OpenCV(5): 图像基本操作(读取/保存图像，修改图像的像素值)

谁践踏了优雅 2023-02-20 06:44 43阅读 0赞

### 文章目录 ###

*  1 读取图像
 *  2 保存图像
 *  3 修改灰度图像的像素值
 *  4 修改彩色图像的像素值
 *  参考资料

**注：转载请标明原文出处链接：**https://xiongyiming.blog.csdn.net/article/details/106937362

# 1 读取图像 #

**运行结果**

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3phaXNodWl5aWZhbmd4eW0_size_16_color_FFFFFF_t_70_pic_center]

# 2 保存图像 #

**运行结果**

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3phaXNodWl5aWZhbmd4eW0_size_16_color_FFFFFF_t_70_pic_center 1]

# 3 修改灰度图像的像素值 #

**运行结果**

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3phaXNodWl5aWZhbmd4eW0_size_16_color_FFFFFF_t_70_pic_center 2]

# 4 修改彩色图像的像素值 #

#include <opencv2/core/core.hpp> 
    #include <opencv2/imgcodecs.hpp> 
    #include <opencv2/opencv.hpp>
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/highgui/highgui_c.h>
    
    #include <iostream>
    #include <math.h>
    
    
    
    
    using namespace cv;
    using namespace std;
    int main(int argc, char** args) {
        
    	Mat src = imread("ZXP1.jpg", IMREAD_UNCHANGED);
    	if (src.empty()) {
        
    		cout << "could not find the image resource..." << std::endl;
    		return -1;
    	}
    	namedWindow("Original Image", CV_WINDOW_AUTOSIZE);
    	imshow("Original Image", src);
    
    	Mat gray_src;
    	cvtColor(src, gray_src, CV_BGR2GRAY);
    	namedWindow("Output Image_1", CV_WINDOW_AUTOSIZE);
    	imshow("Output Image_1", gray_src);
    
    	int height = gray_src.rows;
    	int width = gray_src.cols;
    	for (int row = 0; row < height; row++)
    	{
        
    		for (int col = 0; col < width; col++)
    		{
        
    			int gray_value = gray_src.at<uchar>(row, col);
    			gray_src.at<uchar>(row, col) = 255 - gray_value;//修改像素值
    		}
    	}
    
    	namedWindow("Output Image_2", CV_WINDOW_AUTOSIZE);
    	imshow("Output Image_2", gray_src);
    
    	
    	int n = src.channels();
    	Mat dst;
    	dst.create(src.size(), src.type());//或者用dst = Mat(src.size(), src.type());
    
    	
    	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];
    
    				dst.at<Vec3b>(row, col)[0] = 255 - b ;
    				dst.at<Vec3b>(row, col)[1] = 255 - g ;
    				dst.at<Vec3b>(row, col)[2] = 255 - r ;
    		
    		}
    	}
    	
    
    	namedWindow("Output Image_3", CV_WINDOW_AUTOSIZE);
    	imshow("Output Image_3", dst);
    	
    	cout << src.type() << endl;
    	cout << gray_src.type() << endl;
    	cout << dst.type() << endl;
    
    
    
    	waitKey(0);
    
    	return 0;
    }

**运行结果**

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3phaXNodWl5aWZhbmd4eW0_size_16_color_FFFFFF_t_70_pic_center 3]

**Vec3b 与 Vec3f 比较**

1.  `Vec3b` 对应三通道的顺序是Blue、Green、Red 的uchar类型数据；
2.  `Vec3f` 对应三通道的float类型数据；
3.  `CV_8UC1` 转换到 `CV32F1` 实现方法为：`src.convertTo(dst, CV_32F);`

--------------------

# 参考资料 #

\[1\] [https://edu.51cto.com/course/7521.html?source=so][https_edu.51cto.com_course_7521.html_source_so]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3phaXNodWl5aWZhbmd4eW0_size_16_color_FFFFFF_t_70_pic_center 2]: https://img-blog.csdnimg.cn/20200624094013541.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3phaXNodWl5aWZhbmd4eW0=,size_16,color_FFFFFF,t_70#pic_center
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3phaXNodWl5aWZhbmd4eW0_size_16_color_FFFFFF_t_70_pic_center 3]: https://img-blog.csdnimg.cn/20200624094238635.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3phaXNodWl5aWZhbmd4eW0=,size_16,color_FFFFFF,t_70#pic_center
[https_edu.51cto.com_course_7521.html_source_so]: https://edu.51cto.com/course/7521.html?source=so