Although scientists believe an octopus is most likely color blind, Paul may still be able to see horizontal lines, as well as levels of brightness and object size.
尽管科学家认为章鱼多半色盲，但保罗也许仍保留了一些对水平线条、明亮度、物体大小的感应。
2
The distance to such an object can be worked out by comparing its apparent brightness with its known, absolute brightness.