title: Shape detection javascript canvas
body: <p>I am doing a web application where i am pulling in an image from an IP camera, and I need to be able to see if there is a car in the parking spot. I wanted to do this using some sort of shape detection but all I can seem to find is face detection port from c++ and basic shapes such as squares. Can someone point me in the right direction so I can make my own shape detection?<img src="https://i.stack.imgur.com/wdwzD.jpg" alt="snapshot of cam">
   Right now I am drawing the blue box  and getting the images data for the x,y,h,w and seeing if I can get any other colors besides the 0xFFFFFF of the parking lot but it doesnt work at night at it will be skewed for humans walking.</p>
  
  <p>Any help would be appreciated..</p>
  
  <pre><code>function drawgrid(){
    context.drawImage(img, 0, 0);
    localStorage.setItem( "savedImageData", canvas.toDataURL("image/png") );
    context.beginPath();
    context.rect(308, 240, 250, 100);
    context.lineWidth = 2;
    context.strokeStyle = 'blue';
    context.stroke();
    var dataURL = canvas.toDataURL();
  }
  </code></pre>
  
  <p>this is grabbing image data saving it to local storage where I then loop through every pixel, however I don't think this is the correct way of going about it.</p>