contrast&balance 中文意思大概是（照片）对比度,但英英翻译,用英语怎么翻译?

Contrast is the difference between the color or shading of the printed material on a document and the background on which it is printed.
Balance is a desirable point between two or more opposite forces.balance的意思不是很清楚，它中文是翻译成什么？contrast和balance是分开来说的吗？