initial commit

samples/cpp/demhist.cpp

@@ -0,0 +1,94 @@
+#include "opencv2/core/utility.hpp"
+#include "opencv2/imgproc.hpp"
+#include "opencv2/imgcodecs.hpp"
+#include "opencv2/highgui.hpp"
+
+#include <iostream>
+
+using namespace cv;
+using namespace std;
+
+int _brightness = 100;
+int _contrast = 100;
+
+Mat image;
+
+/* brightness/contrast callback function */
+static void updateBrightnessContrast( int /*arg*/, void* )
+{
+    int histSize = 64;
+    int brightness = _brightness - 100;
+    int contrast = _contrast - 100;
+
+    /*
+     * The algorithm is by Werner D. Streidt
+     * (http://visca.com/ffactory/archives/5-99/msg00021.html)
+     */
+    double a, b;
+    if( contrast > 0 )
+    {
+        double delta = 127.*contrast/100;
+        a = 255./(255. - delta*2);
+        b = a*(brightness - delta);
+    }
+    else
+    {
+        double delta = -128.*contrast/100;
+        a = (256.-delta*2)/255.;
+        b = a*brightness + delta;
+    }
+
+    Mat dst, hist;
+    image.convertTo(dst, CV_8U, a, b);
+    imshow("image", dst);
+
+    calcHist(&dst, 1, 0, Mat(), hist, 1, &histSize, 0);
+    Mat histImage = Mat::ones(200, 320, CV_8U)*255;
+
+    normalize(hist, hist, 0, histImage.rows, NORM_MINMAX, CV_32F);
+
+    histImage = Scalar::all(255);
+    int binW = cvRound((double)histImage.cols/histSize);
+
+    for( int i = 0; i < histSize; i++ )
+        rectangle( histImage, Point(i*binW, histImage.rows),
+                   Point((i+1)*binW, histImage.rows - cvRound(hist.at<float>(i))),
+                   Scalar::all(0), -1, 8, 0 );
+    imshow("histogram", histImage);
+}
+
+const char* keys =
+{
+    "{help h||}{@image|baboon.jpg|input image file}"
+};
+
+int main( int argc, const char** argv )
+{
+    CommandLineParser parser(argc, argv, keys);
+    parser.about("\nThis program demonstrates the use of calcHist() -- histogram creation.\n");
+    if (parser.has("help"))
+    {
+        parser.printMessage();
+        return 0;
+    }
+    string inputImage = parser.get<string>(0);
+
+    // Load the source image. HighGUI use.
+    image = imread(samples::findFile(inputImage), IMREAD_GRAYSCALE);
+    if(image.empty())
+    {
+        std::cerr << "Cannot read image file: " << inputImage << std::endl;
+        return -1;
+    }
+
+    namedWindow("image", 0);
+    namedWindow("histogram", 0);
+
+    createTrackbar("brightness", "image", &_brightness, 200, updateBrightnessContrast);
+    createTrackbar("contrast", "image", &_contrast, 200, updateBrightnessContrast);
+
+    updateBrightnessContrast(0, 0);
+    waitKey();
+
+    return 0;
+}