[英]How to count the number of pixels in each circle in OpenCV?
我目前有以下來源圖片: 源圖片
我的目標是找到每個矩形內紅色像素的數量。 但是,我不知道如何進行。 我已經使用區域(30 * 30)和countNonZero通過分別手動裁剪並另存為單獨的圖像來查找每個圓圈的像素數。 但是,我想在整個圖像中實現它,我可以在邊界矩形中進行迭代。
編輯:如果有幫助,這是我用來獲取邊界矩形的代碼。
for (int i = 0; i < contours.size(); i++)
{
approxPolyDP(Mat(contours[i]), contours_poly[i], 0.1, true);
//Get the width and heights of the bounding rectangles
int w = boundingRect(Mat(contours[i])).width;
int h = boundingRect(Mat(contours[i])).height;
//Apply aspect ratio for filtering rects (optional)
double ar = (double)w / h;
//Apply a bounding Rects/Circles
//Rect/contour filter optional
if (hierarchy[i][3] == -1) //No parent
if ((w >= 28 && w <= 32) && (h >= 28 && h <= 32) && ar < 1.1 && ar > 0.9) {
//Apply a bounding Rects/Circles
boundRect[i] = boundingRect(Mat(contours_poly[i]));
minEnclosingCircle((Mat)contours_poly[i], center[i], radius[i]);
//Add to a new
filtered_contours.push_back(contours_poly[i]);
std::cout << i << " w: " << w << " h: " << h << std::endl;
}
}
也許這對您有幫助。
// Load image.
cv::Mat circles = cv::imread("circles.jpg", cv::IMREAD_GRAYSCALE);
// Use simple threshold to get rid of compression artifacts.
cv::Mat circlesThr;
cv::threshold(circles, circlesThr, 128, 255, cv::THRESH_BINARY_INV);
// Find contours in binary image (cv::RETR_EXTERNAL -> only most outer contours).
std::vector<std::vector<cv::Point>> contours;
std::vector<cv::Vec4i> hierarchy;
cv::findContours(circlesThr, contours, hierarchy, cv::RETR_EXTERNAL, cv::CHAIN_APPROX_NONE);
// Iterate all contours...
// Iterate all contours...
for (std::vector<cv::Point>& contour : contours)
{
// Determine bounding rectangle of contour.
cv::Rect rect = cv::boundingRect(contour);
// Count non-zero pixels within bounding rect.
std::string count = std::to_string(cv::countNonZero(circlesThr(rect)));
// Output text to image.
cv::putText(circlesThr, count, cv::Point(rect.x - 5, rect.y - 5), cv::FONT_HERSHEY_SIMPLEX, 0.5, cv::Scalar(255));
}
// Save output image.
cv::imwrite("output.jpg", circlesThr);
結果是:
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