C++HOG算法实现检测摄像头四角阴影占比
时间: 2023-06-17 08:05:15 浏览: 58
HOG算法是一种用于目标检测的特征提取方法,可用于检测图像中的物体。下面是一种使用OpenCV库和C++编程语言实现HOG算法检测摄像头四角阴影占比的方法:
1. 首先,需要打开摄像头并捕获实时视频帧。可以使用OpenCV中的VideoCapture类来实现:
```
cv::VideoCapture cap(0); // 0代表摄像头编号
if (!cap.isOpened()) {
std::cerr << "Cannot open camera." << std::endl;
return -1;
}
```
2. 接下来,需要创建一个HOG描述符并设置参数。可以使用OpenCV中的HOGDescriptor类来实现。这里我们需要设置窗口大小、块大小、块步长、细胞大小等参数:
```
cv::HOGDescriptor hog;
hog.winSize = cv::Size(64, 64); // 窗口大小
hog.blockSize = cv::Size(16, 16); // 块大小
hog.blockStride = cv::Size(8, 8); // 块步长
hog.cellSize = cv::Size(8, 8); // 细胞大小
```
3. 然后,我们需要定义一个检测函数,用于检测图像中的目标。这里我们将检测四个角落的阴影占比。首先,我们需要将每个角落的位置定义为一个矩形区域,然后计算每个区域内的像素点占比。具体实现如下:
```
double detectShadowRatio(cv::Mat frame) {
cv::Rect topLeft(0, 0, frame.cols / 4, frame.rows / 4);
cv::Rect topRight(frame.cols * 3 / 4, 0, frame.cols / 4, frame.rows / 4);
cv::Rect bottomLeft(0, frame.rows * 3 / 4, frame.cols / 4, frame.rows / 4);
cv::Rect bottomRight(frame.cols * 3 / 4, frame.rows * 3 / 4, frame.cols / 4, frame.rows / 4);
int shadowPixels = 0;
int totalPixels = 0;
// 计算每个区域内的像素点占比
shadowPixels += cv::countNonZero(frame(topLeft) < 100);
totalPixels += topLeft.width * topLeft.height;
shadowPixels += cv::countNonZero(frame(topRight) < 100);
totalPixels += topRight.width * topRight.height;
shadowPixels += cv::countNonZero(frame(bottomLeft) < 100);
totalPixels += bottomLeft.width * bottomLeft.height;
shadowPixels += cv::countNonZero(frame(bottomRight) < 100);
totalPixels += bottomRight.width * bottomRight.height;
// 计算阴影占比
return double(shadowPixels) / totalPixels;
}
```
4. 最后,在主函数中,我们需要不断捕获视频帧,并调用检测函数来检测阴影占比。具体实现如下:
```
cv::Mat frame;
while (true) {
cap >> frame;
if (frame.empty()) {
break;
}
cv::cvtColor(frame, frame, cv::COLOR_BGR2GRAY);
double ratio = detectShadowRatio(frame);
std::cout << "Shadow ratio: " << ratio << std::endl;
cv::imshow("Frame", frame);
if (cv::waitKey(1) == 'q') {
break;
}
}
```
完整代码如下:
```
#include <iostream>
#include <opencv2/opencv.hpp>
double detectShadowRatio(cv::Mat frame) {
cv::Rect topLeft(0, 0, frame.cols / 4, frame.rows / 4);
cv::Rect topRight(frame.cols * 3 / 4, 0, frame.cols / 4, frame.rows / 4);
cv::Rect bottomLeft(0, frame.rows * 3 / 4, frame.cols / 4, frame.rows / 4);
cv::Rect bottomRight(frame.cols * 3 / 4, frame.rows * 3 / 4, frame.cols / 4, frame.rows / 4);
int shadowPixels = 0;
int totalPixels = 0;
shadowPixels += cv::countNonZero(frame(topLeft) < 100);
totalPixels += topLeft.width * topLeft.height;
shadowPixels += cv::countNonZero(frame(topRight) < 100);
totalPixels += topRight.width * topRight.height;
shadowPixels += cv::countNonZero(frame(bottomLeft) < 100);
totalPixels += bottomLeft.width * bottomLeft.height;
shadowPixels += cv::countNonZero(frame(bottomRight) < 100);
totalPixels += bottomRight.width * bottomRight.height;
return double(shadowPixels) / totalPixels;
}
int main() {
cv::VideoCapture cap(0);
if (!cap.isOpened()) {
std::cerr << "Cannot open camera." << std::endl;
return -1;
}
cv::HOGDescriptor hog;
hog.winSize = cv::Size(64, 64);
hog.blockSize = cv::Size(16, 16);
hog.blockStride = cv::Size(8, 8);
hog.cellSize = cv::Size(8, 8);
cv::Mat frame;
while (true) {
cap >> frame;
if (frame.empty()) {
break;
}
cv::cvtColor(frame, frame, cv::COLOR_BGR2GRAY);
double ratio = detectShadowRatio(frame);
std::cout << "Shadow ratio: " << ratio << std::endl;
cv::imshow("Frame", frame);
if (cv::waitKey(1) == 'q') {
break;
}
}
return 0;
}
```