Letters getting swallowed

void setup() {
  size(500, 400);
  background(0);
  stroke(255);
  fill(255);
  textSize(80);
}
void draw() {
  fill(0,15);
  rect(0,0,width, height);
  fill(255);
  if (frameCount < 40) {
    text(char(int(random(65, 90))), random(75, 425), random(75, 325));
  }
  filter(BLUR, 3);
  filter(THRESHOLD);
  filter(BLUR);
}