Dec 2010 23:04:01 +0000

Your code will miss the values in the last bin i.e (maxVal-stepVal)->maxVal. your array only assigns bins between minVal and minVal+stepVal*(nLevel-1).
If you had 20 bins, a min of 20 a max of 220 you would have a step of 10 which would give you a max bin value of (20+10*(19))=210 so your histogram would never have any values for the bin between 210 and 220. The ippiHistogramRange_32f_C1R function requires the max value to be the last pLevels array.

try

unsigned int* bins = new unsigned int[nLevel];

for (unsigned int i = 0; i <= nLevel; i++)
{
l[i] = minVal + stepVal * i;
}

By: lily

lily — Tue, 09 Nov 2010 14:15:11 +0000

this code should be pasted in visual studio and also run opencv on ur sys to run the code. contact me on my e-mail if u hve any doubts, i did as my proj this sem so i can help u..

By: lily

lily — Tue, 09 Nov 2010 14:10:26 +0000

#include”stdafx.h”
#include “cv.h”
#include “cxcore.h”
#include”cvaux.h”
#include “highgui.h”
int main()
{
IplImage* newImg = NULL;
IplImage* grayImg = NULL;
IplImage* contourImg = NULL;
IplImage* cannyImg;
//parameters for the contour detection
CvMemStorage * storage = cvCreateMemStorage(0);
CvSeq * contour = 0;
int mode = CV_RETR_EXTERNAL;
mode = CV_RETR_CCOMP; //detect both outside and inside contour
cvNamedWindow(“src”, 1);
cvNamedWindow(“contour”,1);
//load original image
newImg = cvLoadImage(“C:/Documents and Settings/welcome/Desktop/tom2.jpg”,1);
//create a single channel 1 byte image (i.e. gray-level image)
grayImg = cvCreateImage( cvSize(newImg->width, newImg->height), IPL_DEPTH_8U, 1 );
//convert original color image (3 channel rgb color image) to gray-level image
cvCvtColor( newImg, grayImg, CV_BGR2GRAY );
cvShowImage( “src”, newImg );

cannyImg = cvCreateImage(cvGetSize(newImg), IPL_DEPTH_8U, 1);
// canny edge detection
cvCanny(grayImg, cannyImg, 50, 150, 3);
cvNamedWindow(“src”, 1);
cvNamedWindow(“canny”,1);
cvShowImage( “src”, newImg );
cvShowImage( “canny”, cannyImg );
cvReleaseImage( &newImg ); cvReleaseImage( &grayImg ); cvReleaseImage( &contourImg );
cvReleaseMemStorage(&storage);
return 0;
}

By: mehdi

mehdi — Sun, 25 Jul 2010 14:41:42 +0000

i need canny edge detection in vb(source code )
please help me
tnx

By: rob

rob — Mon, 21 Dec 2009 17:03:23 +0000

is there any vb6 code for canny autothresholding? tnx!