Problem with perspective

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Hello evrybody

I'm trying to apply a perspective transform on an image but I doesn't worklike I would like. Since code and pictures are easier to understand than a long speech (and because my english is quite poor) here is the code (in C):

#include <stdio.h>
#include "opencv/highgui.h"
#include "opencv/cv.h"


int main() {

    int flags;
    CvScalar fillval;
    CvPoint2D32f P[3], Q[3];

     IplImage *image, *resultat;
     CvMat* matrice = cvCreateMat(3,3,CV_32FC1);


    cvNamedWindow("Entrée", CV_WINDOW_AUTOSIZE);
    cvNamedWindow("Résultat", CV_WINDOW_AUTOSIZE);

    image = cvLoadImage("C:\\Users\\Julien\\Pictures\\tennis-3d.jpg", CV_LOAD_IMAGE_COLOR);
    resultat=cvCloneImage(image);
    cvShowImage( "Entrée", image);
    cvShowImage( "Résultat", resultat);
    P[0].x=266;
    P[0].y=101;

    P[1].x=534;
    P[1].y=101;

    P[2].x=667;
    P[2].y=394;

    P[3].x=133;
    P[3].y=393;

    Q[0].x=0;
    Q[0].y=0;

    Q[1].x=image->width;
    Q[1].y=0;

    Q[2].x=image->width;
    Q[2].y=image->height;

    Q[3].x=0;
    Q[3].y=image->height;

cvGetPerspectiveTransform(P,Q,matrice);

cvWarpPerspective(image,resultat, matrice,flags=CV_WARP_FILL_OUTLIERS,fillval=cvScalarAll(0) );

cvShowImage( "Résultat", resultat);

    cvWaitKey(1000000);
    return 0;

}

And the result : The goal is to have a "top view" of the court

Thank you for your help

Sparrow