Answers.Body: <p>I would imagine it has something to do with the white point/primary chromaticities are Alexa Wide Gamut vs. Rec709.</p>
  
  <p><a href="http://www.arri.com/camera/alexa/learn/log_c_and_rec_709_video" rel="nofollow">http://www.arri.com/camera/alexa/learn/log_c_and_rec_709_video</a></p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-05-17T02:24:04.193Z
Answers.Text: Welcome to Video Production on Stack Exchange.  That made an interesting read.  Also enjoyed checking out your demo reel.
Answers.UserDisplayName: AJ Henderson
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-05-17T00:19:23.960Z
Answers.LastActivityDate: 2014-05-17T00:19:23.960Z
Answers.UserDisplayName: Greg Cotten
Body: <p>In the context of ASC-CDL, saturation is applied as:</p>
  
  <pre><code>luma = 0.2126*iR + 0.7152*iG + 0.0722*iB
  oR = luma + saturation*(iR-luma)
  oG = luma + saturation*(iG-luma)
  oB = luma + saturation*(iB-luma)
  </code></pre>
  
  <p>However, in the <a href="http://www.arri.com/?eID=registration&amp;file_uid=7760" rel="nofollow">ARRI Look Files in the ALEXA Camera</a> whitepaper they say:</p>
  
  <blockquote>
    <p>Note: The ALEXA saturation parameter differs from the ASC CDL
    saturation.</p>
  </blockquote>
  
  <p>But they don't specify in what way, and I can't find that information anywhere.</p>
  
  <p>Does anybody know?</p>
  
Tags: <color-correction>
Title: How does ARRI saturation formula differ from the ASC-CDL spec?
UserDisplayName: apalopohapa
ThreadText: # How does ARRI saturation formula differ from the ASC-CDL spec?
  
  (Asked by: username_0 on 2014-01-09)
  
  In the context of ASC-CDL, saturation is applied as:
  
  ```
  luma = 0.2126*iR + 0.7152*iG + 0.0722*iB
  oR = luma + saturation*(iR-luma)
  oG = luma + saturation*(iG-luma)
  oB = luma + saturation*(iB-luma)
  
  ```
  
  However, in the [ARRI Look Files in the ALEXA Camera](http://www.arri.com/?eID=registration&file_uid=7760) whitepaper they say:
  
  > Note: The ALEXA saturation parameter differs from the ASC CDL
  > saturation.
  
  But they don't specify in what way, and I can't find that information anywhere.
  
  Does anybody know?
  
  **Tags:** color-correction
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2014-05-17. Score: 2
  
  I would imagine it has something to do with the white point/primary chromaticities are Alexa Wide Gamut vs. Rec709.
  
  <http://www.arri.com/camera/alexa/learn/log_c_and_rec_709_video>
  
  > **Comments:**
  > **username_2**: Welcome to Video Production on Stack Exchange.  That made an interesting read.  Also enjoyed checking out your demo reel.  
  
  ---
  
  