android opencv 裁切多边形 opencv截取圆形区域

转载

jacksky 2023-11-02 13:38:48

OpenCV视频中分割圆形区域，利用判断图中的点是否在画的圆内，如果在圆内，则不变色；如果不在圆内，则改变它的的颜色。从而只能看到圆内的视频，并且可以把圆形部分截取，利用的是ROI（感兴趣区域），但是因为图片必须是矩形的，所以ROI也只能是矩形，截取的圆外接矩形。

使用的开发工具

OPENCV版本：OpenCV2.4.13

操作系统：windows10

VS版本：VS2015专业版

加载视频

加载视频有两种方法：一种是采用摄像头，另外一种是从视频文件中读入。但是需要注意的是从摄像头加载视频，最好先设定摄像头的显示窗口大小，width和height。视频文件就不需要了，因为视频文件有固定的宽和高，把每帧图片赋给新创建的图片之后，可以直接使用cols和rows属性，摄像头的话就需要使用到设定的width和height。

1、摄像头设置窗口大小

capture.set(CV_CAP_PROP_FRAME_WIDTH, 640);
capture.set(CV_CAP_PROP_FRAME_HEIGHT, 480);

2、AVI视频文件注意路径不要弄错，或者直接和.cpp源文件放在一块，是双斜杠\\

鼠标操作

这个链接有鼠标操作的一些解释，有需要的话，可以看看

画圆和框

这里画圆是先根据画线来确定的，画的线的长度就是圆的半径，半径利用勾股定理求得，圆心就是线段的最后一个点。

1、画圆函数

//【画圆】
void Draw_circle(Point pt_center, int pt_radius)
{
	circle(srcImage, pt_center, pt_radius, Scalar(0, 255, 0), 1, 8, 0);
}

2、画框函数

//【画框】
void Draw_rectangle(Point pt1, Point pt2)
{
	rectangle(srcImage, pt1, pt2, Scalar(0, 255, 0), 2, 8, 0);
}

3、勾股定理求半径

把圆形周围的颜色改变

画完圆之后，需要把圆周围颜色改变，而圆内不变。遍历图片，然后进行变色。

1、蓝色通道B

srcImage.at<Vec3b>(Point(x, y))[0] = 255;

2、绿色通道G

srcImage.at<Vec3b>(Point(x, y))[1] = 0;

3、红色通道R

srcImage.at<Vec3b>(Point(x, y))[2] = 0;

4、循环遍历，然后改变颜色

for (int x = 0; x < srcImage.cols; x++)
			{
				for (int y = 0; y < srcImage.rows; y++)
				{
					int temp = ((x - center.x) * (x - center.x) + (y - center.y) *(y - center.y));
					if (temp < (radius * radius))
					{
						//srcImage.at<Vec3b>(Point(x, y))[0] = 0;
						//srcImage.at<Vec3b>(Point(x, y))[1] = 255;
						//srcImage.at<Vec3b>(Point(x, y))[2] = 0;
					}
					else
					{
						srcImage.at<Vec3b>(Point(x, y))[0] = 255;
						srcImage.at<Vec3b>(Point(x, y))[1] = 0;
						srcImage.at<Vec3b>(Point(x, y))[2] = 0;
					}
				}
			}

截取圆形区域

1、把圆的外接矩形当做ROI

Mat imageROI = srcImage(Rect(center.x - radius, center.y - radius, radius * 2, radius * 2));

2、截取并保存

imshow("【logo】", logoImage);
imwrite("logo.jpeg", logoImage);

效果图

android opencv 裁切多边形 opencv截取圆形区域_Image

源代码

#include<opencv2/opencv.hpp>
#include<iostream>
#include <math.h>

using namespace std;
using namespace cv;

void Draw_rectangle(Point pt1, Point pt2);
void on_mouse(int event, int x, int y, int flags, void* ustc);
void Draw_circle(Point pt_center, int pt_radius);
void Draw_line(Point pt1, Point pt2, Scalar color);

Mat srcImage;
Point pre_pt = (0, 0), pre_pt_first, pre_pt_first1;//鼠标点
Point cur_pt = (0, 0), cur_pt_end, cur_pt_end1, center, pt_center;
float radius, A, B;
bool flag1 = false;
bool flag2 = false;
bool flag3 = false;

#define WINDOW_NAME "【drawing】"

int main()
{
	VideoCapture capture("C:\\Users\\Administrator\\Desktop\\1.avi");
	capture.set(CV_CAP_PROP_FRAME_WIDTH, 640);
	capture.set(CV_CAP_PROP_FRAME_HEIGHT, 480);

	while (true)
	{
		capture >> srcImage;
		/*if (!capture.isOpened())//判断摄像头是否打开  
		{
			cout << "视频加载失败 ！" << endl;
		}*/
		if(srcImage.empty())
		{
			cout << "视频加载失败 ！" << endl;
			return -1;
		}
		setMouseCallback("【采集视频】", on_mouse, 0);
		if (flag3 == true)
		{
			Draw_circle(center, radius);
			for (int x = 0; x < srcImage.cols; x++)
			{
				for (int y = 0; y < srcImage.rows; y++)
				{
					int temp = ((x - center.x) * (x - center.x) + (y - center.y) *(y - center.y));
					if (temp < (radius * radius))
					{
						//srcImage.at<Vec3b>(Point(x, y))[0] = 0;
						//srcImage.at<Vec3b>(Point(x, y))[1] = 255;
						//srcImage.at<Vec3b>(Point(x, y))[2] = 0;
					}
					else
					{
						srcImage.at<Vec3b>(Point(x, y))[0] = 255;
						srcImage.at<Vec3b>(Point(x, y))[1] = 0;
						srcImage.at<Vec3b>(Point(x, y))[2] = 0;
					}
				}
			}
			Mat imageROI = srcImage(Rect(center.x - radius, center.y - radius, radius * 2, radius * 2));
			Mat logoImage = imageROI;
			imshow("【logo】", logoImage);
			imwrite("logo.jpeg", logoImage);
		}
		imshow("【采集视频】", srcImage);
		waitKey(1);
	}
	return 0;
}

//【画线】
void Draw_line(Point pt1, Point pt2, Scalar color)
{
	line(srcImage, pt1, pt2, color, 2, CV_AA);
}

//【画框】
void Draw_rectangle(Point pt1, Point pt2)
{
	rectangle(srcImage, pt1, pt2, Scalar(0, 255, 0), 2, 8, 0);
}
//【画圆】
void Draw_circle(Point pt_center, int pt_radius)
{
	circle(srcImage, pt_center, pt_radius, Scalar(0, 255, 0), 1, 8, 0);
}

//鼠标操作
void on_mouse(int event, int x, int y, int flags, void* ustc)
{
	char temp_1[20];
	if (event == CV_EVENT_LBUTTONDOWN)//左键按下
	{
		flag1 = true;
		pre_pt = Point(x, y);
		pre_pt_first = pre_pt;
		//sprintf(temp_1,"x:%d,y:%d",x,y);    
		//putText(src,temp_1,Point(x,y),FONT_HERSHEY_SIMPLEX,0.5,Scalar(255,255,255));  
		imshow("【采集视频】", srcImage);
	}
	else if (event == EVENT_MOUSEMOVE && (flags & EVENT_FLAG_LBUTTON))//左键按下并且鼠标移动
	{
		if (flag1 == true)
		{
			flag2 = true;
		}

		cur_pt = Point(x, y);
		sprintf(temp_1, "x:%d,y:%d", x, y);
		putText(srcImage, temp_1, Point(x, y), FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 255, 255));
		A = cur_pt.x - pre_pt_first.x;
		B = cur_pt.y - pre_pt_first.y;
		radius = sqrt(A*A + B*B);
		center = Point(cur_pt.x, cur_pt.y);
		Draw_line(Point(pre_pt_first.x, pre_pt_first.y), Point(cur_pt.x, cur_pt.y), Scalar(0, 0, 255));
		Draw_circle(center, radius);
		imshow("【采集视频】", srcImage);
	}
	else if (event == CV_EVENT_LBUTTONUP)//左键弹起
	{
		if (flag2 == true)
		{
			flag3 = true;
		}

		cur_pt = Point(x, y);
		cur_pt_end = cur_pt;
		//sprintf(temp_1, "x:%d,y:%d", x, y);
		//putText(srcImage1, temp_1, Point(x, y), FONT_HERSHEY_SIMPLEX, 0.4, Scalar(0, 255, 255));
		//circle(srcImage1, cur_pt, 3, cvScalar(255, 0, 0), CV_FILLED, CV_AA, 0);
		A = cur_pt_end.x - pre_pt_first.x;
		B = cur_pt_end.y - pre_pt_first.y;
		radius = sqrt(A*A + B*B);
		center = Point(cur_pt_end.x, cur_pt_end.y);
		Draw_line(Point(pre_pt_first.x, pre_pt_first.y), Point(cur_pt.x, cur_pt.y), Scalar(0, 0, 255));
		Draw_circle(center, radius);
		imshow("【采集视频】", srcImage);
	}
}

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