def merge_images(first_image, second_image, percentage):
    """Merge images.

    Args:
        first_image: numpy array, int32 - [height, width].
        second_image: numpy array, int32 - [height, width].
        percentage: float32.
            Percentage weight of first image.

    Returns:
        merged_image: new_image: numpy array, int32 - [height, width, 3].
    """
    merged_image = first_image * percentage + second_image * (1 - percentage)
    return merged_image