example 10 1,2,4 and new image faces.png

example_10-01.cpp

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+//Example 10-1. Using cv::threshold() to sum three channels of an image
+
+#include <opencv2/opencv.hpp>
+#include <iostream>
+
+using namespace std;
+
+void sum_rgb( const cv::Mat& src, cv::Mat& dst ) {
+
+	// Split image onto the color planes.
+	//
+	vector< cv::Mat> planes;
+	cv::split(src, planes);
+	cv::Mat b = planes[0], g = planes[1], r = planes[2], s;
+
+	// Add equally weighted rgb values.
+	//
+	cv::addWeighted( r, 1./3., g, 1./3., 0.0, s );
+	cv::addWeighted( s, 1., b, 1./3., 0.0, s );
+
+	// Truncate values above 100.
+	//
+	cv::threshold( s, dst, 100, 100, cv::THRESH_TRUNC );
+}
+
+void help() {
+	cout << "Call: ./example_10-03 ../faces.jpg" << endl;
+	cout << "Shows use of alpha blending (addWeighted) and threshold" << endl;
+}
+
+int main(int argc, char** argv) {
+	help();
+	if(argc < 2) { cout << "specify input image" << endl; return -1; }
+
+	// Load the image from the given file name.
+	//
+	cv::Mat src = cv::imread( argv[1] ), dst;
+	if( src.empty() ) { cout << "can not load " << argv[1] << endl; return -1; }
+	sum_rgb( src, dst);
+
+	// Create a named window with the name of the file and
+	// show the image in the window
+	//
+	cv::imshow( argv[1], dst );
+
+	// Idle until the user hits any key.
+	//
+	cv::waitKey(0);
+	return 0;
+}

example_10-02.cpp

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+// Example 10-2. Alternative method to combine and threshold image planes
+
+#include <opencv2/opencv.hpp>
+#include <iostream>
+
+using namespace std;
+
+void sum_rgb( const cv::Mat& src, cv::Mat& dst ) {
+
+	// Split image onto the color planes.
+	//
+	vector<cv::Mat> planes;
+	cv::split(src, planes);
+	cv::Mat b = planes[0], g = planes[1], r = planes[2];
+
+	// Accumulate separate planes, combine and threshold.
+	//
+	cv::Mat s = cv::Mat::zeros(b.size(), CV_32F);
+	cv::accumulate(b, s);
+	cv::accumulate(g, s);
+	cv::accumulate(r, s);
+
+	// Truncate values above 100 and rescale into dst.
+	//
+	cv::threshold( s, s, 100, 100, cv::THRESH_TRUNC );
+	s.convertTo(dst, b.type());
+}
+
+void help() {
+	cout << "Call: ./example_10-02 ../faces.jpg" << endl;
+	cout << "Shows an alternative use of alpha blending and threshold" << endl;
+}
+
+int main(int argc, char** argv) {
+	help();
+	if(argc < 2) { cout << "specify input image" << endl; return -1; }
+
+	// Load the image from the given file name.
+	//
+	cv::Mat src = cv::imread( argv[1] ), dst;
+	if( src.empty() ) { cout << "can not load " << argv[1] << endl; return -1; }
+	sum_rgb( src, dst);
+
+	// Create a named window with the name of the file and
+	// show the image in the window
+	//
+	cv::imshow( argv[1], dst );
+
+	// Idle until the user hits any key.
+	//
+	cv::waitKey(0);
+	return 0;
+}

example_10-03.cpp

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+// Example 10-3. Threshold versus adaptive threshold
+#include <opencv2/opencv.hpp>
+#include <iostream>
+#include <cstdlib>
+using namespace std;
+
+int main( int argc, char** argv )
+{
+	if(argc != 7) { cout <<
+	"Usage: " <<argv[0] <<" fixed_threshold invert(0=off|1=on) "
+	"adaptive_type(0=mean|1=gaussian) block_size offset image\n"
+	"Example: " <<argv[0] <<" 100 1 0 15 10 ../faces.png\n"; return -1; }
+
+	// Process command line arguments
+	//
+	double fixed_threshold = (double)atof(argv[1]);
+	int threshold_type = atoi(argv[2]) ? cv::THRESH_BINARY : cv::THRESH_BINARY_INV;
+	int adaptive_method = atoi(argv[3]) ? cv::ADAPTIVE_THRESH_MEAN_C
+	: cv::ADAPTIVE_THRESH_GAUSSIAN_C;
+	int block_size = atoi(argv[4]);
+	double offset = (double)atof(argv[5]);
+	cv::Mat Igray = cv::imread(argv[6], cv::IMREAD_GRAYSCALE);
+
+	// Read in gray image.
+	//
+	if( Igray.empty() ){ cout << "Can not load " << argv[6] << endl; return -1; }
+
+	// Declare the output images.
+	//
+	cv::Mat It, Iat;
+
+	// Thresholds.
+	//
+	cv::threshold(
+		Igray,
+		It,
+		fixed_threshold,
+		255,
+		threshold_type);
+	cv::adaptiveThreshold(
+		Igray,
+		Iat,
+		255,
+		adaptive_method,
+		threshold_type,
+		block_size,
+		offset
+		);
+
+	// Show the results.
+	//
+	cv::imshow("Raw",Igray);
+	cv::imshow("Threshold",It);
+	cv::imshow("Adaptive Threshold",Iat);
+	cv::waitKey(0);
+	return 0;
+}