1. import processing.opengl.*;
2. PGraphics pg;
3. void setup() {
4.   size(800,800,OPENGL);
5.   pg = createGraphics(256, 256,P2D);
6. }
7. void draw() {
8.   pg.loadPixels();
9.   pg.updatePixels();
10.   image(pg,0,0);
11. }

Here is a very simple code for just testing, and it seems to be no problem in my view,

But this code makes an out of memory error.

My memory setting is 1600mb and this is maximum value in my system.

Why does this happens? Is it opengl error? Should I use another library for this?