在目标光和背景光的照射下，呈现出一组同心圆环，其亮度与目标和背景的亮度成正比。
The ring sight presents a set of concentric rings when it is illuminated by the target and the background. Brightness of the rings is in proportion to that of the target and the background.
最好的信号不仅取决于它的亮度，还取决于它与背景的对比度。
The best signal depends not only on its brightness but also on how well it contrasts with the background against which it must be seen.
深色可以给火焰增加亮度，而且要确保你的注意力在火焰本身上，保持背景的简单是很重要的。
A dark color adds intensity to the fire and keeping the background simple to begin with is important to ensure that you concentrate on the fire itself.
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