A.R Drone 2.0 Object Recognition

Question

I am trying to do some image processing and I wanted to know if using color filtering or object detection is a better method for real time streaming. I am using node.js for programming purposes and node-dronestream as my streaming module. I want to use opencv for the image processing but not sure how to approach this task. I want the drone to simply follow a gutter autonomously by following a line. So I want the drone to find the gutter and somehow perform its task by cleaning out leaves or any debris in the gutter. I have the codes for node.js and the streaming module shown below.I know its not much but I am not sure how to opencv for the image processing part.The picture of the gutter is attached.

var arDrone = require('ar-drone');
var client  = arDrone.createClient();

client.takeoff();

client
      .after(2000, function() {
        this.up(1);
      })
      .after(5000, function() {
        this.front(1.0);
      })
      .after(2000, function() {
        this.clockwise(0.5);
      })
      .after(5000, function() {
        this.back(0.8);
      })
      .after(2000, function() {
        this.land();
      });

var http = require("http"),
    drone = require("../../index");

var server = http.createServer(function(req, res) {
  require("fs").createReadStream(__dirname + "/index.html").pipe(res);
});

drone.listen(server);
server.listen(5555);