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I couldn't use the histogram functions descriped in openCV doc , because it try to find color histogram , and the question try to find projection in on X-axis and Y-axis for black and white image. i used the following code the find vertical and herozontal projection.

//2-find x ,y projections (horizontal projection)
    Mat horizontal(ROIimg.cols,1,CV_32S);//horizontal histogram
    horizontal = Scalar::all(0);
    Mat vertical(ROIimg.rows,1,CV_32S);//vertical histogram
    vertical = Scalar::all(0);
    for(int i=0;i<ROIimg.cols;i++)
    {
        horizontal.at<int>(i,0)=countNonZero(ROIimg(Rect(i,0,1,ROIimg.rows)));
    }
    for(int i=0;i<ROIimg.rows;i++)
    {
        vertical.at<int>(i,0) = countNonZero(ROIimg(Rect(0,i,ROIimg.cols,1)));
    }

where ROIimg is balck and white