int N = 400;

size(N, N);

for (int x=0; x < N; x++) {
  for (int y=0; y < N; y++) {
    float percentX = 1.0 * x / N;
    float percentY = 1.0 * y / N;
    float percentDiff = abs(percentX-percentY);
    stroke(255*(1-percentY), 255*percentDiff, 255*(1-percentX));
    point(x, y);
  }
}


save("colorMix3.jpg");