映射（调色）Mapping

调色的本质是给每个像素的数值套一个映射：(R, G, B) → (R′, G′, B′)。

• 轮子、曲线、色条都是函数：界面不同，做的都是同一件事——改数值的走向。
• LUT 是预算好的映射表：三维查找表，只查表、不判断（见 LUT（查找表））。
• 顺序有讲究：一串函数组合，顺序不同、结果不同——同一个 LUT 放前放后完全两样。
• 色彩管理决定解释：数值在哪个色彩空间被解释，也是映射的一部分（见 色彩管理）。

Grading, at its core, applies a mapping to every pixel's numbers: (R, G, B) → (R′, G′, B′).

• Wheels, curves and bars are all functions: different interfaces for one thing — steering the numbers.
• A LUT is a precomputed mapping table: a 3D lookup table that only looks up, never judges (see LUT).
• Order matters: a chain of composed functions — different order, different result; the same LUT before vs after is a different picture.
• Color management decides interpretation: in which color space the numbers are read is part of the mapping too (see Color Management).