diegomez_86's profile - activity

Hello. I have an image loaded from cv2 (I cannot load it in cv directly because I have to use ROS on it and it just has conversion to cv2) and I need to convert it to cv in order to later write it as a YAML file. Does anyone know how to do it? I looked on internet for several options, but until now I see just how to write a YAML only from cv or how to load a YAML file in as an opencv Mat. I also found several help but in c++ (and I have to work on a python script)

If someone knows how to do it and can tell me the procedure, I would be very thankful to you guys.

Hello, Does anyone know how to save, write, convert, etc an Opencv Mat into a YAML file using python?

I tried with cv.Save but it tells me "Cannot identify type of 'structPtr'", and with ImWrite it tells me error: "(-2) could not find a writer for the specified extension in function imwrite"

Thanks a lot for your help.

Hi, and thanks. I already did it. and solved it with split as you said... Actually it was pretty easy. I didn't have to cope with all of those questions cause OpenCV did the job for me.

Hello Everyone, I want to dividide a BGR image into 3 images containing the 3 different CIE Lab color components (with just one channel). I know that I can do something like this:

 #include <opencv2/opencv.hpp>

 using namespace std;
 using namespace cv;

 int main( int argc, char** argv )
 {
      Mat src = imread( "/home/diego/Documents/sunset.jpg", -1 ), lab;
      cvtColor(src, lab, CV_BGR2Lab);
      imshow("lab", lab);
      return 0;
 }

And this gives me a kind of result like this

However I read something that tells me that I need to treat the Luminance between 0 and 100, and a,b with values between -127 to 127 (So I don't know if this image is right or wrong). I would like to ask what is meant with these values... are these ones the pixel values, are these ones normalized values from the original 0 to 255? Are the values of this 3 channel image representing L((lab[0]), A(lab[1]), and B(lab[2])?

I have checked in several webpages to give me an idea but I just see very theoretical information about how the 3 axis Lab color space is composed but nothing that I can convert into real things.

Thanks and sorry for so many questions.

I don't know if it worked for @zulfiqar to me it doesn't do it...

Hello Everyone

I am working on a spin the bottle game with OpenCV and a robot NAO. I already made a program to draw a line projecting to the pointing place of the bottle but in 2d (the robot can see just the bottle in a white background) now I would like with opencv to project that line into the 3d space in order to find a person which the bottle points to.

I am not sure how or where to start. I found something with camera calibration, Pose estimation and Depth Map from Stereo Images. Could you guys please help me with information or topics where I could start reading or doing something from OpenCV?

Thanks

Hello, actually I am doing the orientation of a bottle and using fitEllipse for this... Could you please explain me what you mean with restrict the angle?... Perhaps I could help you :)

Thanks @StevenPuttermans. Then I think I will keep converting the vectors to to Mat then.

@theodore (or anyone who can answer this to me), I forgot to ask something about your code

In these 2 lines I saw that you converted the vectors of points into a matrices. Does it have any convenience for the program or does it produce better results? I tried with just the vectors of points pluse different images (20) and there was no difference (in the image, I don't know about the structure) in the results

 cv::convexHull(cv::Mat(merged_contour_points),hull);
 cv::RotatedRect minEllipse = fitEllipse(hull_points); //

Thanks in advance for your answer

Wow, @theodore, Thanks for your help... it's awesome. Now I will look more at convex hull.

Hello everybody

I am trying to draw an ellipse based on some points that I assign from a Threshold in an image. This is the image

I used fitEllipse function with parameter, all of the points of all of the pixels in a vector of points, with this I thought I was going to get an ellipse in the center of the image, however I got this one

I would like to get something like this (of course it should be an ellipse, but I'm not an expert in graphical design with paint) in a way of ellipse or if it was possible to get a RotatedRect square like this, then it would be awesome too.

I also tried with contours, however the result is not also that good.

I would like your help guys. this is the code I am using

#include <opencv2/opencv.hpp>
using namespace cv;
using namespace std;
double thresholdValue = 0;

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

Mat src = imread( "/home/diego/Humanoids/imageGreen0.png", 1 );
Mat imageGreen = Mat::zeros(src.size(), CV_8UC1), threshold_output;
Vec3b result;

for (int i = 0; i < src.rows ; i++)
{
    for (int j = 0; j < src.cols ; j++)
    {
        result = src.at<cv::Vec3b>(i,j);
        int value = result[1];
        imageGreen.at<uchar>(i, j) = value;
    }
}

threshold( imageGreen, threshold_output, thresholdValue, 255, THRESH_BINARY_INV );
vector<Point2f> pointsPixels;
for(int i = 0; i < src.rows; i++)
    for(int j = 0; j < src.cols; j++)
    {
        if((int)threshold_output.at<unsigned char>(i, j) == 255)
        {
            pointsPixels.push_back(Point(j,i));
        }
    }

RotatedRect elipseBottle = fitEllipse(pointsPixels);
ellipse(threshold_output, elipseBottle, Scalar(125), 2, 8 );
imshow("threshold ouput", threshold_output);

 return 0;
}

I would be very thankful to you if you guys could help me with a solution or at least ideas (by now I will keep checking at rotatedRect functions or fitEllipse in case I did something wrong). Thanks a lot.

Hello and thanks to LBerger who made me take into account the row, columns thing. This is the final code:

 #include <iostream>
 #include <stdio.h>
 #include <opencv2/opencv.hpp>
 using namespace cv;
 using namespace std;

 Mat imageGreen;

 static void onMouse(int event, int x, int y, int f, void*){
cout <<(int)imageGreen.at<unsigned char>(y, x) << endl;
 }

 int main(int argc, char** argv) {
Mat inputImage = imread("/home/diego/Humanoids/imageGreen0.png");
imageGreen = Mat::zeros(inputImage.size(), CV_8UC1);

   //Getting the green channel value and putting it into a one channel value.

Vec3b result;

for (int i = 0; i < inputImage.rows ; i++)
{
    for (int j = 0; j < inputImage.cols ; j++)
    {
        result = inputImage.at<cv::Vec3b>(i,j);
        int value = result[1];
        imageGreen.at<uchar>(i, j) = value;
    }
}

cout <<imageGreen.channels()<<endl;

namedWindow( "imageGreen", CV_WINDOW_NORMAL);
imshow("imageGreen", imageGreen);
setMouseCallback("imageGreen", onMouse, 0);
waitKey(0);
return 0;

}

Thanks for showing me, however I need the green value sent into a 1 channel Uchar mat. I tried the way you told me and it worked, however I want just one single value and use this procedure in order to find a way of getting rid of the bottle shadow (I am assuming that the bottle is green ). but now that I want to check at the value, the screen just disappears. I updated the new code into the question.

Thanks for what I just learned and sorry for the inconvenient.

Hello, I want to check pixel values with this program, however the results are not convincing at all for me. I am loading an image in grayscale and the colors are of course very different as it can be seen in the image

However when I pass the mouse (with the implemented mouse callback function) I receive white colors with values of 90 for example, or black colors with values of 130.

/*Updated algorithm. Now it doesn't show the values. the window disspaears like with an exception when the mouse is passed through the image"

#include <iostream>
#include <stdio.h>
#include <opencv2/opencv.hpp>
#include <highgui.h>

using namespace cv;
using namespace std;

Mat image, imageGreen;
char window_name[20]="Get coordinates";

static void onMouse( int event, int x, int y, int f, void* )
{       
    uchar intensity = imageGreen.at<uchar>(x,y);
cout << "x: "<< x << " y: " << y << endl << " value: " << (int)intensity << endl;
}

int main() {
    namedWindow( window_name, CV_WINDOW_NORMAL );
    image = imread("/home/diego/Humanoids/imageGreen0.png");
    Mat imageGreen = Mat::zeros(image.size(), CV_8UC1);
    Vec3b result;

    for (int i = 0; i < image.rows ; i++)
{
    for (int j = 0; j < image.cols ; j++)
    {
        result = image.at<cv::Vec3b>(i,j);
        int value = result[1];
        imageGreen.at<uchar>(i, j) = value;
    }
}

    cout<< "Image depth: "<<imageGreen.depth()<<" # of channels: "<<imageGreen.channels()<<"\n";
    imshow( window_name, imageGreen );
    setMouseCallback( window_name, onMouse, 0 );
    waitKey(0);
    return 0;
}

I want to learn how to use this because I want to get rid of the bottle shadow (by the way, here I put the green value of each pixel from an RGB image into the correspondent pixel in a grayscale image --> It's a green bottle) and I thought that maybe there can be a difference between the values of the bottle and the reflection from the sun which can allow me to make a threshold.

Can anyone help me telling me what is the error here? I am trying to stop being a newbie in OpenCV and C++, but I think that there is still a long way for it. Thank you

I changed the algorithm and now I'm using another image

You are awesome man. Thanks for the pre and post-processing ideas... I already used them on my program. Actually right now I'm just wanting to give an initial draft of the whole program (A Nao Robot playing spin the bottle game), later I will make more improvements and I will ask more from here.

This is the code

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"

#include <iostream>

using namespace cv;
using namespace std;

int main(int argc, char** argv)
{
 const char* filename = "/home/diego/Documents/frame0.jpg";

 Mat src = imread(filename, 0);

 Mat dst, cdst;
 Canny(src, dst, 100, 100, 3);
 cvtColor(dst, cdst, CV_GRAY2BGR);

  vector<Vec4i> lines;
  HoughLinesP(dst, lines, 1, CV_PI/180, 2, 50, 10 );
  for( size_t i = 0; i < lines.size(); i++ )
  {
    Vec4i l = lines[i];
    line( cdst, Point(l[0], l[1]), Point(l[2], l[3]), Scalar(0,0,255), 3, CV_AA);
  }

  imshow("original image", src);
  imshow("detected lines", cdst);

 waitKey();

 return 0;
}

Actually I am using CannyEdge + HoughLinesP

My idea is to find the orientation of the bottle. I tried with other options, actually there is an option to find the orientation of the bottle (Object orientation which appears in http://www.google.de/imgres?imgurl=ht...), however the shadow and reflect of the bottle affects the real orientation of it (So I would need to find an algorithm to detect them)

I will add the photos in my main question.

Hello everyone, I am trying to detect the straight lines in a bottle. I am using the example provided by OpenCV tutorials however the maximum I can get is just one.

I have played with most of the parameters of CannyEdge and Houghlinesp, however the maximum I can get is always maximum 1 (I got 2 but just in one example) I am sending the examples of bottles that I am trying also with it's resulting example.

I have several suspects about the problems with this non-detection: one could be the shadow, other one could be the light reflect, and even I am thinking that the camera is not well calibrated. However if someone knows or has worked with this function before and thinks that this doesn't have any relation, I would thank you too much.

Thanks a lot for everything.

!

The original images