(绘画的)明暗处理;(地图、图表等中)颜色浓淡强调某些部分的运用the use of colour, pencil lines, etc. to give an impression of light and shade in a picture or to emphasize areas of a map, diagram, etc.
2.
[pl]
(同一事物不同层面之间的)细微差别slight differences that exist between different aspects of the same thing