Afaik imgen ai starts with a salt and pepper noise image (randomised grey values, or maybe even randomised colour values). It then pushes and pulls the image in the direction of its learned nodes and weights.

So typically an imgen ai will generate images with a very even distribution of value (light and dark). It will have difficulty generating a picture like a Rembrandt painting with high light/dark contrasts. It probably can’t generate pictures with a lot of dark and one small bright spot. At least not out of the box.