Add Java and Python code for the following tutorials:

- Changing the contrast and brightness of an image!
      - Operations with images

samples/cpp/tutorial_code/core/mat_operations/mat_operations.cpp

@@ -0,0 +1,180 @@
+/*  Snippet code for Operations with images tutorial (not intended to be run but should built successfully) */
+
+#include "opencv2/core.hpp"
+#include "opencv2/core/core_c.h"
+#include "opencv2/imgcodecs.hpp"
+#include "opencv2/imgproc.hpp"
+#include "opencv2/highgui.hpp"
+#include <iostream>
+
+using namespace cv;
+using namespace std;
+
+int main(int,char**)
+{
+    std::string filename = "";
+    // Input/Output
+    {
+        //! [Load an image from a file]
+        Mat img = imread(filename);
+        //! [Load an image from a file]
+        CV_UNUSED(img);
+    }
+    {
+        //! [Load an image from a file in grayscale]
+        Mat img = imread(filename, IMREAD_GRAYSCALE);
+        //! [Load an image from a file in grayscale]
+        CV_UNUSED(img);
+    }
+    {
+        Mat img(4,4,CV_8U);
+        //! [Save image]
+        imwrite(filename, img);
+        //! [Save image]
+    }
+    // Accessing pixel intensity values
+    {
+        Mat img(4,4,CV_8U);
+        int y = 0, x = 0;
+        {
+            //! [Pixel access 1]
+            Scalar intensity = img.at<uchar>(y, x);
+            //! [Pixel access 1]
+            CV_UNUSED(intensity);
+        }
+        {
+            //! [Pixel access 2]
+            Scalar intensity = img.at<uchar>(Point(x, y));
+            //! [Pixel access 2]
+            CV_UNUSED(intensity);
+        }
+        {
+            //! [Pixel access 3]
+            Vec3b intensity = img.at<Vec3b>(y, x);
+            uchar blue = intensity.val[0];
+            uchar green = intensity.val[1];
+            uchar red = intensity.val[2];
+            //! [Pixel access 3]
+            CV_UNUSED(blue);
+            CV_UNUSED(green);
+            CV_UNUSED(red);
+        }
+        {
+            //! [Pixel access 4]
+            Vec3f intensity = img.at<Vec3f>(y, x);
+            float blue = intensity.val[0];
+            float green = intensity.val[1];
+            float red = intensity.val[2];
+            //! [Pixel access 4]
+            CV_UNUSED(blue);
+            CV_UNUSED(green);
+            CV_UNUSED(red);
+        }
+        {
+            //! [Pixel access 5]
+            img.at<uchar>(y, x) = 128;
+            //! [Pixel access 5]
+        }
+        {
+            int i = 0;
+            //! [Mat from points vector]
+            vector<Point2f> points;
+            //... fill the array
+            Mat pointsMat = Mat(points);
+            //! [Mat from points vector]
+
+            //! [Point access]
+            Point2f point = pointsMat.at<Point2f>(i, 0);
+            //! [Point access]
+            CV_UNUSED(point);
+        }
+    }
+    // Memory management and reference counting
+    {
+        //! [Reference counting 1]
+        std::vector<Point3f> points;
+        // .. fill the array
+        Mat pointsMat = Mat(points).reshape(1);
+        //! [Reference counting 1]
+        CV_UNUSED(pointsMat);
+    }
+    {
+        //! [Reference counting 2]
+        Mat img = imread("image.jpg");
+        Mat img1 = img.clone();
+        //! [Reference counting 2]
+        CV_UNUSED(img1);
+    }
+    {
+        //! [Reference counting 3]
+        Mat img = imread("image.jpg");
+        Mat sobelx;
+        Sobel(img, sobelx, CV_32F, 1, 0);
+        //! [Reference counting 3]
+    }
+    // Primitive operations
+    {
+        Mat img;
+        {
+            //! [Set image to black]
+            img = Scalar(0);
+            //! [Set image to black]
+        }
+        {
+            //! [Select ROI]
+            Rect r(10, 10, 100, 100);
+            Mat smallImg = img(r);
+            //! [Select ROI]
+            CV_UNUSED(smallImg);
+        }
+    }
+    {
+        //! [C-API conversion]
+        Mat img = imread("image.jpg");
+        IplImage img1 = img;
+        CvMat m = img;
+        //! [C-API conversion]
+        CV_UNUSED(img1);
+        CV_UNUSED(m);
+    }
+    {
+        //! [BGR to Gray]
+        Mat img = imread("image.jpg"); // loading a 8UC3 image
+        Mat grey;
+        cvtColor(img, grey, COLOR_BGR2GRAY);
+        //! [BGR to Gray]
+    }
+    {
+        Mat dst, src;
+        //! [Convert to CV_32F]
+        src.convertTo(dst, CV_32F);
+        //! [Convert to CV_32F]
+    }
+    // Visualizing images
+    {
+        //! [imshow 1]
+        Mat img = imread("image.jpg");
+        namedWindow("image", WINDOW_AUTOSIZE);
+        imshow("image", img);
+        waitKey();
+        //! [imshow 1]
+    }
+    {
+        //! [imshow 2]
+        Mat img = imread("image.jpg");
+        Mat grey;
+        cvtColor(img, grey, COLOR_BGR2GRAY);
+        Mat sobelx;
+        Sobel(grey, sobelx, CV_32F, 1, 0);
+        double minVal, maxVal;
+        minMaxLoc(sobelx, &minVal, &maxVal); //find minimum and maximum intensities
+        Mat draw;
+        sobelx.convertTo(draw, CV_8U, 255.0/(maxVal - minVal), -minVal * 255.0/(maxVal - minVal));
+        namedWindow("image", WINDOW_AUTOSIZE);
+        imshow("image", draw);
+        waitKey();
+        //! [imshow 2]
+    }
+
+    return 0;
+}