英语翻译

英语翻译
The outlined edges of four rectangles modulate in contrast as compared with the centers.In the top row,the centers of the rectangle are unchanging,but the top-bottom versus left-right edges modulate in counter-phase brightness,rendering the appearance of two breathing boxes.The second row proves that this effect is due to the contrast of the centers to the edges,and not to the brightness of the edges alone,because the edges are now unchanging,and only the centers of the rectangles modulate in brightness.