harris detector in callback

edit

I have been trying to implement Harris corner detector. But the result are pretty skewed. There is always some symmetry in the detected corners as shown in the image below which definitely is not true.(right image is grayscaled image...why does it happens as such..must be 3 different channels joined together..

My callback portion looks like:

void imageCb(const sensor_msgs::ImageConstPtr& image)
{
    cv_bridge::CvImagePtr cv_ptr;

    try                         
    {
        cv_ptr = cv_bridge::toCvCopy(image, enc::BGR8); 

    }
    catch (cv_bridge::Exception& e)
    {
        ROS_ERROR("Conversion error: %s", e.what());
        return;
    }

    cv::Mat image_gray, image_corner, image_norm, image_scaled;

    cv::cvtColor(cv_ptr->image, image_gray, CV_BGR2GRAY); 
    cv::cornerHarris(image_gray, image_corner,blockSize, apertureSize, k, cv::BORDER_DEFAULT);    


    cv::normalize(image_corner, image_norm, 0, 255, cv::NORM_MINMAX, CV_8UC1, cv::Mat());   
    cv::convertScaleAbs (image_norm, image_scaled); //scaled



    //Drawing circles around corner

    for(int j=0; j<cv_ptr->image.rows ; j++) //norm
    {
        for(int i = 0; i<cv_ptr->image.cols; i++)
        {
            if((int) image_scaled.at<float>(j,i) > thresh)
            {
                cv::circle(cv_ptr->image, cv::Point(i, j),2,CV_RGB(255,0,0)); //scaled
            }
        }
    }

    pub_.publish(cv_ptr->toImageMsg());     

}

I think it is basically due to the RGB channels but there are four similar clusters of corner which confused me. most of the code is directly taken from opencv example of harris detector. Any help is deeply appreciated. Thanks.