白点：什么算「白」White Point: What Counts as White
学习目标LEARNING OBJECTIVES
学完你能说清「白点」是什么——什么算「白」是被规定的——以及白点不匹配时整部片子怎么偏。
概念说明CONCEPTS
现实里的白没有标准答案：中午的阳光、阴天、灯泡、霓虹——都是白。数字影像必须挑一个参考白点，用 CIE 色度坐标钉死，不靠感觉。换标准=换白点=整部片子一起偏色。
D 系列日光标准，数字约等于色温：D50 → 5000K（印刷 / ICC）、D55 → 5500K、D65 → 6500K（sRGB、709、2020 的白点）。影院例外：DCI-P3 白点约 6300K，不等于 D65。
为什么标准写坐标而不是只写 K？色温一样、色调可以不同（偏绿或偏品）。
操作步骤STEPS
- 输入 / 时间线 / 输出——三处白点都对齐
- 跨标准（6300K 素材进 6500K 链路）要做转换
- 相机白平衡是拍摄时给传感器的参考，与后期白点是两回事
练习PRACTICE
动手任务
找一个「导出后颜色变了」的案例，按 白点 → gamma → 色域 的顺序排查一遍。
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
「导出后颜色变了」先查什么？
白点 → gamma → 色域，按这个顺序。
同一个 grade 两台设备不一样，是我调错了吗？
两台设备白点不同——你调的「白」在它那里就不是白。
相机白平衡不就是白点吗？
不是：白平衡是拍摄时给传感器的参考，后期白点是色彩管理按哪个标准解释数值。
Learning Objectives学习目标
After this card you can say what a white point is — that "what counts as white" is decided by convention — and how a mismatch shifts the whole film.
Concepts概念说明
There is no standard answer for white in reality: noon sun, an overcast sky, a bulb, neon — all white. Digital imaging must pick a reference white point, pinned down in CIE chromaticity coordinates, not by feel. Change the standard and you change the white point, and the whole film shifts.
D-series daylight illuminants, the number approximating colour temperature: D50 → 5000K (print / ICC), D55 → 5500K, D65 → 6500K (the white point of sRGB, 709 and 2020). Cinema exception: the DCI-P3 white point is about 6300K, not D65.
Why do standards write coordinates instead of just K? Same colour temperature, different tint possible (green or magenta shift).
Steps操作步骤
- Align white points at input, timeline and output
- Convert when crossing standards (6300K footage into a 6500K chain)
- Camera white balance is a shooting-time sensor reference, not the post white point
Practice练习
Hands-on task
Find a "colours changed after export" case and troubleshoot in the order white point → gamma → gamut.
Self-check
Work through the task, then tick every line; all checked means you own this card.
FAQ常见问题
Colours changed after export — what do I check first?
White point → gamma → gamut, in that order.
The same grade looks different on two devices — did I grade it wrong?
Two devices, two white points — the "white" you graded to isn't white there.
Isn't camera white balance the same thing?
No: white balance is a shooting-time reference for the sensor; the post white point is which standard interprets the numbers.
本卡术语Terms in this card
时间线Timeline 导出Export 色彩管理Color Management Gamma（中间调）Gamma 白平衡White Balance 调色Grade 色域Gamut PNGPNG 引用（剪辑）Reference 白点White Point