i have a sketch based on the example from face detection library from bryan chung.

when the faces are detected an image replaces the face, but when they go from detected to undetected because of either glitch or people leaving the screen i need the picture to fade away or fade in so its more consistent

anybody have any ideas on how to do this?

thanks for the reply!
it sounds like a pretty good idea to use a timer, but since ive never done anything with a time im a little lost.

millis i know is a function from the reference so no trouble there.

lost time is probably a variable that stores the exact time a face is lost but how it gets this time i dont know, can you explain?

here is the code i use right now:
it is modified so that it switches the faces detected out with eachother.

Code:

void drawFace() {
  int k;
  int [][] res = face.getFaces();
  if (res.length>0) {
    for (int i=0;i<res.length;i++) {
	int x = res[i][0];
	int y = res[i][1];
	int w = res[i][2];
	int h = res[i][3];
//here starts the face image thing
	images[i] = get(res[i][0],res[i][1],res[i][2],res[i][3]);
     k=i;
//here starts the face switching thing
     if(res.length==1){
	 image(images[i],res[i][0],res[i][1],res[i][2],res[i][3]);
	 println("one face");
     }else{
	 k=k-1;
	 if(k>-1){
	  image(images[i],res[i-1][0],res[i-1][1],res[i-1][2],res[i-1][3]);
     }
     }    
    }
  }
} 

it was done pretty fast so it has not proven totally reliable yet.
anyway what you tell me to do sounds really easy to implement if there is only one face, but i cant figure out how to do it with several.