user2416: 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 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?

user5951: 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

2416: <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>
 5951: <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>
