Added examples

examples/colors/04_Threshold.cpp

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+#include <iostream>
+#include <opencv2/highgui/highgui.hpp>
+#include <opencv2/imgproc/imgproc.hpp>
+
+using namespace cv;
+using namespace std;
+
+int main( int argc, char** argv ) {
+
+	// Create matrix from image
+	Mat imageSrc = imread("lena1.png", CV_LOAD_IMAGE_COLOR);
+
+	// Create windows
+	namedWindow("Source", WINDOW_AUTOSIZE);
+	namedWindow("Destination", WINDOW_AUTOSIZE);
+
+	int val1 = 0;
+	int val2 = 0;
+
+	createTrackbar("Val1", "Destination", &val1, 255);
+	createTrackbar("Val2", "Destination", &val2, 255);
+
+	// Keep updating
+	while(true) {
+
+		// Destination matrix
+		Mat imageDest;
+
+		// Convert to grayscale
+		cvtColor(imageSrc, imageDest, CV_BGR2GRAY);
+
+		// Apply threshold
+		threshold(imageDest, imageDest, 150, 255, CV_THRESH_BINARY);
+
+		// Show images
+		imshow("Source", imageSrc);
+		imshow("Destination", imageDest);
+
+		// Wait forever
+		waitKey(50);
+	}
+
+	return 0;
+}
+