1. void setup() {
     size(500, 500);
     background(25);
     //
     stroke(225, 240, 255);
     for (int i=0; i<400; i++) {
       point(i, 20);
     }
   line(0,22, 399,22);
   //
     stroke(225, 240, 255, 75);
     for (int i=0; i<400; i++) {
       point(i, 40);
     }
   line(0,42, 399,42);
   }
   

1. //====================
   class ArrayInt2 {
     //assuming same length arrays
     int[] a;
     int[] b;
     int len;
2.   ArrayInt2(int n) {
       a=new int[n];
       b=new int[n];
       len=n;
     }
     ArrayInt2(int[] a0, int[] b0) {
       //assuming same length (a0, b0)
       len=a0.length;
       a=new int[len];
       b=new int[len];
       for (int i=0; i<len; i++) {
         a[i]=a0[i];
         b[i]=b0[i];
       }
     }
     ArrayInt2(ArrayInt2 ai2) {
       int[] a0=ai2.a;
       int[] b0=ai2.b;
       len=a0.length;
       a=new int[len];
       b=new int[len];
       for (int i=0; i<len; i++) {
         a[i]=a0[i];
         b[i]=b0[i];
       }
     }
     ArrayInt2 toCopy() {
       int[] a0=new int[len];
       int[] b0=new int[len];
       for (int i=0; i<len; i++) {
         a0[i]=a[i];
         b0[i]=b[i];
       }
       ArrayInt2 k=new ArrayInt2(a0,b0);
       return k;
     }
     ArrayInt2 toCopy() {
       ArrayInt2 k=new ArrayInt2(a,b);
       return k;
     }
   }//class ArrayInt2
   

1. void setup() {
     size(577,594); // <<<< to be modified according to img LoadImage size
     npix=width*height;
     setupImage();
   }//setup()
2. void setupImage() {
     background(255);
     smooth();
     img=loadImage("gridQuad 120409-045813a.png"); //<<<< image source
     image(img, 0, 0);
   }//setupImage()
   

How should I make a loop to make/display/save all successive images?

Here is what I mean.
My program has this structure:
- setup display an initial image,
- draw does nothing at all,
- keyPressed() modifies the image (according to the key I pressed),
- mousePressed saves it when I want.

setup(){
...
}

draw() {
}

void keyPressed() {
  switch (key) {
   ...
  }
}

void mousePressed() {
    save(fname);
}

Now, I would like also to be able to do all keyPressed and save automatically.
I mean instead of pressing 'a' then save, then pressing 'b' then save, etc...,
I would like to generate and save all images.
But a loop inside keyPressed won't work cause the display is only updated after draw().
I try using redraw() inside such a loop, but it doesn't seems to work.

Any suggestion?