อบรมสอน Visual studio และประมวลผลภาพด้วย Open CV ตอนที่ 2

ฮิสโตแกรม

// example : histogram plot
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;
int main(int argc, char** argv)
{
	//Mat src = imread("histogram.png", IMREAD_COLOR);
	Mat src = imread("Lena.png", IMREAD_COLOR);
	//Mat src = imread("rgb.png", IMREAD_COLOR);
	if (src.empty())
	{
		return EXIT_FAILURE;
	}
	vector<Mat> bgr_planes;
	split(src, bgr_planes);
	int histSize = 256;
	float range[] = { 0, 256 }; //the upper boundary is exclusive
	const float* histRange = { range };
	bool uniform = true, accumulate = false;
	Mat b_hist, g_hist, r_hist;
	calcHist(&bgr_planes[0], 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate);
	calcHist(&bgr_planes[1], 1, 0, Mat(), g_hist, 1, &histSize, &histRange, uniform, accumulate);
	calcHist(&bgr_planes[2], 1, 0, Mat(), r_hist, 1, &histSize, &histRange, uniform, accumulate);
	int hist_w = 512, hist_h = 400;
	int bin_w = cvRound((double)hist_w / histSize);
	Mat histImage(hist_h, hist_w, CV_8UC3, Scalar(0, 0, 0));
	normalize(b_hist, b_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat());
	normalize(g_hist, g_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat());
	normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat());
	for (int i = 1; i < histSize; i++)
	{
		line(histImage, Point(bin_w*(i - 1), hist_h - cvRound(b_hist.at<float>(i - 1))),
			Point(bin_w*(i), hist_h - cvRound(b_hist.at<float>(i))),
			Scalar(255, 0, 0), 2, 8, 0);
		line(histImage, Point(bin_w*(i - 1), hist_h - cvRound(g_hist.at<float>(i - 1))),
			Point(bin_w*(i), hist_h - cvRound(g_hist.at<float>(i))),
			Scalar(0, 255, 0), 2, 8, 0);
		line(histImage, Point(bin_w*(i - 1), hist_h - cvRound(r_hist.at<float>(i - 1))),
			Point(bin_w*(i), hist_h - cvRound(r_hist.at<float>(i))),
			Scalar(0, 0, 255), 2, 8, 0);
	}
	imshow("Source image", src);
	imshow("calcHist Demo", histImage);
	waitKey();
	return EXIT_SUCCESS;
}
// ========================

// example : histogram equalization
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;
int main(int argc, char** argv)
{
	Mat src = imread("histogram.png", IMREAD_GRAYSCALE);
	if (src.empty())
	{
		return EXIT_FAILURE;
	}
	Mat dst;
	equalizeHist(src, dst);
	imshow("Source image", src);
	imshow("Equalized image", dst);
	waitKey();
	return EXIT_SUCCESS;
}

การปรับค่าความสว่าง ด้วย Log Transformation การปรับค่า เช่นตัดหมอก

การปรับค่าให้เท่ากัน

 example : logarithmic transformation
#include <opencv2/opencv.hpp>
using namespace cv;
int main() {
	//Mat input_image = imread("lena.png", IMREAD_GRAYSCALE);
	Mat input_image = imread("histogram.png", IMREAD_GRAYSCALE);
	Mat processed_image;

	input_image.convertTo(processed_image, CV_32F);
	processed_image = processed_image + 1;
	log(processed_image, processed_image);
	normalize(processed_image, processed_image, 0, 255, NORM_MINMAX);
	convertScaleAbs(processed_image, processed_image);
	//applyColorMap(processed_image, processed_image, COLORMAP_RAINBOW); //COLORMAP_JET);

	imshow("Input image", input_image);
	imshow("Processed Image", processed_image);
	waitKey(0);

	return 0;
}