1.创建一个100*100的两维三通道矩阵,初始值为全0
a.使用cv::circle在矩阵中画一个圆;
b.显示这个图片。
Mat src3 = Mat(100,100,CV_8UC3, Scalar::all(0));
Point pt(50, 50);
circle(src3, pt, 40, Scalar(0, 255, 0));
imshow("1", src3);
waitKey(0);
2.创建一个100*100的两维三通道矩阵,初始值为全0
a.使用at<>这种遍历方式,画一个由(20,5)到(40,20)的绿色矩形
b.显示这个图片。
y在20-40之间,x在5-20之间。
Mat m1 = Mat(100, 100, CV_8UC3, Scalar(0));
for (int i = 0; i < m1.rows; i++)
{
for (int j = 0; j < m1.cols; j++)
{
if (j >= 20 && j <= 40 && i >= 5 && i <= 20)
{
m1.at(j, i)[0] = 0;
m1.at(j, i)[1] = 255;
m1.at(j, i)[2] = 0;
}
}
}
imshow("execrise 2", m1);
waitKey();
return 0;
3、第二题同样的效果,但是使用指针方式;
Mat m1 = Mat(100, 100, CV_8UC3, Scalar(0));
for (int i = 0; i < m1.rows; i++)
{
uchar *outData = m1.ptr(i);
for (int j = 0; j < m1.cols; j++)
{
if (j >= 20 && j <= 40 && i >= 5 && i <= 20)
{
outData[j*3+1] = 255;
}
}
}
imshow("execrise 3", m1);
waitKey();
return 0;
4、练习使用ROI。创建一个210*210的单通道图像。使用ROI和setto方法,由边缘到中间,使得图像的值分别为0,20,40,……200。每一层都为10像素宽;
setTo函数
Mat& setTo(InputArray value, InputArray mask=noArray());
把矩阵mask中元素不为0的点全部变为value值,是0保持不变;
Mat m1 = Mat(210, 210, CV_8U, Scalar(0));
for (int i = 0; i < 105; i=i+10)
{
Mat roi = m1(Rect(i, i, 210 - i * 2, 210 - i * 2));
roi.setTo(i * 2);
}
imshow("execrise 4", m1);
waitKey();
return 0;
5、练习使用ROI。创建一个100*100的单通道图像,分别为(5,10)和(50,60)选择一块(20*30)的区域,并进行bitwise_not运算,观察结果;
Mat m1 = Mat(100, 100, CV_8U, Scalar(0));
Mat roi1 = m1(Rect(5, 10, 20, 30));
Mat roi2 = m1(Rect(50, 60, 20, 30));
bitwise_not(roi1, roi1);
bitwise_not(roi2, roi2);
imshow("execrise 5", m1);
waitKey();
return 0;
6、练习使用cv::compare()。读入lena.jpg,使用cv::split()将其区分为3个通道
a.显示绿色通道
b.将绿通道克隆两次 clone1 clone2
c.寻找到绿通道最大最小值
d.设置clone1的值为 thresh = (unsigned char)((maximum - minimum)/2.0)
e.设置clone2为0,并使用 cv::compare (green_image, clone1, clone2,cv::CMP_GE)。这个时候clone2获得的是什么结果?
f. cv::subtract(green_image,thresh/2,green_image,clone2),显示最终结果
Mat clone1, clone2;
vectorbgr_planes;
Mat src = imread("lena.jpg", 1);
split(src, bgr_planes);
Mat green = bgr_planes[1];
imshow("green", green);
clone1 = green.clone();
clone2 = green.clone();
double minPixelValue, maxPixelValue;
int minPixelID, maxPixelID;
minMaxIdx(green, &minPixelValue, &maxPixelValue, &minPixelID, &maxPixelID);
double thresh = (unsigned char)((maxPixelValue - minPixelValue) / 2.0);
int ithresh = (int)thresh;
clone1 = Mat(clone1.size(), clone1.type(), Scalar(ithresh));
clone2 = Mat(clone2.size(), clone2.type(), Scalar(0));
compare(green, clone1, clone2, CMP_GE);
subtract(green, thresh / 2, green, clone2);
imshow("execrise 6", clone2);
waitKey();
return 0;
Mat src = imread("lena.jpg", 1);
src
clone1 = green.clone();
clone1
clone1 = Mat(clone1.size(), clone1.type(), Scalar(ithresh));
clone1
clone2 = Mat(clone2.size(), clone2.type(), Scalar(0));
clone2
compare(green, clone1, clone2, CMP_GE);
clone2
subtract(green, thresh / 2, green, clone2);
green,
题目1:a.读取lena.jpg;
b.分别以(250,250)(350,350)为中心,绘制两个半径为150的红色圆;
c.由(250,250)到(350,350)绘制一条红色直线
d.任意位置,puttext 大写“LOVE”红色
Mat src = imread("lena.jpg", 1);
circle(src, Point(250, 250), 150, Scalar(0, 0, 255), 5);
circle(src, Point(350, 250), 150, Scalar(0, 0, 255), 5);
line(src, Point(250, 250), Point(350, 250), Scalar(0, 0, 255), 5);
putText(src, "LOVE", Point(50, 30), CV_FONT_HERSHEY_DUPLEX, 1.0f, Scalar(0, 0, 255));
imshow("execrise 5", src);
waitKey();
return 0;