图像像素操作

• 灰度图像：img.at<uchar>(y,x)=128;
• RGB图像：img.at<Vec3b>(y,x)[0]=128;

lVec3b对应三通道的顺序是blue、green、red的uchar类型数据。

lVec3f对应三通道的float类型数据

#include<opencv2/opencv.hpp>
#include<iostream>
using namespace std;
using namespace cv;

int main() {
	Mat src,src_gray;
	src = imread("C:/Users/Luyubo/Pictures/Lena.jpg");
	cvtColor(src, src_gray, COLOR_RGB2GRAY);
	namedWindow("image", CV_WINDOW_AUTOSIZE);
	imshow("image", src);
	//不调用API的反差图，从像素级别进行反差。
	/*int height = src.rows;
	int width = src.cols;
	for (int row = 0; row < height; row++) {
		for (int col = 0; col < width; col++) {
			int b = src.at<Vec3b>(row, col)[0];
			int g = src.at<Vec3b>(row, col)[1];
			int r = src.at<Vec3b>(row, col)[2];
			src.at<Vec3b>(row, col)[0] = 255 - b;
			src.at<Vec3b>(row, col)[1] = 255 - g;
			src.at<Vec3b>(row, col)[2] = 255 - r;
		}
	}*/
	//调用API进行反差。
	bitwise_not(src, src);
	imshow("contrastimage", src);
	waitKey(0);
	destroyAllWindows();
	return 0;
}