C / C++ / MFC

// I create the pDC, memDC and the compatible device/bitmap
CDC* pDC = m_Picture.GetDC();  // m_picture is a member CStatic element in the main CDialog class 
CDC memDC;
CBitmap bmp;
memDC.CreateCompatibleDC(pDC);
bmp.CreateCompatibleBitmap(pDC, PicW, PicH); //  PicW, PicH are the width and height of the associated CRect member object in the class  

// After that, I get the points to plot in order to write them to my memDC

//then, I copy the memDC to the device and delete the memDC, release the pDC 
pDC->StretchBlt(0, 0, PicW, PicH, &memDC, 0, 0, PicW, PicH, SRCCOPY);
bmp.DeleteObject();
memDC.DeleteDC();
ReleaseDC(pDC);

#include <opencv2/highgui/highgui.hpp>
  #include <opencv2/core/core.hpp>
  #include <opencv2/core/mat.hpp>
  #include <opencv2/imgproc/imgproc.hpp>
  #include<iostream>
  #include<math.h>
  
using namespace std;
using namespace cv;
float soft_tresholding(Mat src, float threshold)
{


int height=src.rows;
int width=src.cols;
 for(int y=0; y < height; y++) 
    {
        for(int x=0; x < width; x++) 
        {
            if (src(y*width+x) > threshold)
                src(y*width+x) = src(y*width+x) - threshold;
            else if (src(y*width+x) < -threshold)
                src(y*width+x) = src(y*width+x) + threshold;
            else
                src(y*width+x) = 0;
        }
    }
}
 int main()
{
system("clear");

 Mat src=imread("/home/jamal/Bureau/lena.jpg",0);
Mat dst;
float threshold;
dst=soft_thresholding(src,threshold);	

	namedWindow("Picture", CV_WINDOW_AUTOSIZE); 
	   imshow("Picture", src); 
          namedWindow("picf", CV_WINDOW_AUTOSIZE); 
	   imshow("Picf", dst); 
	   waitKey(); 
        
	return 0;
}