optical opacity

1. The degree of optical opacity of a medium or material, As of a photographic negative.
   一定介质或材料（例如照相感光纸）的不透光程度。
2. In addition to value, hue and chroma, there are many subtle secondary optical properties of natural human tooth, such as translucency, opacity, iridescence, surface gloss and fluorescence.
   天然牙的视觉外观除了颜色的三要素色相、明度、饱和度以外，还有许多第二光学特征：半透性、浑浊度、晕色、表面光泽度、荧光性，其中以半透性最为重要。
3. Transfer function will map the three-dimensional scalar data to optical imaging parameters, making each voxel to display the corresponding color and opacity, etc., showing the area we care about, hiding those we do not care about.
   传输函数将三维数据场的数据属性映射为光学成像参数，给每个要显示的体素相应的颜色和不透明度等，来显示我们关心的区域，隐藏那些我们不关心的区域。

noun

1. opacity to light