Blob tracking

Now that you know how to apply a thresholding algorithm on a webcam feed, it's time to do some analysis on those pixels. We'll draw a rectangle around all white pixels in the image. This is a very basic brightness tracking algorithm and is useful when you want to create a simple interactive installation with a webcam.

How to do it...

We'll start by importing the video library and declaring some variables. We need a Capture object to access the webcam and an integer variable to use as a threshold value. The other integer variables are used to track the boundaries around the white pixels in the image.

import processing.video.*;
  
Capture webcam;
int threshold;
  
int topLeftX;
int topLeftY;
int bottomRightX;
int bottomRightY;
  
void setup()
{
  size( 640, 480 );

  webcam = new Capture( this, width, height, 30);
  webcam.start();
  
  threshold = 127;

  topLeftX = width;
  topLeftY = height;

  bottomRightX = 0;
  bottomRightY = 0;
}

Inside the draw() function, we'll apply the...