Add Java and Python code for the following tutorials:

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

samples/cpp/tutorial_code/ImgProc/BasicLinearTransforms.cpp

@@ -20,29 +20,32 @@ using namespace cv;
  */
 int main( int argc, char** argv )
 {
-    //! [basic-linear-transform-parameters]
-    double alpha = 1.0; /*< Simple contrast control */
-    int beta = 0;       /*< Simple brightness control */
-    //! [basic-linear-transform-parameters]
-
     /// Read image given by user
     //! [basic-linear-transform-load]
-    String imageName("../data/lena.jpg"); // by default
-    if (argc > 1)
+    CommandLineParser parser( argc, argv, "{@input | ../data/lena.jpg | input image}" );
+    Mat image = imread( parser.get<String>( "@input" ) );
+    if( image.empty() )
     {
-        imageName = argv[1];
+      cout << "Could not open or find the image!\n" << endl;
+      cout << "Usage: " << argv[0] << " <Input image>" << endl;
+      return -1;
     }
-    Mat image = imread( imageName );
     //! [basic-linear-transform-load]
+
     //! [basic-linear-transform-output]
     Mat new_image = Mat::zeros( image.size(), image.type() );
     //! [basic-linear-transform-output]
 
+    //! [basic-linear-transform-parameters]
+    double alpha = 1.0; /*< Simple contrast control */
+    int beta = 0;       /*< Simple brightness control */
+
     /// Initialize values
     cout << " Basic Linear Transforms " << endl;
     cout << "-------------------------" << endl;
     cout << "* Enter the alpha value [1.0-3.0]: "; cin >> alpha;
     cout << "* Enter the beta value [0-100]: ";    cin >> beta;
+    //! [basic-linear-transform-parameters]
 
     /// Do the operation new_image(i,j) = alpha*image(i,j) + beta
     /// Instead of these 'for' loops we could have used simply:
@@ -51,19 +54,15 @@ int main( int argc, char** argv )
     //! [basic-linear-transform-operation]
     for( int y = 0; y < image.rows; y++ ) {
         for( int x = 0; x < image.cols; x++ ) {
-            for( int c = 0; c < 3; c++ ) {
+            for( int c = 0; c < image.channels(); c++ ) {
                 new_image.at<Vec3b>(y,x)[c] =
-                  saturate_cast<uchar>( alpha*( image.at<Vec3b>(y,x)[c] ) + beta );
+                  saturate_cast<uchar>( alpha*image.at<Vec3b>(y,x)[c] + beta );
             }
         }
     }
     //! [basic-linear-transform-operation]
 
     //! [basic-linear-transform-display]
-    /// Create Windows
-    namedWindow("Original Image", WINDOW_AUTOSIZE);
-    namedWindow("New Image", WINDOW_AUTOSIZE);
-
     /// Show stuff
     imshow("Original Image", image);
     imshow("New Image", new_image);

samples/cpp/tutorial_code/ImgProc/changing_contrast_brightness_image/changing_contrast_brightness_image.cpp

@@ -3,6 +3,8 @@
 #include "opencv2/highgui.hpp"
 
 // we're NOT "using namespace std;" here, to avoid collisions between the beta variable and std::beta in c++17
+using std::cout;
+using std::endl;
 using namespace cv;
 
 namespace
@@ -19,12 +21,13 @@ void basicLinearTransform(const Mat &img, const double alpha_, const int beta_)
     img.convertTo(res, -1, alpha_, beta_);
 
     hconcat(img, res, img_corrected);
+    imshow("Brightness and contrast adjustments", img_corrected);
 }
 
 void gammaCorrection(const Mat &img, const double gamma_)
 {
     CV_Assert(gamma_ >= 0);
-    //![changing-contrast-brightness-gamma-correction]
+    //! [changing-contrast-brightness-gamma-correction]
     Mat lookUpTable(1, 256, CV_8U);
     uchar* p = lookUpTable.ptr();
     for( int i = 0; i < 256; ++i)
@@ -32,9 +35,10 @@ void gammaCorrection(const Mat &img, const double gamma_)
 
     Mat res = img.clone();
     LUT(img, lookUpTable, res);
-    //![changing-contrast-brightness-gamma-correction]
+    //! [changing-contrast-brightness-gamma-correction]
 
     hconcat(img, res, img_gamma_corrected);
+    imshow("Gamma correction", img_gamma_corrected);
 }
 
 void on_linear_transform_alpha_trackbar(int, void *)
@@ -60,36 +64,32 @@ void on_gamma_correction_trackbar(int, void *)
 
 int main( int argc, char** argv )
 {
-
-    String imageName("../data/lena.jpg"); // by default
-    if (argc > 1)
+    CommandLineParser parser( argc, argv, "{@input | ../data/lena.jpg | input image}" );
+    img_original = imread( parser.get<String>( "@input" ) );
+    if( img_original.empty() )
     {
-        imageName = argv[1];
+      cout << "Could not open or find the image!\n" << endl;
+      cout << "Usage: " << argv[0] << " <Input image>" << endl;
+      return -1;
     }
 
-    img_original = imread( imageName );
     img_corrected = Mat(img_original.rows, img_original.cols*2, img_original.type());
     img_gamma_corrected = Mat(img_original.rows, img_original.cols*2, img_original.type());
 
     hconcat(img_original, img_original, img_corrected);
     hconcat(img_original, img_original, img_gamma_corrected);
 
-    namedWindow("Brightness and contrast adjustments", WINDOW_AUTOSIZE);
-    namedWindow("Gamma correction", WINDOW_AUTOSIZE);
+    namedWindow("Brightness and contrast adjustments");
+    namedWindow("Gamma correction");
 
     createTrackbar("Alpha gain (contrast)", "Brightness and contrast adjustments", &alpha, 500, on_linear_transform_alpha_trackbar);
     createTrackbar("Beta bias (brightness)", "Brightness and contrast adjustments", &beta, 200, on_linear_transform_beta_trackbar);
     createTrackbar("Gamma correction", "Gamma correction", &gamma_cor, 200, on_gamma_correction_trackbar);
 
-    while (true)
-    {
-        imshow("Brightness and contrast adjustments", img_corrected);
-        imshow("Gamma correction", img_gamma_corrected);
+    on_linear_transform_alpha_trackbar(0, 0);
+    on_gamma_correction_trackbar(0, 0);
 
-        int c = waitKey(30);
-        if (c == 27)
-            break;
-    }
+    waitKey();
 
     imwrite("linear_transform_correction.png", img_corrected);
     imwrite("gamma_correction.png", img_gamma_corrected);