Hello all,

I am working on a color tracking program, which is fully functional, but now I need to only scan a middle strip of the image. I want to essentially have the program look at and recognize a horizontal strip of pixels of a given width (lets say 10) centered at y=height/2.

How?

Below is the working code that scans the entire image.

/**
* Color Tracking
* by Justin Brooks
*
*
* based on original code:
*   Brightness Tracking
*   by Golan Levin.
*
* Tracks the tracks pixel closest in color to specified color.
*/


import processing.video.*;

Capture video;

void setup() {
 size(640, 480); // Change size to 320 x 240 if too slow at 640 x 480
 // Uses the default video input, see the reference if this causes an error
 video = new Capture(this, width, height, 30);
 noStroke();
 smooth();


}

void draw() {

 if (video.available()) {
   video.read();
   image(video, 0, 0, width, height); // Draw the webcam video onto the screen
   int colorX = 0; // X-coordinate of the closest in color video pixel
   int colorY = 0; // Y-coordinate of the closest in color video pixel
   float closestColor = 10000; //we set this to be abritrarily large, once program runs, the first pixel it scans will be set to this value
   // Search for the closest in color pixel: For each row of pixels in the video image and
   // for each pixel in the yth row, compute each pixel's index in the video
   color colorRead=color(0,255,0); //this is the color we will be searching for
   video.loadPixels();
   int index = 0;



   for (int y = 0 ; y < height; y++) {
     for (int x = 0; x < video.width; x++) {
       // Get the color stored in the pixel
       color pixelValue = video.pixels[index];
       // Determine the color of the pixel
       float colorProximity = abs(red(pixelValue)-0)+abs(green(pixelValue)-255)+abs(blue(pixelValue)-0);
       // If that value is closer in color value than any previous, then store the
       // color proximity of that pixel, as well as its (x,y) location
       if (colorProximity < closestColor) {
         closestColor = colorProximity;
         colorY = y;
         colorX = x;
       }
       index++;
     }
   }

   //Draw the area in which we are scanning
   rectMode(CENTER);
   stroke(0);
   noFill();
   rect(width/2,height/2,50,50);

   // Draw a large, circle at the closest in value pixel
   fill(colorRead, 128); //it will fill the circle as the color you want.
   noStroke();
   ellipse(colorX, colorY, 50, 50);
 }
}

pedro,

thank you so much... i can now adjust the "thickness" of the scan.

your for() index was something that I had thought of previously, but would get the wrong locational values; presumably because the index was off.

could you please explain, or link to, why this throws off my initial index?

thanks again for your help!

thanks again! feel free to check out the code below. i am much on my way to finishing it! the only feature left to add is the ability to set the color to be tracked by a click on a pixel with my mouse.

Code:

/**
 * Color Tracking
 * by Justin Brooks
 *
 *
 * based on original code:
 *   Brightness Tracking 
 *   by Golan Levin. 
 * 
 * Tracks the tracks pixel closest in color to specified color.
 */


import processing.video.*;

Capture video;

void setup() {
  size(640, 480); // Change size to 320 x 240 if too slow at 640 x 480
  // Uses the default video input, see the reference if this causes an error
  video = new Capture(this, width, height, 30);
  noStroke();
  smooth();



}

void draw() {

  if (video.available()) {
    video.read();
    image(video, 0, 0, width, height); // Draw the webcam video onto the screen
    int colorX = 0; // X-coordinate of the closest in color video pixel
    int colorY = 0; // Y-coordinate of the closest in color video pixel
    float closestColor = 10000; //we set this to be abritrarily large, once program runs, the first pixel it scans will be set to this value
    // Search for the closest in color pixel: For each row of pixels in the video image and
    // for each pixel in the yth row, compute each pixel's index in the video
    video.loadPixels();
    color colorRead=color(0,255,0); //this is the color we will be searching for
    int index = 0;
    colorMode(RGB);
    int scanHeight=10; //how wide would you like to scan?
    index = ((((height/2) - (scanHeight/2)) * width) - 1); //set this for first index value
    color Getcolor=get(mouseX,mouseY);


    //getting color by mouse click
    if (mousePressed){ //if mouse is pressed, we show a different color cross hair and perform color catching action
      video.read();
      color Get = get(mouseX,mouseY);
      rectMode(CENTER);
      stroke(Getcolor);
      noFill();
      rect(mouseX,mouseY,52,52);
    }


    for(int y = ((height/2) - (scanHeight/2)); y < ((height/2) + (scanHeight/2)); y++){
      for (int x = 0; x < video.width; x++) {
        // Get the color stored in the pixel
        color pixelValue = video.pixels[index];
        // Determine the color of the pixel
        float colorProximity = abs(red(pixelValue)-red(colorRead))+abs(green(pixelValue)-green(colorRead))+abs(blue(pixelValue)-blue(colorRead));
        // If that value is closer in color value than any previous, then store the
        // color proximity of that pixel, as well as its (x,y) location
        if (colorProximity < closestColor) {
          closestColor = colorProximity;
          colorY = y;
          colorX = x;
        }
        index++;
      }
    }


    // Draw a large, circle at the closest in value pixel
    fill(colorRead, 128); //it will fill the circle as the color you want.
    noStroke();
    ellipse(colorX, colorY, 50, 50);
    
    //print the location of the color found
    print("X: ");
    println(colorX);
    print("Y: "); //this doesn't really matter, but doesn't slow the program.
    println(colorY);

    //mousing setup - we will draw a crosshairs on where the mouse is.
    rectMode(CENTER);
    stroke(0);
    noFill();
    rect(mouseX,mouseY,50,50);
    rect(mouseX,mouseY,5,5);

    //draw a rectangle around the area we are scanning
    rectMode(CENTER);
    stroke(255,3,239); //bright pink
    noFill();
    rect(width/2,height/2,width,scanHeight);


    //draw a rectangle in the bottom corner to show what color is being picked up by the mouse location of video feed
    stroke(0);
    fill(Getcolor);
    rect(width-45,height-45, 90,90);
  }
}