c++ - OpenCV 检测变暗的矩形

Question

我正在尝试使用 OpenCV 来隔离覆盖有大量文本的半透明变暗矩形区域。这些矩形区域在窗口中的大小和位置可以变化。有没有办法检测这些变暗的区域？

也许在显示暗区叠加之前应用一些差异操作并与帧进行比较会更容易？

Answer 1

这应该会为您提供基于两张图像的所有边界框。

#include <cv.h>
#include <highgui.h>

using namespace cv;

Mat im = imread("original.jpg");
Mat im2 = imread("darkened.jpg");

Mat diff_im = im - im2;

Mat diff_im_binary;
threshold(diff_im, diff_im_binary, 30, 255, THRESH_BINARY);

findContours(diff_im_binary, contours, hierarchy, CV_RETR_TREE,  CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );

 /// Approximate contours to polygons + get bounding rects and circles
 vector<vector<Point> > contours_poly( contours.size() );
 vector<Rect> boundRect( contours.size() );
 vector<Point2f>center( contours.size() );
 vector<float>radius( contours.size() );

 for( int i = 0; i < contours.size(); i++ )
 { 
     approxPolyDP( Mat(contours[i]), contours_poly[i], 3, true );
     boundRect[i] = boundingRect( Mat(contours_poly[i]) );
 }