There is an error in the following code.
At first all three loops are executed, but in the second run of the outer loop the middle loop in line 6 isnt executed.
The error message is:
Exception in thread "Animation Thread" java.lang.NullPointerException
        at processing.Main.getColor(Main.java:87)
        at processing.Main.setup(Main.java:46)
        at processing.core.PApplet.handleDraw(Unknown Source)
        at processing.core.PApplet.run(Unknown Source)
        at java.lang.Thread.run(Thread.java:619)

1. private int[] getColor(PImage[] pics) {
2.   long[] color = new long[pics.length];
3.   int[] c = {0};
4.   for(int i = 0; i < pics.length; i++) {         //Schleife geht einzelne Bilder durch
5.     println("i = " + i);
6.     for(int x = 0; x < pics[i].width; x++) {         //2 Schleifen für die beiden Bildachsen
7.       println("x = " + x);
8.       for(int y = 0; y < pics[i].height; y++) {
9.          println("y = " + y);
10.          color[i] = color[i] + (long) red(pics[i].get(x, y));
11.          println("color[i] = " + color[i]);
12.       }
13.     }
14.     color[i] = color[i] / (pics[i].width * pics[i].height);     //Aus Summe wird der Durchschnitt berechnet.
15.     println("Durchshnitt: color[i] = " + color[i] + ", " + col);
16.   }
17.   for(int i = 0; i < color.length; i++) {
18.     c[i] = (int) color[i];
19.      println("c[i] = " + c[i]);
20.   }
21.   return c;
22.   }

Can someone tell me, whats wrong with it? Ive been looking the whole day to find the mistake. So please help me.