Jawaher Khemakhem's profile - activity

I am trying to collect a set of pixels between two pixels:start and end point from a skeleton image . So the idea is : I start on a position in the image. I put that position in a list. Then in a loop,

• I get and remove the point at the beginning of the list and make it black in the current image so it won't be added again.
• I put that point in another list (this is the list that you want).I look at every point around the position and if it is not black, add it to the beginning of the list.

Then start the loop again.

I have develop a piece of code but the loop ends after adding four or five pixels ,before arriving to the end point

 vector<Point> traceLine(Mat img , Point peak)

  {

   vector<Point> vect1;
   vector<Point> vect2;
   vect1.push_back(peak);
        while(vect1.size() != 0)
          {
            Point p=vect1[0];
            img.at<uchar>(p.x,p.y)=0;
            vect1.erase(vect1.begin());
            //cout<<vect1[1];

            vect2.push_back(p);
             vector<Point> vectN;
            vectN=search8Neighbor(img,p);
            cout<<vectN.size()<<endl;
            if(vectN.size()!=0)
                  {
                   for(int i=0;i<vectN.size();i++)

                     vect1.push_back(vectN[i]);

                  }
           }
        return vect2;
 }

I am working on binary image .I have extracted skeleton and the only junction point in the image.

Now I have to extract a list of points :

-from the top-left of the image to the junction point (nearly) in the middle .

-from the junction point to the top- right point in the image .

Any idea to do it ?

See here the documentation please post your code so we can help you .I didn't get the problem .

Here some codes here and here may be it help you .

Have a look at the documentaion

yes I try your code and everything is ok

May be there is a problem with the type of the image that your code reads , have a look here http://opencv.willowgarage.com/documentation/cpp/reading_and_writing_images_and_video.html#cv-imread

please post your code

I didn't understand rpad{i,:}

May be you forget to put waitkey(0);

// display image
cv::namedWindow("Image");
cv::imshow("Image",image);
cv::waitKey(0);
return(0);

Have a look here and here

You can create a folder "projectsOpencv " in your desktop , put the file containing your code "example.cpp" and your image "0.jpg"in the same folder "projectsOpencv" . In this case , char filename[]="0.jpg"; do not modify your code .

There is two methods for calling a file :

• absolute path

C:\projects\myProject\img.png

• non absolute path (relative path)

img.png

Do not forget to put the path between " " .

In the above example, the absolute path contains the full path to the file and not just the file as seen in the non absolute path.

For example , you can put your code source test.cpp and your image in a folder ,name it for example opencv and try the non absolute path .

hey , with pleasure :)

thanks a lot , I feel a little bit confused about Affine Moment Invariants .

Can we calculate it for each pixel ?

I have a question please , we calculate the affine moment invariant for all the image or for each pixel ?

A mat object is 2 D or 3 D array , if we consider that your mat object is 2 D so it is obligatory an array with dimension 2 , you can access to each element in your object mat "im" using for example :

for (int i = 0; i < im.rows; i++)
{
    for (int j = 0; j < im.cols; j++)
    {
        uchar p1 = im.at<uchar>(i, j);// you can access to each element (row/col) 

    }
}

There are two possible cases of multiply for matrices .

Matrix multiplication is where two matrices are multiplied directly. This operation multiplies matrix A of size [a x b] with matrix B of size [b x c] to produce matrix C of size [a x c]. In OpenCV it is achieved using the simple * operator:

C = A * B

Element-wise multiplication is where each pixel (element) in the output matrix is formed by multiplying that pixel (element) in matrix A by its corresponding entry in matrix B. The input matrices should be the same size, and the output will be the same size as well. This is achieved using the mul() function:

output = A.mul(B);

imfft is the name of Mat object ?

To convert from Mat to IplImage :

 Mat mat_img;
IplImage ipl_img = mat_img;

For example to use ipl_img you will write ,

cvNot(&ipl_img ,&ipl_img );

To convert from IplImage to Mat :

IplImage ipl_img;
Mat mat_img(ipl_img );

I have limited a region of interest in a binary image with a rectangle . I have convert this rectangle to a new matrix . now whenever I perform an operation in this matrix there is no change in the original image , but what I want is to have a change in the original image .

     // region of interest 
       Rect roi(maxloc.x,maxloc.y, m2.cols,m2.rows);
    //new matrix  
       Mat image_roi = m1(roi);
    //perform operations 
       bitwise_not(image_roi,image_roi);
      image_roi=choice(image_roi);
     imshow("image",m1);//there is no change in m1

Many thanks , I got the idea how we can build a graph from an image :)

I have a binary image and I am trying to build undirected graph from this image in order to apply minimum spanning tree . My idea is from this paper http://cs.brown.edu/~pff/papers/seg-ijcv.pdf

I have no idea how to build the graph .