Jorge Pereira's profile - activity

I already cropped the image, I want to resize the row lenght as the example in the image. I have to perform those modifications (c to d).

It doesn't... I have this image witch is a Mat with different row size and I want to stretch the rows to make them of constant length.

I'm trying to resize the rows of a ROI Mat, witch is a polygon with different row size, to the half of the cols of the original Mat, and so I thought of run through all the rows of the Roi Mat and resize each one.

for (int j = 0; j < crop.rows; j++)
{
    if(pointPolygonTest( contours[0], Point2f((float)i,(float)j), true) > 0)

    //resize(crop.row(j), crop.row(j), Size(img.rows, img.cols/2), 0, 0, CV_INTER_LINEAR);
}

What am I doing wrong? Thank you!

no one?...

Hi, I have the left side image and I want to stretch the rows in order to obtain the right side image.

APPROACH 1:

This code (from here), gives me the contours.

vector< vector<Point> > contours;
contours.push_back(contour);

// you could also reuse img1 here
Mat mask = Mat::zeros(poseNormImg.rows, poseNormImg.cols, CV_8UC1);

// CV_FILLED fills the connected components found
drawContours(mask, contours, -1, Scalar(255), CV_FILLED);

// let's create a new image now
Mat crop(poseNormImg.rows, poseNormImg.cols, CV_8UC3);

// set background to green
crop.setTo(Scalar(255,255,0));

// and copy the magic apple
poseNormImg.copyTo(crop, mask);

imshow("cropped", crop);

How can I stretch the image from the contours, since it is a polygon with 10 points and and not a rectangle?

APPROACH 2:

Based on this question, I implemented this function , witch allow me to stretch a rectangle.

/**
 * http://stackoverflow.com/questions/7838487/executing-cvwarpperspective-for-a-fake-deskewing-on-a-set-of-cvpoint
 */
Mat deskewing(Mat src, Point pt1, Point pt2, Point pt3, Point pt4)
{
    vector<Point> not_a_rect_shape;
    not_a_rect_shape.push_back(pt1);
    not_a_rect_shape.push_back(pt2);
    not_a_rect_shape.push_back(pt3);
    not_a_rect_shape.push_back(pt4);

    // Assemble a rotated rectangle out of that info
    RotatedRect box = minAreaRect(cv::Mat(not_a_rect_shape));
    std::cout << "Rotated box set to (" << box.boundingRect().x << "," << box.boundingRect().y << ") " << box.size.width << "x" << box.size.height << std::endl;

    Point2f pts[4];

    box.points(pts);

    cv::Point2f src_vertices[3];
    src_vertices[0] = pts[0];
    src_vertices[1] = pts[1];
    src_vertices[2] = pts[3];

    Point2f dst_vertices[4];
    dst_vertices[0] = Point(0, 0);
    dst_vertices[1] = Point(box.boundingRect().width-1, 0); // Bug was: had mistakenly switched these 2 parameters
    dst_vertices[2] = Point(0, box.boundingRect().height-1);
    dst_vertices[3] = Point(box.boundingRect().width-1, box.boundingRect().height-1);


    Mat warpAffineMatrix = getAffineTransform(src_vertices, dst_vertices);

    cv::Mat rotated;
    cv::Size size(src.cols/2/*box.boundingRect().width*/, box.boundingRect().height);
    warpAffine(src, rotated, warpAffineMatrix, size, INTER_LINEAR, BORDER_CONSTANT);

    return rotated;
}

Since I was not able to stretch the entire polygon sub matrix, I thought of decomposing the polygon in to rectangles, stretching those areas and then sum them.

Using this approach I have two problems: the rectangle area is re sized to min area and rotated.

Is this the correct approach or is there another way?

Thank you

It was just an alternative, no need for down vote.

With this code I was able to get the left side! How can I obtain the right one?...

    std::vector<Point> contour;
    Mat roi(poseNormImg.rows, poseNormImg.cols, CV_8UC1);

    contour.push_back(normImgTop);
    contour.push_back(normImgEyebrowInner);
    contour.push_back(normImgCNoseTip);
    contour.push_back(normImgCNoseBase);
    contour.push_back(normImgTopLip);
    contour.push_back(normImgDownLip);
    contour.push_back(normImgTipOfChin);
    contour.push_back(normImgBottom);
    contour.push_back(normImgBottomRight);
    contour.push_back(normImgTopRight);

    vector< vector<Point> > contours;

    contours.push_back(contour);

    // draw the polygon
    polylines(roi, contours, true, Scalar(255), CV_AA);

    Mat mask = c

Hi, thank you for your answer. This codes gives me the same result, "just" the draw. Do you know how can I convert it to a Mat?

Hi, I already have submatrixs obtained like that, the problem is that this submatrix is not a rectangle, its a polygon.

Hi, I had several problems with Windows x64 and decided to change to Linux Mint (x64). I followed this tutorial and was able to install the latest version of OpenCv.

Hi, thank you for your answer. I rephrased my question and added some code.

Hi, my objective is to obtain the right side of this image.

I thought I'd see the image as a polygon because I have the coordinates of the vertices, and then transform the vector that has the vertices in a matrix (cvMat).

My thought is correct or is there a simpler way to get this submatrix?

With the following code I can draw the polygon but I need to convert it to a matrix.

Point normImgTop, normImgEyebrowInner, normImgCNoseTip, normImgCNoseBase, normImgTipOfChin, normImgTopLip, normImgDownLip, normImgBottom, normImgTopRight, normImgBottomRight;

(...)

        std::vector<Point> contour;
        Mat roi(poseNormImg.rows, poseNormImg.cols, CV_8UC1);

        contour.push_back(normImgTop);
        contour.push_back(normImgEyebrowInner);
        contour.push_back(normImgCNoseTip);
        contour.push_back(normImgCNoseBase);
        contour.push_back(normImgTopLip);
        contour.push_back(normImgDownLip);
        contour.push_back(normImgTipOfChin);
        contour.push_back(normImgBottom);
        contour.push_back(normImgBottomRight);
        contour.push_back(normImgTopRight);

        const cv::Point *pts = (const cv::Point*) Mat(contour).data;
        int npts = Mat(contour).rows;
        std::cout << "Number of polygon vertices: " << npts << std::endl;

        // draw the polygon
        polylines(roi, &pts,&npts, 1,
                            true,           // draw closed contour (i.e. joint end to start)
                            Scalar(0,255,0),// colour RGB ordering (here = green)
                            3,              // line thickness
                            CV_AA, 0);

I'm using OpenCV 2.4.6.1 and C++.

Thank you