动物主要借助网膜中的两类光感细胞获得视觉：视杆细胞帮助感知亮度，而种类众多的视锥细胞则帮助辨别颜色。

Retinas use two main types of light-sensitive cells to allow animals to see: Rod cells help measure brightness, while various types of cone cells help distinguish colors.

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大气状况和观察者的视觉灵敏度也会降低边缘亮度。

Atmospheric conditions and the visual acuity of the observer will often reduce limiting magnitude.

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研究道路照明应以更加符合人眼视觉特性的亮度指标和可见度指标对道路照明质量进行评价。

The research on the appraisal to the road lighting quality should use luminance standard and small target visibility level which are more conform to the human eye visual characteristic.

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