doc: add new tutorial "Out of focus deblur filter"

In this tutorial you will learn:
- what is a degradation image model
- what is a PSF of an out-of-focus image
- how to restore a blurred image
- what is the Wiener filter

samples/cpp/tutorial_code/ImgProc/out_of_focus_deblur_filter/out_of_focus_deblur_filter.cpp

@@ -0,0 +1,149 @@
+/**
+* @brief You will learn how to recover an out-of-focus image by Wiener filter
+* @author Karpushin Vladislav, karpushin@ngs.ru, https://github.com/VladKarpushin
+*/
+#include <iostream>
+#include "opencv2/imgproc.hpp"
+#include "opencv2/imgcodecs.hpp"
+
+using namespace cv;
+using namespace std;
+
+void help();
+void calcPSF(Mat& outputImg, Size filterSize, int R);
+void fftshift(const Mat& inputImg, Mat& outputImg);
+void filter2DFreq(const Mat& inputImg, Mat& outputImg, const Mat& H);
+void calcWnrFilter(const Mat& input_h_PSF, Mat& output_G, double nsr);
+
+const String keys =
+"{help h usage ? |             | print this message   }"
+"{image          |original.JPG | input image name     }"
+"{R              |53           | radius               }"
+"{SNR            |5200         | signal to noise ratio}"
+;
+
+int main(int argc, char *argv[])
+{
+    help();
+    CommandLineParser parser(argc, argv, keys);
+    if (parser.has("help"))
+    {
+        parser.printMessage();
+        return 0;
+    }
+
+    int R = parser.get<int>("R");
+    int snr = parser.get<int>("SNR");
+    string strInFileName = parser.get<String>("image");
+
+    if (!parser.check())
+    {
+        parser.printErrors();
+        return 0;
+    }
+
+    Mat imgIn;
+    imgIn = imread(strInFileName, IMREAD_GRAYSCALE);
+    if (imgIn.empty()) //check whether the image is loaded or not
+    {
+        cout << "ERROR : Image cannot be loaded..!!" << endl;
+        return -1;
+    }
+
+    Mat imgOut;
+
+//! [main]
+    // it needs to process even image only
+    Rect roi = Rect(0, 0, imgIn.cols & -2, imgIn.rows & -2);
+
+    //Hw calculation (start)
+    Mat Hw, h;
+    calcPSF(h, roi.size(), R);
+    calcWnrFilter(h, Hw, 1.0 / double(snr));
+    //Hw calculation (stop)
+
+    // filtering (start)
+    filter2DFreq(imgIn(roi), imgOut, Hw);
+    // filtering (stop)
+//! [main]
+
+    imgOut.convertTo(imgOut, CV_8U);
+    normalize(imgOut, imgOut, 0, 255, NORM_MINMAX);
+    imwrite("result.jpg", imgOut);
+    return 0;
+}
+
+void help()
+{
+    cout << "2018-07-12" << endl;
+    cout << "DeBlur_v8" << endl;
+    cout << "You will learn how to recover an out-of-focus image by Wiener filter" << endl;
+}
+
+//! [calcPSF]
+void calcPSF(Mat& outputImg, Size filterSize, int R)
+{
+    Mat h(filterSize, CV_32F, Scalar(0));
+    Point point(filterSize.width / 2, filterSize.height / 2);
+    circle(h, point, R, 255, -1, 8);
+    Scalar summa = sum(h);
+    outputImg = h / summa[0];
+}
+//! [calcPSF]
+
+//! [fftshift]
+void fftshift(const Mat& inputImg, Mat& outputImg)
+{
+    outputImg = inputImg.clone();
+    int cx = outputImg.cols / 2;
+    int cy = outputImg.rows / 2;
+    Mat q0(outputImg, Rect(0, 0, cx, cy));
+    Mat q1(outputImg, Rect(cx, 0, cx, cy));
+    Mat q2(outputImg, Rect(0, cy, cx, cy));
+    Mat q3(outputImg, Rect(cx, cy, cx, cy));
+    Mat tmp;
+    q0.copyTo(tmp);
+    q3.copyTo(q0);
+    tmp.copyTo(q3);
+    q1.copyTo(tmp);
+    q2.copyTo(q1);
+    tmp.copyTo(q2);
+}
+//! [fftshift]
+
+//! [filter2DFreq]
+void filter2DFreq(const Mat& inputImg, Mat& outputImg, const Mat& H)
+{
+    Mat planes[2] = { Mat_<float>(inputImg.clone()), Mat::zeros(inputImg.size(), CV_32F) };
+    Mat complexI;
+    merge(planes, 2, complexI);
+    dft(complexI, complexI, DFT_SCALE);
+
+    Mat planesH[2] = { Mat_<float>(H.clone()), Mat::zeros(H.size(), CV_32F) };
+    Mat complexH;
+    merge(planesH, 2, complexH);
+    Mat complexIH;
+    mulSpectrums(complexI, complexH, complexIH, 0);
+
+    idft(complexIH, complexIH);
+    split(complexIH, planes);
+    outputImg = planes[0];
+}
+//! [filter2DFreq]
+
+//! [calcWnrFilter]
+void calcWnrFilter(const Mat& input_h_PSF, Mat& output_G, double nsr)
+{
+    Mat h_PSF_shifted;
+    fftshift(input_h_PSF, h_PSF_shifted);
+    Mat planes[2] = { Mat_<float>(h_PSF_shifted.clone()), Mat::zeros(h_PSF_shifted.size(), CV_32F) };
+    Mat complexI;
+    merge(planes, 2, complexI);
+    dft(complexI, complexI);
+    split(complexI, planes);
+    Mat denom;
+    pow(abs(planes[0]), 2, denom);
+    denom += nsr;
+    divide(planes[0], denom, output_G);
+}
+//! [calcWnrFilter]