从python中的BackgroundSubtractorMOG2获取背景模型

Question

我需要使用opencv获得高斯混合的背景模型.我知道在C++中有一个名为getBackgroundImage的方法我搜索了是否可以在python接口中获取它但我没有得到好的结果.我试过opencv 3.0.0-dev因为它有BackgroundSubtractorMOG2实现,但是help()函数没有为背景模型记录方法实现.你知道是否有无证实施？我搜索了如何编辑opencv源来实现python实现,但我还没有找到有关它的文档.我更喜欢避免使用scipy.weave来编译c ++代码,而且我不知道scipy.weave在这种情况下是否有用

Answer 1

Zaw Lin在Ubuntu 12.04中的解决方案:

主要区别在于结果(fg/ bg)图像是在python中创建/分配的,然后传递给c ++ lib.Zaw Lin的解决方案给了我错误(错误139 - SIG_SEGV),因为应用程序正在访问无效的内存区域.希望它能节省几个小时:)

mog2.cpp:

#include <opencv2/opencv.hpp>

cv::BackgroundSubtractorMOG2 mog(100, 16, false);

extern "C" void getfg(int rows, int cols, unsigned char* imgData,
        unsigned char *fgD) {
    cv::Mat img(rows, cols, CV_8UC3, (void *) imgData);
    cv::Mat fg(rows, cols, CV_8UC1, fgD);
    mog(img, fg);
}

extern "C" void getbg(int rows, int cols, unsigned char *bgD) {
    cv::Mat bg = cv::Mat(rows, cols, CV_8UC3, bgD);
    mog.getBackgroundImage(bg);
}

编译它像:

gcc -shared -o libmog2.so -fPIC ./mog2.cpp -lopencv_core -lopencv_highgui -lopencv_objdetect -lopencv_imgproc -lopencv_features2d -lopencv_ml -lopencv_calib3d -lopencv_contrib -lopencv_video

然后是python:

mog2.py

import numpy as np
import ctypes as C
import cv2

libmog = C.cdll.LoadLibrary('path/to/libmog2.so')

def getfg(img):
    (rows, cols) = (img.shape[0], img.shape[1])
    res = np.zeros(dtype=np.uint8, shape=(rows, cols))
    libmog.getfg(img.shape[0], img.shape[1],
                       img.ctypes.data_as(C.POINTER(C.c_ubyte)),
                       res.ctypes.data_as(C.POINTER(C.c_ubyte)))
    return res


def getbg(img):
    (rows, cols) = (img.shape[0], img.shape[1])
    res = np.zeros(dtype=np.uint8, shape=(rows, cols, 3))

    libmog.getbg(rows, cols, res.ctypes.data_as(C.POINTER(C.c_ubyte)))
    return res


if __name__ == '__main__':
    c = cv2.VideoCapture(0)
    while 1:
        _, f = c.read()
        cv2.imshow('f', f)
        cv2.imshow('fg', getfg(f))
        cv2.imshow('bg', getbg(f))
        if cv2.waitKey(1) == 27:
            exit(0)

Answer 2

这是一个使用 ctypes 的简单包装器，我只在 Windows 上测试过

cpp，构建为dll

#include "opencv2/opencv.hpp"
cv::BackgroundSubtractorMOG2 mog(100, 16, false);

cv::Mat bg;
cv::Mat fg;
extern "C" __declspec(dllexport)  unsigned char*  getfg(int rows,int cols, unsigned char* fdata)
{
    cv::Mat frame= cv::Mat(rows, cols, CV_8UC3,fdata);
    mog(frame,fg);
    //check fg.iscont(), copy as needed
    return fg.data;
}


extern "C" __declspec(dllexport)   unsigned char*  getbg()
{
    mog.getBackgroundImage(bg);
    return bg.data;
}

Python

import cv2
import numpy as np
import ctypes as C
lib = C.cdll.LoadLibrary('wrapper.dll')

def getfg(img):
    ptr = lib.getfg(img.shape[0],img.shape[1],img.ctypes.data_as(C.POINTER(C.c_ubyte)))

    buf = (C.c_ubyte * img.shape[0] * img.shape[1]  * 1).from_address(ptr)
    res = np.ndarray(buffer=buf, dtype=np.uint8,
                       shape=(img.shape[0], img.shape[1], 1))
    return res

def getbg(img):
    ptr = lib.getbg()
    buf = (C.c_ubyte * img.shape[0] * img.shape[1]  * 3).from_address(ptr)
    res = np.ndarray(buffer=buf, dtype=np.uint8,
                       shape=(img.shape[0], img.shape[1], 3))
    return res

c = cv2.VideoCapture(0)
while(1):
    _,f = c.read()
    cv2.imshow('f',f)
    cv2.imshow('fg',getfg(f))
    cv2.imshow('bg',getbg(f))
    if cv2.waitKey(1)==27:
        exit(0)