อบรมสอน Visual studio และประมวลผลภาพด้วย Open CV ตอนที่ 1

 example 1 : open image file
#include <opencv2/opencv.hpp>
using namespace cv;

int main()
{
	Mat image;
	image = imread("Lena.png");
	namedWindow("My image", CV_WINDOW_NORMAL); // CV_WINDOW_AUTOSIZE
	imshow("My image", image);
	waitKey(0);
	return 0;
}
 ========================================================

 example 2 : stream webcam
#include <opencv2/opencv.hpp>
using namespace cv;
int main()
{
	Mat image;
	VideoCapture capture;
	capture.open(0);
	namedWindow("My image", CV_WINDOW_NORMAL);
	while (1)
	{
		capture >> image;
		imshow("My image", image);

		char c = waitKey(50); //wait for 50 milliseconds and 
		if (c == 27) //exit the loop if user press "Esc" key
			break;
	}
	return 0;
}
 ========================================================

// example 3 : split image
#include <opencv2/opencv.hpp>
using namespace cv;
int main()
{
	Mat image;	// color image
	image = imread("rgb.png");

	namedWindow("Original Image", CV_WINDOW_NORMAL); //CV_WINDOW_AUTOSIZE
	namedWindow("Blue", CV_WINDOW_NORMAL);
	namedWindow("Green", CV_WINDOW_NORMAL);
	namedWindow("Red", CV_WINDOW_NORMAL);

	imshow("Original Image", image);

	Mat rgbchannel[3];
	split(image, rgbchannel);
	imshow("Red", rgbchannel[2]);
	imshow("Green", rgbchannel[1]);
	imshow("Blue", rgbchannel[0]);
	waitKey(0);
	return 0;
}

// example 4 : put text into image
#include <opencv2/opencv.hpp>
using namespace cv;
int main()
{
	Mat image;
	image = imread("stopsign.jpg");
	namedWindow("My image", CV_WINDOW_NORMAL); // CV_WINDOW_AUTOSIZE
	putText(image, //target image
			"Hello", //text
			Point(10, image.rows / 2), //top-left position
			FONT_HERSHEY_DUPLEX,
			1.0,
			CV_RGB(255, 0, 0), //font color
			2);
	imshow("My image", image);
	waitKey(0);
	return 0;
}

// example 5 : draw a rectangle into image
#include <opencv2/opencv.hpp>
using namespace cv;
int main()
{
	Mat image;
	image = imread("stopsign.jpg");
	namedWindow("My image", CV_WINDOW_NORMAL); // CV_WINDOW_AUTOSIZE
	int x = 20;
	int y = 20;
	int width = 100;
	int height = 200;
	Point pt1(x, y); // top left corner
	Point pt2(x + width, y + height); // bottom right corner.
	rectangle(image, pt1, pt2, Scalar(0, 255, 0), 3);
	imshow("My image", image);
	waitKey(0);
	return 0;
}