Fade In/Fade Out of two images

fadeInOut.pde

PImage imgA, imgB;
float transparency;
float targetTransparency;
boolean isFadeAtoB;
boolean  isFadeCompleted;
int currentTime;
int fadeCompletedTime;
float easing;
void setup() {
  imgA = loadImage("a.jpg");
  imgB = loadImage("b.jpg");
  size(imgA.width, imgA.height);
  isFadeAtoB = true;
  transparency = 0;
  targetTransparency = 255;
  isFadeCompleted = false;
  easing = 0.02;
}

void draw() {
  background(255);
  if(targetTransparency - transparency <= 1.0) {
    currentTime = millis();
    if(isFadeCompleted) {
      if(currentTime - fadeCompletedTime >= 5000) {
        transparency = 0;
        isFadeAtoB = !isFadeAtoB;
        isFadeCompleted = false;
      }
    } else {
      isFadeCompleted = true;
      fadeCompletedTime = currentTime;
    }
  }

  if(isFadeAtoB) {
    noTint();
    image(imgA, 0, 0);
    tint(255, transparency);
    image(imgB, 0, 0);
  } else {
    noTint();
    image(imgB, 0, 0);
    tint(255, transparency);
    image(imgA, 0, 0);
  }

  transparency += (targetTransparency - transparency) * easing;
}