在新版本的opencv中，我们失去了一些函数例如sift，以及这次我们需要使用的grabCut，因此我们需要安装OpenCV-contrib。 新手（我）安装可以参考这篇csdn：VS2017和opencv-4.1.2配置。 （注意一定要选择相同版本的opencv与opencv-contrib）
我遇到的问题：无法打开opencv_stitching412d.lib 在实际使用时，例如错误信息为：无法打开opencv_stitching412d.lib。 解决方法： 1、首先打开你在cmake过程中选择的空文件夹（cmake操作中） 到路径：D:\opencv_contrib-4.1.2\build\lib\Debug，（这是我的文件路径） 去检查文件夹中是否有你所缺失的lib文件（下图红线所示） 我在报错的时候是没有这个包的，在求助老师后，方才得知VS在编译时也是需要联网下载的。就如git clone和python的pip一样，有些资源是很难下载的。 2、打开OpenCV.sln，在解决方案资源管理器中，找到modules中的opencv_stitching，右键–生成。等待编译结束。这个时候，我遇到的错误是：我的xfeatures2d.lib缺失了（我现在配好了所以没法截图），而这个xfeatures2d.lib是opencv_stitching的依赖项（由我之前配sift的经验来看，这个xfeatures2d.lib**应该是很多东西的依赖项）。 最终在老师的帮助下，我得到了缺失的文件资源
将得到的压缩包解压到路径：图中那个build就是你cmake存放生成文件的文件夹 3、回到VS，在modules中找到opencv_xfeatures2d，右键–生成（我在添加了文件之后就生成成功了）。 然后这时再选中opencv_stitching，右键–生成，等待编译结束。这个时候注意，有可能还是会报错。你转到第一步中的那个文件夹，此时应该就存在了opencv_stitching412d.lib。至此，问题得到解决。
cv::grabCut的函数原型如下：
void cv::grabCut ( InputArray img, InputOutputArray mask, Rect rect, InputOutputArray bgdModel, InputOutputArray fgdModel, int iterCount, int mode = GC_EVAL )其中各个变量的解释： 今天时间有限，我们就先来看看tutorial中给出的grabCut函数的示例。
#include "opencv2/imgcodecs.hpp" #include "opencv2/highgui.hpp" #include "opencv2/imgproc.hpp" #include <iostream> using namespace std; using namespace cv; static void help() { cout << "\nThis program demonstrates GrabCut segmentation -- select an object in a region\n" "and then grabcut will attempt to segment it out.\n" "Call:\n" "./grabcut <image_name>\n" "\nSelect a rectangular area around the object you want to segment\n" << "\nHot keys: \n" "\tESC - quit the program\n" "\tr - restore the original image\n" "\tn - next iteration\n" "\n" "\tleft mouse button - set rectangle\n" "\n" "\tCTRL+left mouse button - set GC_BGD pixels\n" "\tSHIFT+left mouse button - set GC_FGD pixels\n" "\n" "\tCTRL+right mouse button - set GC_PR_BGD pixels\n" "\tSHIFT+right mouse button - set GC_PR_FGD pixels\n" << endl; } const Scalar RED = Scalar(0, 0, 255); const Scalar PINK = Scalar(230, 130, 255); const Scalar BLUE = Scalar(255, 0, 0); const Scalar LIGHTBLUE = Scalar(255, 255, 160); const Scalar GREEN = Scalar(0, 255, 0); const int BGD_KEY = EVENT_FLAG_CTRLKEY; const int FGD_KEY = EVENT_FLAG_SHIFTKEY; static void getBinMask(const Mat& comMask, Mat& binMask) { if (comMask.empty() || comMask.type() != CV_8UC1) CV_Error(Error::StsBadArg, "comMask is empty or has incorrect type (not CV_8UC1)"); if (binMask.empty() || binMask.rows != comMask.rows || binMask.cols != comMask.cols) binMask.create(comMask.size(), CV_8UC1); binMask = comMask & 1; } class GCApplication { public: enum { NOT_SET = 0, IN_PROCESS = 1, SET = 2 }; static const int radius = 2; static const int thickness = -1; void reset(); void setImageAndWinName(const Mat& _image, const string& _winName); void showImage() const; void mouseClick(int event, int x, int y, int flags, void* param); int nextIter(); int getIterCount() const { return iterCount; } private: void setRectInMask(); void setLblsInMask(int flags, Point p, bool isPr); const string* winName; const Mat* image; Mat mask; Mat bgdModel, fgdModel; uchar rectState, lblsState, prLblsState; bool isInitialized; Rect rect; vector<Point> fgdPxls, bgdPxls, prFgdPxls, prBgdPxls; int iterCount; }; void GCApplication::reset() { if (!mask.empty()) mask.setTo(Scalar::all(GC_BGD)); bgdPxls.clear(); fgdPxls.clear(); prBgdPxls.clear(); prFgdPxls.clear(); isInitialized = false; rectState = NOT_SET; lblsState = NOT_SET; prLblsState = NOT_SET; iterCount = 0; } void GCApplication::setImageAndWinName(const Mat& _image, const string& _winName) { if (_image.empty() || _winName.empty()) return; image = &_image; winName = &_winName; mask.create(image->size(), CV_8UC1); reset(); } void GCApplication::showImage() const { if (image->empty() || winName->empty()) return; Mat res; Mat binMask; if (!isInitialized) image->copyTo(res); else { getBinMask(mask, binMask); image->copyTo(res, binMask); } vector<Point>::const_iterator it; for (it = bgdPxls.begin(); it != bgdPxls.end(); ++it) circle(res, *it, radius, BLUE, thickness); for (it = fgdPxls.begin(); it != fgdPxls.end(); ++it) circle(res, *it, radius, RED, thickness); for (it = prBgdPxls.begin(); it != prBgdPxls.end(); ++it) circle(res, *it, radius, LIGHTBLUE, thickness); for (it = prFgdPxls.begin(); it != prFgdPxls.end(); ++it) circle(res, *it, radius, PINK, thickness); if (rectState == IN_PROCESS || rectState == SET) rectangle(res, Point(rect.x, rect.y), Point(rect.x + rect.width, rect.y + rect.height), GREEN, 2); imshow(*winName, res); } void GCApplication::setRectInMask() { CV_Assert(!mask.empty()); mask.setTo(GC_BGD); rect.x = max(0, rect.x); rect.y = max(0, rect.y); rect.width = min(rect.width, image->cols - rect.x); rect.height = min(rect.height, image->rows - rect.y); (mask(rect)).setTo(Scalar(GC_PR_FGD)); } void GCApplication::setLblsInMask(int flags, Point p, bool isPr) { vector<Point> *bpxls, *fpxls; uchar bvalue, fvalue; if (!isPr) { bpxls = &bgdPxls; fpxls = &fgdPxls; bvalue = GC_BGD; fvalue = GC_FGD; } else { bpxls = &prBgdPxls; fpxls = &prFgdPxls; bvalue = GC_PR_BGD; fvalue = GC_PR_FGD; } if (flags & BGD_KEY) { bpxls->push_back(p); circle(mask, p, radius, bvalue, thickness); } if (flags & FGD_KEY) { fpxls->push_back(p); circle(mask, p, radius, fvalue, thickness); } } void GCApplication::mouseClick(int event, int x, int y, int flags, void*) { // TODO add bad args check switch (event) { case EVENT_LBUTTONDOWN: // set rect or GC_BGD(GC_FGD) labels { bool isb = (flags & BGD_KEY) != 0, isf = (flags & FGD_KEY) != 0; if (rectState == NOT_SET && !isb && !isf) { rectState = IN_PROCESS; rect = Rect(x, y, 1, 1); } if ((isb || isf) && rectState == SET) lblsState = IN_PROCESS; } break; case EVENT_RBUTTONDOWN: // set GC_PR_BGD(GC_PR_FGD) labels { bool isb = (flags & BGD_KEY) != 0, isf = (flags & FGD_KEY) != 0; if ((isb || isf) && rectState == SET) prLblsState = IN_PROCESS; } break; case EVENT_LBUTTONUP: if (rectState == IN_PROCESS) { rect = Rect(Point(rect.x, rect.y), Point(x, y)); rectState = SET; setRectInMask(); CV_Assert(bgdPxls.empty() && fgdPxls.empty() && prBgdPxls.empty() && prFgdPxls.empty()); showImage(); } if (lblsState == IN_PROCESS) { setLblsInMask(flags, Point(x, y), false); lblsState = SET; showImage(); } break; case EVENT_RBUTTONUP: if (prLblsState == IN_PROCESS) { setLblsInMask(flags, Point(x, y), true); prLblsState = SET; showImage(); } break; case EVENT_MOUSEMOVE: if (rectState == IN_PROCESS) { rect = Rect(Point(rect.x, rect.y), Point(x, y)); CV_Assert(bgdPxls.empty() && fgdPxls.empty() && prBgdPxls.empty() && prFgdPxls.empty()); showImage(); } else if (lblsState == IN_PROCESS) { setLblsInMask(flags, Point(x, y), false); showImage(); } else if (prLblsState == IN_PROCESS) { setLblsInMask(flags, Point(x, y), true); showImage(); } break; } } int GCApplication::nextIter() { if (isInitialized) grabCut(*image, mask, rect, bgdModel, fgdModel, 1); else { if (rectState != SET) return iterCount; if (lblsState == SET || prLblsState == SET) grabCut(*image, mask, rect, bgdModel, fgdModel, 1, GC_INIT_WITH_MASK); else grabCut(*image, mask, rect, bgdModel, fgdModel, 1, GC_INIT_WITH_RECT); isInitialized = true; } iterCount++; bgdPxls.clear(); fgdPxls.clear(); prBgdPxls.clear(); prFgdPxls.clear(); return iterCount; } GCApplication gcapp; static void on_mouse(int event, int x, int y, int flags, void* param) { gcapp.mouseClick(event, x, y, flags, param); } int main(int argc, char** argv) { cv::CommandLineParser parser(argc, argv, "{@input| messi5.jpg |}"); help(); string filename = parser.get<string>("@input"); if (filename.empty()) { cout << "\nDurn, empty filename" << endl; return 1; } Mat image = imread(samples::findFile(filename), IMREAD_COLOR); if (image.empty()) { cout << "\n Durn, couldn't read image filename " << filename << endl; return 1; } const string winName = "image"; namedWindow(winName, WINDOW_AUTOSIZE); setMouseCallback(winName, on_mouse, 0); gcapp.setImageAndWinName(image, winName); gcapp.showImage(); for (;;) { char c = (char)waitKey(0); switch (c) { case '\x1b': cout << "Exiting ..." << endl; goto exit_main; case 'r': cout << endl; gcapp.reset(); gcapp.showImage(); break; case 'n': int iterCount = gcapp.getIterCount(); cout << "<" << iterCount << "... "; int newIterCount = gcapp.nextIter(); if (newIterCount > iterCount) { gcapp.showImage(); cout << iterCount << ">" << endl; } else cout << "rect must be determined>" << endl; break; } } exit_main: destroyWindow(winName); return 0; }随手操作一下，今日力竭，明天会进一步研究并补充。（to myself：及时总结哦！！！）
7月6日：研究grabCut示例程序。
参考：grabCut使用
1、运行界面： 解释一下最后四个参数：
GCD_BGD（=0），背景； GCD_FGD（=1），前景； GCD_PR_BGD（=2），可能的背景； GCD_PR_FGD（=3），可能的前景。依照上述含义进行兴趣部位的抓取：（只设置背景与前景，可能手法粗略了一些） 可以发现，提取的效果还可以。（应老师的建议，看看不同阴影角度的房屋提取的效果） 效果也的确可以接受。（肉眼可见一处错误，提取图像下方有一处应该是地面，由于颜色纹理相近被划分到屋顶）
可以参考这个：grabCut算法详解
