Color Grading 顏色分級
本文檔主要是對Unity官方手冊的個人理解與總結（其實以翻譯記錄爲主：>）
僅作爲個人學習使用，不得作爲商業用途，歡迎轉載，並請註明出處。
文章中涉及到的操作都是基於Unity2018.4版本
參考鏈接：https://github.com/Unity-Technologies/PostProcessing/wiki/Color-Grading
Color grading is the process of altering or correcting the color and luminance of the final image. You can think of it like applying filters in software like Instagram.
顏色分級是改變或矯正最終圖像的顏色和亮度的過程。你可以把它想象成在Instagram這樣的軟件中應用了濾鏡。
The Color Grading effect comes with three modes:
顏色分級效果有三種模式:
- Low Dynamic Range: this mode is aimed at lower-end platforms but it can be used on any platform. Grading is applied to the final rendered frame clamped in a [0,1] range and stored in a standard LUT.
這種模式針對的是低端平臺，但可以在任何平臺上使用。分級應用於最終渲染幀，幀夾取在[0,1]範圍內，並存儲在標準色彩對照表(LUT)中。 - High Dynamic Range: this mode is aimed at platforms that support HDR rendering. All the color operations will be applied in HDR and stored into a 3D log-encoded LUT to ensure a sufficient range coverage and precision (Alexa LogC El1000).
此模式針對支持HDR渲染的平臺。所有的顏色操作都將應用於HDR中，並存儲到3D log-encoded的LUT中，以確保有足夠的覆蓋範圍和精度。 - External: this mode allows you to provide a custom 3D LUT authored in an external software.
此模式允許您提供自定義的3D LUT，通過外部軟件中編寫的方式。
Requirements
- Shader Model 3
See the Graphics Hardware Capabilities and Emulation page for further details and a list of compliant hardware.
Global Settings
Note: these are only available for the Low Definition Range and External modes.
注意：只有LDR和External模式有效
Properties
| Property | Function |
|---|---|
| Lookup Texture | LDR: A custom lookup texture (strip format, e.g. 256x16) to apply before the rest of the color grading operators. If none is provided, a neutral one will be generated internally. External: A custom 3D log-encoded texture. TODO: tutorial |
| 查找紋理 | LDR:自定義查找紋理(條狀格式，如256x16)，在其他顏色分級操作之前應用。如果沒有提供，則在內部生成一個非彩色的。External：一個自定義的3D log-encoded 紋理 |
| Contribution | LDR: How much of the lookup texture will contribute to the color grading. |
| 影響 | LDR:查找紋理會影響到顏色分級的程度 |
Note: volume blending between multiple LDR lookup textures is supported but only works correctly if they’re the same size. For this reason it is recommended to stick to a single LUT size for the whole project (256x16 or 1024x32).
注意:支持多個LDR查找紋理之間的體積混合，但只有當紋理的大小相同時才能正確工作。因此，建議在整個項目中堅持使用單一的LUT大小(256x16或1024x32)。
Tonemapping
Tonemapping is the process of remapping HDR values of an image into a range suitable to be displayed on screen. Tonemapping should always be applied when using an HDR camera, otherwise values color intensities above 1 will be clamped at 1, altering the scenes luminance balance.
色調映射是將圖像的HDR值重新映射到屏幕上適合的顯示範圍的過程。使用HDR相機時應始終使用色調映射，否則值大於1的顏色強度將被夾取到1，從而改變場景的亮度平衡。
The High Definition Range mode comes with 4 tonemapping operators:
HDR模式有4個色調映射操作：
-
None: no tonemapping will be applied. 無
-
Neutral: only does range-remapping with minimal impact on color hue & saturation and is generally a great starting point for extensive color grading.
非彩色：只重新映射對色彩色調和飽和度的影響最小範圍，通常是廣泛的色彩分級的一個很好的起點。 -
ACES: uses a close approximation of the reference ACES tonemapper for a more filmic look. Because of that, it is more contrasted than Neutral and has an effect on actual color hue & saturation. Note that if you enable this tonemapper all the grading operations will be done in the ACES color spaces for optimal precision and results.
使用一個接近參考ACES色調映射器的更接近電影的效果。正因爲如此，它比Neutral更有對比，並對實際色彩色調和飽和度有影響。請注意，如果您啓用此調色器，所有的分級操作都將在ACES顏色空間中進行，以獲得最佳的精度和結果。 -
Custom: a fully parametric tonemapper. 自定義
![在這裏插入圖片描述]()
Note: these are only available for the High Definition Range mode.
注意:這些只適用於HDR模式。
Properties
Note: Custom is the only tonemapper with settings. 注:只有自定義才需要調色器。
| Property | Function |
|---|---|
| Toe Strength | Affects the transition between the toe and the mid section of the curve. A value of 0 means no toe, a value of 1 means a very hard transition. |
| 腳趾強度 | 影響腳趾與曲線中段之間的過渡。值0表示沒有腳趾，值1表示過渡非常困難。 |
| Toe Length | Affects how much of the dynamic range is in the toe. With a small value, the toe will be very short and quickly transition into the linear section, and with a longer value having a longer toe. |
| 腳趾長度 | 影響腳趾的動態範圍。數值越小，腳趾越短，越快過渡到線段，數值越大，腳趾越長。 |
| Shoulder Strength | Affects the transition between the mid section and the shoulder of the curve. A value of 0 means no shoulder, value of 1 means a very hard transition. |
| 肩部強度 | 影響曲線中部和肩部之間的過渡。值0表示沒有肩膀，值1表示過渡非常困難。 |
| Shoulder Length | Affects how many F-stops (EV) to add to the dynamic range of the curve. |
| 肩部長度 | 影響向曲線的動態範圍添加多少個光圈數 (EV)。 |
| Shoulder Angle | Affects how much overshot to add to the shoulder. |
| 肩部角度 | 影響要添加到肩部的超調量。 |
| Gamma | Applies a gamma function to the curve. |
| Gamma | 對曲線應用伽馬函數。 |
White Balance
| Property | Function |
|---|---|
| Temperature | Sets the white balance to a custom color temperature. |
| 溫度 | 將白平衡設置爲自定義色溫。 |
| Tint | Sets the white balance to compensate for a green or magenta tint. |
| 色彩 | 設置白平衡以補償綠色或品紅色。 |
Tone
（譯註：少顯示了一個屬性）
| Property | Function |
|---|---|
| Post-exposure | Adjusts the overall exposure of the scene in EV units. This is applied after HDR effect and right before tonemapping so it won’t affect previous effects in the chain.Note: Only available with the High Definition Range mode. |
| 後曝光 | 調整場景的整體曝光度。這是在HDR效果之後和調色之前應用的，所以它不會影響之前的效果。注:只適用於HDR模式。 |
| Color Filter | Tints the render by multiplying a color. |
| 顏色過濾 | 通過乘以顏色來給渲染器着色。 |
| Hue Shift | Shifts the hue of all colors. |
| 色調偏移 | 改變所有顏色的色調。 |
| Saturation | Pushes the intensity of all colors. |
| 飽和度 | 推動所有顏色的強度。 |
| Brightness | Makes the image brighter or darker. Note: Only available with the Low Definition Range mode. |
| 亮度 | 使圖像變亮或變暗。注意:只適用於LDR模式。 |
| Contrast | Expands or shrinks the overall range of tonal values. |
| 對比度 | 擴展或縮小色調值的總體範圍。 |
Channel Mixer 通道混合器
This is used to modify the influence of each input color channel on the overall mix of the output channel. For example, increasing the influence of the green channel on the overall mix of the red channel will adjust all areas of the image containing green (including neutral/monochrome) to become more reddish in hue.
這用於修改每個輸入顏色通道對輸出通道總體混合的影響。例如，增加綠色通道對紅色通道整體混合的影響，將調整包含綠色(包括neutral/單色)的圖像的所有區域，使其色調變得更紅。
Properties
| Property | Function |
|---|---|
| Channel | Selects the output channel to modify. |
| 通道 | 選擇要修改的輸出通道 |
| Red | Modifies the influence of the red channel within the overall mix. |
| 紅色 | 修改紅色通道對要修改的輸出通道整體混合的影響程度 |
| … | … |
Trackballs 軌跡球
The trackballs are used to perform three-way color grading. Adjusting the position of the point on the trackball will have the effect of shifting the hue of the image towards that color in the given tonal range. Different trackballs are used to affect different ranges within the image. Adjusting the slider under the trackball offsets the color lightness of that range.
軌跡球用於執行三種顏色分級。在給定的色調範圍內，調整軌跡球上的點的位置將產生將圖像的色調向該顏色偏移的效果。不同的軌跡球用於影響圖像中的不同範圍。調整軌跡球下方的滑塊會偏移該範圍內的顏色亮度。
Note: you can right-click a trackball to reset it to its default value. You can also change the trackballs sensitivity by going to Edit -> Preferences -> PostProcessing.
注意:您可以右鍵單擊軌跡球將其重置爲默認值。您還可以通過進入Edit -> Preferences -> PostProcessing來更改跟蹤球的靈敏度。
Properties
| Property | Function |
|---|---|
| Lift | Adjusts the dark tones (or shadows). |
| 起步 | 調整暗色調（或陰影） |
| Gamma | Adjusts the mid-tones. |
| 伽瑪 | 調整中部色調 |
| Gain | Adjusts the highlights. |
| 增益 | 調整高亮部分 |
Grading Curves
Grading curves are an advanced way to adjust specific ranges in hue, saturation or luminosity in your image. By adjusting the curves on the eight available graphs you can achieve the effects of specific hue replacement, desaturating certain luminosities and much more.
分級曲線是一種先進的方法來調整特定範圍的色調，飽和度或亮度在您的圖像。通過調整八個可用的圖形曲線，您可以實現特定色調替換、降低某些亮度和飽和度等效果。
YRGB Curves
These curves, also called Master, Red, Green and Blue affect the selected input channels intensity across the whole image. The X axis of the graph represents input intensity and the Y axis represents output intensity for the selected channel. This can be used to further adjust the appearance of basic attributes such as contrast and brightness.
這些曲線也稱爲主曲線、紅曲線、綠曲線和藍曲線，它們影響整個圖像中所選輸入通道的強度。圖形的X軸表示輸入強度，Y軸表示所選通道的輸出強度。這可以用來進一步調整外觀的基本屬性，如對比度和亮度。
Note: these curves are only available with the Low Definition Range mode.
注意:這些曲線只適用於LDR模式。
Hue vs Hue
Used to shift hues within specific ranges. This curve shifts the input hue (X axis) according to the output hue (Y axis). This can be used to fine tune hues of specific ranges or perform color replacement.
用於在特定範圍內變換色調。該曲線根據輸出色相(Y軸)來移動輸入色相(X軸)。這可以用來微調特定範圍的色調或執行顏色替換。
Hue vs Sat
Used to adjust saturation of hues within specific ranges. This curve adjusts saturation (Y axis) according to the input hue (X axis). This can be used to tone down particularly bright areas or create artistic effects such as monochromatic except a single dominant color.
用於在特定範圍內調整色調的飽和度。該曲線根據輸入色調(X軸)調整飽和度(Y軸)。這可以用來降低特別明亮的區域或創造藝術效果，如單色，除了一個單一的主導顏色。
Sat vs Sat
Used to adjust saturation of areas of certain saturation. This curve adjusts saturation (Y axis) according to the input saturation (X axis). This can be used to fine tune saturation adjustments made with settings from the Tone section.
用於調整某些飽和度區域的飽和度。該曲線根據輸入飽和度(X軸)調整飽和度(Y軸)。這可以從色調部分調整與設置來微調飽和度。
Lum vs Sat
Used to adjust saturation of areas of certain luminance. This curve adjusts saturation (Y axis) according to the input luminance (X axis). This can be used to desaturate areas of darkness to provide an interesting visual contrast.
用於調整某些亮度區域的飽和度。該曲線根據輸入亮度(X軸)調整飽和度(Y軸)。這可以用來降低黑暗區域的飽和度，提供一個有趣的視覺對比。
