视觉密度 meaning in Chinese

visual density

Verification regulation of diffuse transmission visual densitometer
漫透射视觉密度计检定规程
Test method for specific optical density of smoke generated by solid materials
通过固体材料对烟雾产生的特定视觉密度的试验方法
Micrographics - duplicating film , silver , diazo and vesicular - visual density - specifications and measurement
缩微摄影技术银盐重氮和微泡拷贝片视觉密度技术规范和测量