so, as you can guess from the subject of my new topic, i have searched so far projects that have been made using video and what i have found that i think will help in my project is this code:
((** The basic concept is, when somebody enters a black room, the camera(which will be connected to the computer) will recognize the figure, and then with the processing analyzing/understanding it, according to the height of the person, a musical instrument will be generated and be projected on the wall.
For example when a short man enters the room, a violin will appear on the wall, but if a tall man enters, a guitar or another musical instrument will be generated and projected.))

original code(you must have the files from the link below):
// trackerDiff.pde
//
// part of the project 'demographic data in augmented reality'
// http://digitaleinformationsarchitektur.m05.de
//
// 2003 michael zoellner
//

Tracker t;
boolean bgSet = false;
int tolerance;
float diff;
BImage diffImage, bgImage;

void setup()
{
 size(320,240);
 noFill();
 stroke(#FFFF00);
 background(0);
 beginVideo(320,240,25);
 tolerance = 20; // treshold.. rbg+-value
 diff = width/video.width; // relation between screensize and videosize

 // initialize the tracker
 t = new Tracker();
 t.Tracker(tolerance, video.width, video.height);
}

void loop()
{
 //background(0);
 image(video, 0, 0); // show video
 if (bgSet == true)
 {
   // compare the video image with the reference image
   // returns an array with x1, y1, x2, y2 (upper left and bottom right)
   int[] rectPoints = t.GetPixelDiff(video, bgImage, diff);

   // returns an image of this area with alpha channel
   diffImage = t.GetPixelDiffImg();
   
   // draw a rect in this area
   rect(rectPoints[0]*diff, rectPoints[1]*diff, (rectPoints[2]-rectPoints[0])*diff, (rectPoints[3]-rectPoints[1])*diff);
 }
}

void keyReleased()
{
 // make a shot of the background -> reference image
 bgImage = t.GetRefBackground(video);
 bgSet = true;
}

the previous thread is here by my fellowstudent so you can have a look.http://processing.org/discourse/yabb_beta/YaBB.cgi?board=Video;action=display;num=1162291585


Thanks in advance!!!