RAW ISN』T MAGIC. WITH THE RIGHT TOOLS LOG DOES IT TOO.
http://www.xdcam-user.com/2020/11/raw-isnt-magic-with-the-right-tools-log-does-it-too/
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Raw是一個很出色的工具，我經常用。高質量的Raw是我拍攝時的首選。但它不是魔法，僅僅是一種不同的錄製編碼類型。
Raw can be a brilliant tool, I use it a lot. High quality raw is my preferred way of shooting. But it isn’t magic, it’s just a different type of recording codec.
太多的時候，人們說Raw是「成像器的原始數據」並且強調Raw和常規的視頻錄製有很大的不同，這點我也一樣沒有做好。錄製Raw的時候，記錄下的是來自於成像器的、轉換為色彩圖像之前的視頻幀。一個Raw幀也是一個圖像，它是由亮度值構成的點陣圖，每個像素代表了單獨一種顏色的亮度值，而色彩圖像的每個像素位置需要有紅、綠、藍或Y、Cb和Cr三個數值來定義。
All too often – and I’m as guilty as anyone – people talk about raw as 「raw sensor data」 a term that implies that raw really is something very different to a normal recording. In reality it’s really not that different. When shooting raw all that happens is that the video frames from the sensor are recorded before they are converted to a colour image. A raw frame is still a picture, it’s just that it’s a bitmap image made up of brightness values, each pixel represented by a single brightness code value rather than a colour image where each location in the image is represented by 3 values one for each of Red, Green and Blue or Luma, Cb and Cr.
由於Raw幀仍不過是普通的點陣圖，因此攝像機諸如白平衡、ISO等全部設置實際上也都燒錄到記錄文件中。每個像素只有一個值，這個值與攝像機設置相關。後期製作中沒有辦法改變實際錄製的內容。大多數的CMOS成像器都是日光平衡的，因此除非在攝像機開始錄製前調整白平衡——索尼攝像機通常這麼做，否則Raw錄製的是日光平衡。
As that raw frame is still nothing more than a normal bitmap all the cameras settings such as white balance, ISO etc are in fact baked in to the recording. Each pixel only has one single value and that value will have been determined by the way the camera is setup. Nothing you do in post production can change what was actually recorded. Most CMOS sensors are daylight balanced, so unless the camera adjusts the white balance prior to recording – which is what Sony normally do – your raw recording will be daylight balanced.
現代攝像機在拍攝log或者Raw的時候也同時記錄了描述攝像機在拍攝時的設置的元數據。
Modern cameras when shooting log or raw also record metadata that describes how the camera was set when the image was captured.
因此錄製的Raw文件也有特定的白平衡和ISO。我知道很多人聽到這點會很失望，甚至乾脆就不相信，但這就是Raw點陣圖的真相，每個像素點只有一個代碼值，而這個值是由攝像機的設置確定的。
So the recorded raw file already has a particular white balance and ISO. I know lots of people will be disappointed to hear this or simply refuse to believe this but that’s the truth about a raw bitmap image with a single code value for each pixel and that value is determined by the camera settings.
在後期製作中可以進行調整，但是調整的範圍不是無限的，這和在攝像機裡做調整是不一樣的。並且如果調整很大的話可能會影響圖像質量。
This can be adjusted later in post production, but the adjustment range is not unlimited and it is not the same as making an adjustment in the camera. Plus there can be consequences to the image quality if you make large adjustments.
在後期製作時，Log也可以進行廣泛的調整。有幾十年的時間膠片電影採用10bit的Cineon log（S-Log3基於這個對數伽馬曲線）進行掃描的，後期製作時使用的也是10bit的log，直12bit以及16bit線性中間片（例如OpenEXR）的出現。因此這應該能說服你實際上能用進行非常好非常廣泛的調色。
Log can be also adjusted extensively in post too. For decades feature films shot on film were scanned using 10 bit Cineon log (which is the log gamma curve S-Log3 is based on) and 10 bit log used for post production until 12 bit and then 16 bit linear intermediates came along like OpenEXR. So this should tell you that actually log can be graded very well and very extensively.
但是還是有很多人會說你用log進行調色沒有Raw那麼好。他們通常會以照片進行舉例，用Raw照片和普通圖片進行調整，之間會有非常大的區別。但是我們需要認識到，這是高壓縮的8bit jpeg圖片和通常無壓縮的12或14bit Raw照片之間的典型不同，這是一個不公平的比較，你當然會想到14bit的文件會更好。
But then many people will tell you that you can’t grade log as well as raw. Often they will give photographers as an example where there is a huge difference between what you can do with a raw photo and a normal image. But we also have to remember this is typically comparing what you can do with a highly compressed 8 bit jpeg file and an often uncompressed 12 or 14 bit raw file. It’s not a fair comparison, of course you would expect the 14 bit file to be better.
另一個爭論點大多集中在使用log進行後期製作時很難調整白平衡，它看起來不正常或整個跑偏了。這些問題與log無關，而與使用的工具有關。
The other argument often given is that it’s very hard to change the white balance of log in post, it doesn’t look right or it falls apart. Often these issues are nothing to do with the log recording but more to do with the tools being used.
使用Raw進行剪輯或者調色時，通常會使用指定的Raw工具或者插件，這些工具和插件都是針對特定的Raw的特性進行開發設計的。結果就是當你處理這些Raw文件時，所有的操作都是針對特定的Raw性能進行的最佳的優化處理。因此，為了得到最佳的log圖像的畫質，你也需要使用針對所用的log類型設計的工具，這點是相同的。舉個例子，你可以看到使用索尼的Catalyst Browse，只需要簡單地拖動滑塊就能夠完美的糾正S-log素材的白平衡和曝光，與大多數的Raw一樣高效。
When you work with raw in your editing or grading software you will almost always be using a dedicated raw tool or raw plugin designed for the flavour of raw you are using. As a result everything you do to the file is optimised for the exact flavour of raw you are dealing with. It shouldn’t come as a surprise to find that to get the best from log you should be using tools specifically designed for the type of log you are using. In the example below you can see how Sony’s Catalyst Browse can perfectly correctly change the white balance and exposure of S-log material with simple sliders just as effectively as most raw formats.
左邊是白平衡錯誤（3200k）的S-Log3片段，右邊是校正後的圖像。只是通過色溫和曝光滑塊進行了調整。
On the left is the original S-Log3 clip with the wrong white balance (3200K) and on the left is the corrected image. The only corrections made are via the Temperature slider and exposure slider.
大多數的非編中能過對Log加載正常線性或冪函數（709是冪函數），這一般不會得到理想的效果，這些軟體對Log的控制很少。你需要採用合適的調色軟體比如達文西或Log專用控制項。更好的是顏色管理工作流程，例如ACES，可以將您特定類型的Log實時轉換為特殊的數字中間片，並對中間片進行調色校正。沒有轉碼，您只需告訴ACES拍攝了哪些鏡頭，後臺就有奇蹟發生。完成此操作後，您就可以用與Raw完全相同的方式更改Log素材的白平衡或ISO。幾乎沒有什麼區別。
Applying the normal linear or power law (709 is power law) corrections found in most edit software to Log won’t have the desired effect and basic edit software rarely has proper log controls. You need to use a proper grading package like Resolve and it’s dedicated log controls. Better still some form of colour managed workflow like ACES where your specific type of log is precisely converted on the fly to a special digital intermediate and the corrections are made to the intermediate file. There is no transcoding, you just tell ACES what the footage was was shot on and magic happens under the hood. Once you have done that you can change the white balance or ISO of log material in exactly the same way as raw. There is very, very little difference.
上例中的S-Log3片段，這次是在DaVinci Resolve中使用ACES。唯一的校正是通過「色溫」滑塊進行白平衡更改，以及「Log偏移」輪，在ACES中可提供精確的曝光調整。
The same S-Log3 clip as in the above example, this time in DaVinci Resolve using ACES. The only corrections being made are via the Temp slider for the white balance change and the Log-Offset wheel which in ACES provides a precise exposure adjustment.
When people say you can’t push log, more often than not it isn’t a matter of can’t, it’s a case of can – but you need to use the right tools.
這是在Catalyst Browse中僅使用WB和ISO滑塊之後，完全沒有正確的白平衡和稍微過度曝光的log鏡頭的樣子。我不相信raw會看起來有所不同。
This is what log shot with completely the wrong white balance and slightly over exposed looks like after using nothing but the WB and ISO sliders in Catalyst Browse. I don’t believe raw would have looked any different.
較少的壓縮或較大的位深是Log或Raw記錄之間最大的差異，而不是數據是Log還是Raw。別忘了Raw數據通常是使用Log記錄的，這使「您不能對Log進行調色」的說法有點愚蠢。
Less compression or a greater bit depth are where the biggest differences between a log or raw recording come from, not so much from whether the data is log or raw. Don’t forget raw is often recorded using log, which kind of makes the 「you can’t grade log」 argument a bit daft.
攝像機廠家和Raw錄機廠家非常高興地讓每個人都認為Raw是魔法，更糟糕的是，讓人們相信任何類型的Raw都必須比其他所有類型的記錄都要好。閱讀任何攝像機論壇，您會看到很多諸如「這是Raw的，它必須是更好的」或「我需要Raw，因為Log不那麼理想」的案例，他們根本不了解Raw是什麼以及實際中Raw的壓縮方式，真正重要的位深。
Camera manufactures and raw recorder manufacturers are perfectly happy to allow everyone to believe raw is magic and worse still, let people believe that ANY type of raw must be better than all other types of recordings. Read though any camera forum and you will see plenty of examples of 「it’s raw so it must be better」 or 「I need raw because log isn’t as good」 without any comprehension of what raw is and how in reality it’s the way the raw is compressed and the bit depth that really matters.
如果以ProRes Raw為例：對於4K 24/25fps文件，比特率約為900Mb/s。對於常規的ProRes HQ文件，比特率約為800Mb/s。因此，兩者之間的文件大小差異根本不大。
If we take ProRes Raw as an example: For a 4K 24/25fps file the bit rate is around 900Mb/s. For a conventional ProRes HQ file the bit rate is around 800Mb/s. So the file size difference between the two is not at all big.
但是，ProRes Raw文件只需要存儲大約ProResHQ壓縮文件1/3的數據點。結果就是，即使ProRes Raw文件通常具有較高的位深——這本身通常意味著更好的質量更好的記錄，它的壓縮比非常非常低，因此帶來的偽像更少。
But the ProRes Raw file only has to store around 1/3 as many data points as the component ProResHQ file. As a result, even though the ProRes Raw file often has a higher bit depth, which in itself usually means better a better quality recording, it is also much, much less compressed and as a result will have fewer artefacts.
Raw能夠會減少壓縮比並提高位深，從而可以帶來更高質量的記錄，因此與普通的ProRes或其他壓縮文件相比，可以帶來調色上的優勢。最好的一點是沒有明顯的文件大小損失。因此，您擁有相同數量的數據，但您的數據具有更高的質量。因此，鑑於您不需要更多的存儲空間，應該使用哪種？壓縮小位深高的文件還是壓縮大的文件？
It’s the reduced compression and deeper bit depth possible with raw that can lead to higher quality recordings and as a result may bring some grading advantages compared to a normal ProRes or other compressed file. The best bit is there is no significant file size penalty. So you have the same amount of data, but you data should be of higher quality. So given that you won’t need more storage, which should you use? The higher bit depth less compressed file or the more compressed file?
但是，並非所有Raw文件都是相同的。有些攝像機具有高度壓縮的10bit Raw數據，坦率地說，它不會比大多數其他10bit記錄格式更好，因為您必須執行所有複雜的數學運算，才能從10bit的文件還原出彩色圖像。大多數攝像機在內部至少具備12bit能力。我相信Raw至少需要12bit才值得擁有。
But, not all raw files are the same. Some cameras feature highly compressed 10 bit raw, which frankly won’t be any better than most other 10 bit recordings as you are having to do all the complex math to create a colour image starting with just 10 bit. Most cameras do this internally at at least 12 bit. I believe raw needs to be at least 12 bit to be worth having.
如果攝像機能錄製無壓縮的12bit RGB或12bit YUV的Log，則可能與任何Raw一樣好，也很靈活。但是文件將很大。並不是說Raw就是魔術，而是Raw的壓縮程度通常要低得多，並且位深也可能更大（與攝像機相關）。這就是Raw更好的原因。
If you could record uncompressed 12 bit RGB or 12 bit component log from these cameras that would likely be just as good and just as flexible as any raw recordings. But the files would be huge. It’s not that raw is magic, it’s just that raw is generally much less compressed and depending on the camera may also have a greater bit depth. That’s where the benefits come from.