I'm working on this and can't figure it out. I'm assuming it has something to do with the loadPixels(), get(), or pixels[] functions. Basically it's a background subtraction program that thresholds. I want to figure out the percentage of white pixels in the whole frame and print it in the console.

I'm assuming it's something along the lines of:

----------------------------------
 numPixels = video.width * video.height;
 backgroundPixels = new int[numPixels];

for (int i = 0; i < numPixels; i++) {
       get(i);
}

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I figured I'd just post to look for some help while I'm working on it.

Code:

import processing.video.*; 
int numPixels; 
int[] backgroundPixels; 
Capture video; 
 
void setup() { 
  // Change size to 320 x 240 if too slow at 640 x 480 
  size(640, 480);  
   
    String[] devices = Capture.list();

   
  video = new Capture(this, width, height, devices[1]); 
  numPixels = video.width * video.height; 
  // Create array to store the background image 
  backgroundPixels = new int[numPixels]; 
  // Make the pixels[] array available for direct manipulation 
  loadPixels(); 
} 
 
void draw() { 
  if (video.available()) { 
    video.read(); // Read a new video frame 
    video.loadPixels(); // Make the pixels of video available 
    // Difference between the current frame and the stored background 
    int presenceSum = 0; 
    for (int i = 0; i < numPixels; i++) { // For each pixel in the video frame... 
 // Fetch the current color in that location, and also the color 
 // of the background in that spot 
 color currColor = video.pixels[i]; 
 color bkgdColor = backgroundPixels[i]; 
 // Extract the red, green, and blue components of the current pixelÕs color 
 int currR = (currColor >> 16) & 0xFF; 
 int currG = (currColor >> 8) & 0xFF; 
 int currB = currColor & 0xFF; 
 // Extract the red, green, and blue components of the background pixelÕs color 
 int bkgdR = (bkgdColor >> 16) & 0xFF; 
 int bkgdG = (bkgdColor >> 8) & 0xFF; 
 int bkgdB = bkgdColor & 0xFF; 
 // Compute the difference of the red, green, and blue values 
 int diffR = abs(currR - bkgdR); 
 int diffG = abs(currG - bkgdG); 
 int diffB = abs(currB - bkgdB); 
 // Add these differences to the running tally 
 presenceSum += diffR + diffG + diffB; 
 // Render the difference image to the screen 
  
 // This is the change I've made: 
 int threshold = 65; 
  
 pixels[i] = (diffR + diffG + diffB) > threshold ? color(255) : color(0); 
  
 // the ? : stuff if you haven't seen it before means -> (is it like this)? yes : no; 
 // Because a web cam image tends to be grainy, it means that what we get isn't so clear 
 // cut as we would expect - so you use a threshold value to tweak for the output you want 
  
    } 
    updatePixels(); // Notify that the pixels[] array has changed 
    println(presenceSum); // Print out the total amount of movement 
  } 
} 
 
// When a key is pressed, capture the background image into the backgroundPixels 
// buffer, by copying each of the current frameÕs pixels into it. 
void keyPressed() { 
  video.loadPixels(); 
  arraycopy(video.pixels, backgroundPixels); 
} 
 

Note: I'm using an external isight. If you have a built in isight, change:
video = new Capture(this, width, height, devices[1]);
to
video = new Capture(this, width, height, 24);