opencv修改图像的像素值

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本节知识点

1,读写图像

a,imread可以加载灰度图或者RGB图像

b,imwrite保存图像，类型由扩展名决定

2,读写图像的像素

a,读取灰度图像像素点的值(CV_8UC1)

Scalar intensity=img.at<uchar>(y,x);

或者

Scalar intensity=img.at<uchar>(Point(x,y))

3,读一个RGB像素点的像素值

Vec3f intensity=img.at<Vec3f>(y,x)

float blue=intensity.val[0]

float green=intensity.val[1]

float red=intensity.val[2]

4,修改像素值

a,修改灰度图像像素值

img.at<uchar>(y,x)=128

b,修改RGB三通道图像像素值

img.at<Vec3b>(y,x)[0]=128;//blue 通道

img.at<Vec3b>(y,x)[1]=128;//green 通道

img.at<Vec3b>(y,x)[2]=128;//red 通道

5,生成一副空白图像

img=Scalar(0)

6,ROI(感兴趣区域选择)

Rect r(10,10,200,200)

Mat src=img(r);

7,Vec3b:对应的三通道的顺序是blue,green,red的uchar类型数据

下面给出修改图像三通道像素值的各种效果，大部分是反色处理

代码实现

#include <opencv2\core\core.hpp>#include <opencv2\imgcodecs.hpp>#include <opencv2\opencv.hpp>#include <opencv2\highgui\highgui.hpp>#include <iostream>using namespace cv;using namespace std;int main(int argc, char** args){Mat image = imread("test.jpg");if (image.empty()){cout << "不能加载图像..." << std::endl;return -1;}Mat dst;cvtColor(image, dst, CV_BGR2GRAY);int height = image.rows;int width = image.cols;int channels = image.channels();printf("height=%d,width=%d channels=%d",height,width,channels);for (int row = 0; row < height;row++){for (int col = 0; col < width;col++){if (channels==3){//image.at<Vec3b>(row, col)[0] = 0;//blue 通道//image.at<Vec3b>(row, col)[1] = 0;//green 通道//image.at<Vec3b>(row, col)[2] = 255 - image.at<Vec3b>(row, col)[2];// red 通道//image.at<Vec3b>(row, col)[0] = 255 - image.at<Vec3b>(row, col)[0];//blue 通道//image.at<Vec3b>(row, col)[1] = 255 - image.at<Vec3b>(row, col)[1];//green 通道//image.at<Vec3b>(row, col)[2] = 255 - image.at<Vec3b>(row, col)[2];// red 通道image.at<Vec3b>(row, col)[0] = 0;//blue 通道image.at<Vec3b>(row, col)[1] = 255 - image.at<Vec3b>(row, col)[1];//green 通道image.at<Vec3b>(row, col)[2] = 0;// red 通道//image.at<Vec3b>(row, col)[1] = 0;//green 通道//image.at<Vec3b>(row, col)[2] = 0;// red 通道}//else if (channels==1)//{//dst.at<uchar>(row, col) = 255 - dst.at<uchar>(row, col);//}}}namedWindow("输出图像-2", CV_WINDOW_AUTOSIZE);imshow("输出图像-2", image);waitKey(0);return 0;}

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