OpenCv截取任意形状 -- 实例

蔚落 2022-01-17 20:01 240阅读 0赞

OpenCV实例： 在图中按下鼠标画一个任意形状的区域，右击截取该区域内的图像，其中copyTo函数可根据掩码提取图片内容。

#include "pch.h"
    #include<iostream>
    #include<opencv2\opencv.hpp>
    using namespace std;
    using namespace cv;
    
    cv::Mat img;
    cv::Mat imgMask;
    cv::Mat imgOrg;
    Point lastPt;
    Point firstPt;
    
    /*
    double cv::threshold(	
    InputArray 	src,		// src input array (multiple-channel, 8-bit or 32-bit floating point).
    OutputArray 	dst,	// dst output array of the same size and type and the same number of channels as src.
    double 	thresh,			// thresh threshold value.
    double 	maxval,			// maxval maximum value to use with the THRESH_BINARY and THRESH_BINARY_INV thresholding types.
    int 	type			// type	thresholding type (see ThresholdTypes).
    )
    */
    
    void on_mouse_callback(int event, int x, int y, int flags, void* yybird)
    {
    	if (!img.data){
    		printf("image is empty!\n");
    		return;
    	}
    
    	Point pt = Point(x, y);
    	if (event == cv::EVENT_LBUTTONUP ) { //|| !(flags & cv::EVENT_FLAG_LBUTTON)		
    		line(img, pt, firstPt, Scalar(0, 0, 255), 1, 8, 0);
    		line(imgMask, pt, firstPt, Scalar(255, 255, 255), 1, 8, 0);
    		imshow("image", img);		
    	}
    	else if (event == cv::EVENT_LBUTTONDOWN) {
    		firstPt = lastPt = Point(x, y);
    	}
    	else if( (event == cv::EVENT_MOUSEMOVE) && (flags & cv::EVENT_FLAG_LBUTTON) )
    	{
    		if (lastPt.x < 0) { lastPt = pt; }
    		line(img, lastPt, pt, Scalar(0, 0, 255), 1, 8, 0); // display a red  line  
    		line(imgMask, lastPt, pt, Scalar(255, 255, 255), 1, 8, 0);
    		imshow("image", img);
    
    		lastPt = pt;
    	}
    	
    	if (event == cv::EVENT_RBUTTONUP)//右击选择框图
    	{
    		//fill color
    		floodFill(imgMask, Point(x, y), Scalar(255, 255, 255));
    
    		// make a mask
    		Mat grayMask = imgMask.clone();
    		// the Scalar(255,255,255) will be converted to Scalar(255) gray data
    		cvtColor(imgMask, grayMask, COLOR_BGR2GRAY);  
    		// change the value to see what will happen...
    		cv::threshold(grayMask, grayMask, 254, 255, THRESH_BINARY);  
    		imshow("grayMask", grayMask);
    
    		// extract region
    		imgOrg.copyTo(imgMask, grayMask);
    		imshow("Image in Mask", imgMask);
    	}
    }
    
    int main(int argc, char** argv)
    {
    	string strPath = "C:/Users/Administrator/img_7233.jpg";
    	imgOrg = cv::imread(strPath.c_str(), 1);
    
    	img = imgOrg.clone();
    	imgMask = imgOrg.clone();     // 255 for easy detection
    	imgMask = Scalar::all(0);
    
    	namedWindow("image", 1);
    	imshow("image", img);
    	cv::setMouseCallback("image", on_mouse_callback, 0);
    	waitKey(0);
    	return 0;
    }