title: Find the plate rectangle in a given picture
body: <p>This is my original picture and i want to find the plate in order to search for the number plate in this rectangle instead of searching in whole picture<br>
  original image test_1.jpg:<br><br>
  <img src="https://i.stack.imgur.com/wUfTC.jpg" alt="enter image description here"></p>
  
  <p>using the following code in javacv: <br></p>
  
  <pre><code>IplImage originalImage = cvLoadImage("test_1.jpg");
  IplImage resultImage = IplImage.create(originalImage.width(),
                  originalImage.height(), IPL_DEPTH_8U, 1);
  cvCvtColor(originalImage, resultImage, CV_BGR2GRAY);
  cvAdaptiveThreshold(resultImage, resultImage, 255, CV_ADAPTIVE_THRESH_GAUSSIAN_C, CV_THRESH_BINARY_INV, 7, 7);
  cvSaveImage("test_2.jpg", resultImage);
  </code></pre>
  
  <p>The resultant picture is test_2.jpg looks like this:<br><br>
  <img src="https://i.stack.imgur.com/WSWBc.jpg" alt="enter image description here"></p>
  
  <p>and adding this code by giving thresholdImg the resultImg<br><br></p>
  
  <pre><code>static void findLines(IplImage thresholdImg)
  {
      IplImage dst;
      IplImage colorDst;
      dst = cvCreateImage(cvGetSize(thresholdImg), thresholdImg.depth(), 1);
      colorDst = cvCreateImage(cvGetSize(thresholdImg), thresholdImg.depth(), 3);    
      cvCanny(thresholdImg, dst, 100, 200, 3);
      CvSeq lines = new CvSeq();
      CvMemStorage storage = cvCreateMemStorage(100000); 
      cvSaveImage("test_3.jpg", dst);
  }
  </code></pre>
  
  <p>The resultant picture test_3.jpg : <br><br>
  <img src="https://i.stack.imgur.com/ENMQD.jpg" alt="enter image description here"></p>
  
  <p>Is there any picture of what i generated can be used for continuing my code in order to find the rectangle containing the plate in the image</p>