OpenCV绘制轮廓和裁剪

时间:2016-02-20 17:39:15

标签: c++ opencv

我是OpenCV的新手。首先,将物体放在白纸上,然后使用机器人相机拍摄照片。在下一步,我试图使用OpenCV(找到轮廓和绘制轮廓)提取放在白纸上的对象。我想将这个对象用于我的机器人项目。

示例图片:

example image

这是我尝试过的代码:

int main(int argc, char* argv[]){

    int largest_area=0;
    int largest_contour_index=0;
    Rect bounding_rect;

    // read the file from console
    Mat img0 = imread(argv[1], 1);

    Mat img1;
    cvtColor(img0, img1, CV_RGB2GRAY);

    // Canny filter
    Canny(img1, img1, 100, 200);

    // find the contours
    vector< vector<Point> > contours;
    findContours(img1, contours, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);

    printf("%ld\n", contours.size());

    for( size_t i = 0; i< contours.size(); i++ ) // iterate through each contour.
    {
        double area = contourArea(contours[i]);  //  Find the area of contour

        if(area > largest_area)
        {
            largest_area = area;
            largest_contour_index = i;               //Store the index of largest contour
            bounding_rect = boundingRect(contours[i]); // Find the bounding rectangle for biggest contour
        }
    }

    cout << "contour " << contours.size() << endl;
    cout << "largest contour " << largest_contour_index << endl;

    Scalar color = Scalar(0,0,255);
    drawContours(img0, contours, -1, color);

    Mat roi = Mat(img0, bounding_rect);

    // show the images
    imshow("result", img0);
    imshow("roi",roi);

    imwrite("result.png",roi);

    waitKey();
    return 0;
}

这将为照片中的所有对象绘制轮廓。但是如何才能在白纸上提取物体?例如,在这张图片中:

this image

我想从图像裁剪卡片,但我不知道如何继续。任何人都可以帮助我吗?

1 个答案:

答案 0 :(得分:1)

在源图像上应用ROI,如下所示:

Rect r=Rect(200,210,350,300)
/*create a rectangle of width 350 and height 300 with x=200 and y=210 as top-left vertex*/
Mat img_roi=src(r);

选择矩形的适当尺寸应从图像中删除白板外的区域