Log · 灰片是在替你存动态范围Log · Flat means packed, not broken

难度LEVELL2 · 进阶L2 · Intermediate 领域TOPIC调色

先学：Prerequisites: 动态范围与亮度 色深 · 色彩精度

学习目标LEARNING OBJECTIVES

学完你能说清 Log 画面为什么灰、它替你存了什么，以及拿到 Log 素材第一步该做什么。

概念说明CONCEPTS

Log 是一种打包方式：把超出容器的大动态范围压进有限的位深里，代价是画面看起来灰、对比低。

  • 灰是特性不是病——高光和暗部的信息都被留着，只是暂时不显示给你看
  • 常见家族——Sony S-Log3、Canon C-Log、Panasonic V-Log、ARRI LogC、DJI D-Log、Apple Log，名字不同思路一样
  • 曲线形状——线性把光原样记下；Log 把暗部抬起来、高光压下去，中间调拉平，同样的数值装进了更大的亮度范围
  • Log 是数据不是画面——它记录的是「光有多少」，不是「看起来什么样」
线性、Gamma 与 Log 的亮度响应曲线

配套看：动态范围 · 色深 · 色彩空间

操作步骤STEPS

  1. 拿到 Log 素材，先做转换再调色——CST 节点或技术 LUT 把 Log 转回 Rec.709
  2. 转换放最前的节点，创作调整放后面
  3. 没有现成 LUT 就用色彩空间转换（CST），输入选你的 Log 家族
  4. 转换完再动曝光和白平衡，顺序反了颜色会脏

练习PRACTICE

动手任务

找一条 Log 素材（教材工程里有灰片），先用 CST 转到 709 再微调；和直接对着灰片硬拉对比，看差别。

自检清单

做完任务后逐条自查，全部能打勾才算过。

常见问题FAQ

直接对着 Log 灰片调色不行吗？

不行。灰片的数值分布不是给人眼准备的，硬拉对比等于靠猜。先用 CST 或技术 LUT 翻译成 709，再谈调色。

手机也能拍 Log？

能，近年不少手机支持 Log 录制（比如 Apple Log）。同一个道理：灰是在存信息，用之前先转换。

Learning Objectives学习目标

After this card you can say why Log footage looks flat, what it is storing for you, and the first thing to do with a Log clip.

Concepts概念说明

Log is a packing method: it squeezes a dynamic range too big for the container into limited bit depth, at the cost of a flat, low-contrast image.

  • Flat is a feature, not a bug — highlight and shadow detail is all still there, just not shown to you yet
  • The families — Sony S-Log3, Canon C-Log, Panasonic V-Log, ARRI LogC, DJI D-Log, Apple Log: different names, same idea
  • The curve — linear records light as-is; Log lifts the shadows, compresses the highlights and flattens the midtones, packing a bigger brightness range into the same numbers
  • Log is data, not a picture — it records "how much light", not "how it should look"
Response curves of linear, gamma and Log

See also: Dynamic range · Bit depth · Colour space

Steps操作步骤

  1. Got Log footage? Transform first, grade second — a CST node or technical LUT brings Log back to Rec.709
  2. Transform goes in the earliest node, creative moves come after
  3. No matching LUT? Use a Color Space Transform (CST) and pick your Log family as input
  4. Only then touch exposure and white balance — wrong order, dirty colours

Practice练习

Hands-on task

Take a Log clip (the companion project has flat footage), transform it to 709 with a CST, then fine-tune. Compare with dragging the flat image around directly.

Self-check

Work through the task, then tick every line; all checked means you own this card.

FAQ常见问题

Why not just grade the flat Log image directly?

The values in a flat clip are not arranged for your eyes. Pushing contrast around is guesswork. Translate to 709 with a CST or technical LUT first, then grade.

Can phones shoot Log too?

Yes — many recent phones record Log (Apple Log, for one). Same principle: flat means stored information, transform before use.

本卡术语Terms in this card

色彩空间Color Space 对比度Contrast 曲线Curves Gamma（中间调）Gamma Lift（暗部）Lift 白平衡White Balance 调色Grade LUT（查找表）LUT 静帧Still 节点Node 变换Transform 位深Bit Depth 容器（封装）Container 动态范围Dynamic Range 色域Gamut