Calculating MyHistogram

asked 2017-03-15 06:10:24 -0600

GennyLimite gravatar image

Hi all,

I'm trying to do a version of mine to calcolute an Histogram.

I think that the logic is this, but i don't know why it's going in segmentation fault.

Can anyone help me?

    //My Hist
    int Occorrenze[255];
    for(int i=0;i<255;i++)
            Occorrenze[i]=0;

    for(int i=0;i<src.rows;i++)
    {
            for(int j=0;j<src.cols;j++)
            {
                    Occorrenze[src.at<uchar>(i,j)]++;
            }
    }
    Mat MyHist(255,255,CV_8U);
    for(int colonna=0;colonna<255;colonna++)
    {
            int numero=0;
            int flag=0;
            while(numero != Occorrenze[colonna] && flag==0)
            {
                    MyHist.at<uchar>((255-numero),colonna)=255;
                    numero++;
                    if(numero==255)
                            flag=1;
            }
    }
    namedWindow("Hist",WINDOW_AUTOSIZE);
    imshow("Hist",MyHist);

thank u so much

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Comments

You should use an array of size=256 as values go from 0 to 255 (included).

I guess your segmentation fault comes from this line:

MyHist.at<uchar>((255-numero),colonna)=255;

When numero==0, 255-numero==255 but you have declared: Mat MyHist(255,255,CV_8U);.

If you are on Linux, gdb is a pretty useful tool for debugging.

Eduardo gravatar imageEduardo ( 2017-03-15 07:09:57 -0600 )edit

Thank u so much Eduardo.

I changed the size and it is going well. Obvious the result isn't the same of the opencv function "calchist but the trand i think is similar.

GennyLimite gravatar imageGennyLimite ( 2017-03-15 07:31:43 -0600 )edit
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