黑白Luma Matte过渡

black and white video luma matte transition. The video starts with a completely black screen. From the center, white swirls emerge, resembling water or ink spreading outwards. These swirls grow and expand, flowing in a circular motion, gradually covering more of the screen. The white areas continue to spread and merge until they completely cover the black background, ending with a fully white screen. The transition should be smooth and fluid